/*
   Copyright (c) 2000, 2019, Oracle and/or its affiliates.
   Copyright (c) 2010, 2019, MariaDB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA
*/

/* drop and alter of tables */

#include "sql_priv.h"
#include "unireg.h"
#include "debug_sync.h"
#include "sql_table.h"
#include "sql_rename.h" // do_rename
#include "sql_parse.h"                        // test_if_data_home_dir
#include "sql_cache.h"                          // query_cache_*
#include "sql_base.h"   // open_table_uncached, lock_table_names
#include "lock.h"       // mysql_unlock_tables
#include "strfunc.h"    // find_type2, find_set
#include "sql_truncate.h"                       // regenerate_locked_table 
#include "sql_partition.h"                      // mem_alloc_error,
                                                // generate_partition_syntax,
                                                // partition_info
#include "sql_db.h"                             // load_db_opt_by_name
#include "sql_time.h"                  // make_truncated_value_warning
#include "records.h"             // init_read_record, end_read_record
#include "filesort.h"            // filesort_free_buffers
#include "sql_select.h"                // setup_order,
                                       // make_unireg_sortorder
#include "sql_handler.h"               // mysql_ha_rm_tables
#include "discover.h"                  // readfrm
#include "my_pthread.h"                // pthread_mutex_t
#include "log_event.h"                 // Query_log_event
#include <hash.h>
#include <myisam.h>
#include <my_dir.h>
#include "create_options.h"
#include "sp_head.h"
#include "sp.h"
#include "sql_trigger.h"
#include "sql_parse.h"
#include "sql_show.h"
#include "transaction.h"
#include "datadict.h"  // dd_frm_type()
#include "sql_audit.h"

#ifdef __WIN__
#include <io.h>
#endif

const char *primary_key_name="PRIMARY";

static bool check_if_keyname_exists(const char *name,KEY *start, KEY *end);
static char *make_unique_key_name(const char *field_name,KEY *start,KEY *end);
static int copy_data_between_tables(THD *thd, TABLE *,TABLE *,
                                    List<Create_field> &, bool,
				    uint, ORDER *, ha_rows *,ha_rows *,
                                    enum enum_enable_or_disable, bool);

static bool prepare_blob_field(THD *thd, Create_field *sql_field);
static bool check_engine(THD *, const char *, const char *, HA_CREATE_INFO *);
static int mysql_prepare_create_table(THD *, HA_CREATE_INFO *, Alter_info *,
                                      bool, uint *, handler *, KEY **, uint *,
                                      int);
static uint blob_length_by_type(enum_field_types type);

/**
  @brief Helper function for explain_filename
  @param thd          Thread handle
  @param to_p         Explained name in system_charset_info
  @param end_p        End of the to_p buffer
  @param name         Name to be converted
  @param name_len     Length of the name, in bytes
*/
static char* add_identifier(THD* thd, char *to_p, const char * end_p,
                            const char* name, uint name_len)
{
  uint res;
  uint errors;
  const char *conv_name;
  char tmp_name[FN_REFLEN];
  char conv_string[FN_REFLEN];
  int quote;

  DBUG_ENTER("add_identifier");
  if (!name[name_len])
    conv_name= name;
  else
  {
    strnmov(tmp_name, name, name_len);
    tmp_name[name_len]= 0;
    conv_name= tmp_name;
  }
  res= strconvert(&my_charset_filename, conv_name, system_charset_info,
                  conv_string, FN_REFLEN, &errors);
  if (!res || errors)
  {
    DBUG_PRINT("error", ("strconvert of '%s' failed with %u (errors: %u)", conv_name, res, errors));
    conv_name= name;
  }
  else
  {
    DBUG_PRINT("info", ("conv '%s' -> '%s'", conv_name, conv_string));
    conv_name= conv_string;
  }

  quote = thd ? get_quote_char_for_identifier(thd, conv_name, res - 1) : '"';

  if (quote != EOF && (end_p - to_p > 2))
  {
    *(to_p++)= (char) quote;
    while (*conv_name && (end_p - to_p - 1) > 0)
    {
      uint length= my_mbcharlen(system_charset_info, *conv_name);
      if (!length)
        length= 1;
      if (length == 1 && *conv_name == (char) quote)
      { 
        if ((end_p - to_p) < 3)
          break;
        *(to_p++)= (char) quote;
        *(to_p++)= *(conv_name++);
      }
      else if (((long) length) < (end_p - to_p))
      {
        to_p= strnmov(to_p, conv_name, length);
        conv_name+= length;
      }
      else
        break;                               /* string already filled */
    }
    if (end_p > to_p) {
      *(to_p++)= (char) quote;
      if (end_p > to_p)
	*to_p= 0; /* terminate by NUL, but do not include it in the count */
    }
  }
  else
    to_p= strnmov(to_p, conv_name, end_p - to_p);
  DBUG_RETURN(to_p);
}


/**
  @brief Explain a path name by split it to database, table etc.
  
  @details Break down the path name to its logic parts
  (database, table, partition, subpartition).
  filename_to_tablename cannot be used on partitions, due to the #P# part.
  There can be up to 6 '#', #P# for partition, #SP# for subpartition
  and #TMP# or #REN# for temporary or renamed partitions.
  This should be used when something should be presented to a user in a
  diagnostic, error etc. when it would be useful to know what a particular
  file [and directory] means. Such as SHOW ENGINE STATUS, error messages etc.

  Examples:

    t1#P#p1                 table t1 partition p1
    t1#P#p1#SP#sp1          table t1 partition p1 subpartition sp1
    t1#P#p1#SP#sp1#TMP#     table t1 partition p1 subpartition sp1 temporary
    t1#P#p1#SP#sp1#REN#     table t1 partition p1 subpartition sp1 renamed

   @param      thd          Thread handle
   @param      from         Path name in my_charset_filename
                            Null terminated in my_charset_filename, normalized
                            to use '/' as directory separation character.
   @param      to           Explained name in system_charset_info
   @param      to_length    Size of to buffer
   @param      explain_mode Requested output format.
                            EXPLAIN_ALL_VERBOSE ->
                            [Database `db`, ]Table `tbl`[,[ Temporary| Renamed]
                            Partition `p` [, Subpartition `sp`]]
                            EXPLAIN_PARTITIONS_VERBOSE -> `db`.`tbl`
                            [[ Temporary| Renamed] Partition `p`
                            [, Subpartition `sp`]]
                            EXPLAIN_PARTITIONS_AS_COMMENT -> `db`.`tbl` |*
                            [,[ Temporary| Renamed] Partition `p`
                            [, Subpartition `sp`]] *|
                            (| is really a /, and it is all in one line)

   @retval     Length of returned string
*/

uint explain_filename(THD* thd,
		      const char *from,
                      char *to,
                      uint to_length,
                      enum_explain_filename_mode explain_mode)
{
  char *to_p= to;
  char *end_p= to_p + to_length;
  const char *db_name= NULL;
  int  db_name_len= 0;
  const char *table_name;
  int  table_name_len= 0;
  const char *part_name= NULL;
  int  part_name_len= 0;
  const char *subpart_name= NULL;
  int  subpart_name_len= 0;
  uint part_type= NORMAL_PART_NAME;

  const char *tmp_p;
  DBUG_ENTER("explain_filename");
  DBUG_PRINT("enter", ("from '%s'", from));
  tmp_p= from;
  table_name= from;
  /*
    If '/' then take last directory part as database.
    '/' is the directory separator, not FN_LIB_CHAR
  */
  while ((tmp_p= strchr(tmp_p, '/')))
  {
    db_name= table_name;
    /* calculate the length */
    db_name_len= tmp_p - db_name;
    tmp_p++;
    table_name= tmp_p;
  }
  tmp_p= table_name;
  /* Look if there are partition tokens in the table name. */
  while ((tmp_p= strchr(tmp_p, '#')))
  {
    tmp_p++;
    switch (tmp_p[0]) {
    case 'P':
    case 'p':
      if (tmp_p[1] == '#')
      {
        part_name= tmp_p + 2;
        tmp_p+= 2;
      }
      break;
    case 'S':
    case 's':
      if ((tmp_p[1] == 'P' || tmp_p[1] == 'p') && tmp_p[2] == '#')
      {
        part_name_len= tmp_p - part_name - 1;
        subpart_name= tmp_p + 3;
	tmp_p+= 3;
      }
      break;
    case 'T':
    case 't':
      if ((tmp_p[1] == 'M' || tmp_p[1] == 'm') &&
          (tmp_p[2] == 'P' || tmp_p[2] == 'p') &&
          tmp_p[3] == '#' && !tmp_p[4])
      {
        part_type= TEMP_PART_NAME;
        tmp_p+= 4;
      }
      break;
    case 'R':
    case 'r':
      if ((tmp_p[1] == 'E' || tmp_p[1] == 'e') &&
          (tmp_p[2] == 'N' || tmp_p[2] == 'n') &&
          tmp_p[3] == '#' && !tmp_p[4])
      {
        part_type= RENAMED_PART_NAME;
        tmp_p+= 4;
      }
      break;
    default:
      /* Not partition name part. */
      ;
    }
  }
  if (part_name)
  {
    table_name_len= part_name - table_name - 3;
    if (subpart_name)
      subpart_name_len= strlen(subpart_name);
    else
      part_name_len= strlen(part_name);
    if (part_type != NORMAL_PART_NAME)
    {
      if (subpart_name)
        subpart_name_len-= 5;
      else
        part_name_len-= 5;
    }
  }
  else
    table_name_len= strlen(table_name);
  if (db_name)
  {
    if (explain_mode == EXPLAIN_ALL_VERBOSE)
    {
      to_p= strnmov(to_p, ER_THD_OR_DEFAULT(thd, ER_DATABASE_NAME),
                                            end_p - to_p);
      *(to_p++)= ' ';
      to_p= add_identifier(thd, to_p, end_p, db_name, db_name_len);
      to_p= strnmov(to_p, ", ", end_p - to_p);
    }
    else
    {
      to_p= add_identifier(thd, to_p, end_p, db_name, db_name_len);
      to_p= strnmov(to_p, ".", end_p - to_p);
    }
  }
  if (explain_mode == EXPLAIN_ALL_VERBOSE)
  {
    to_p= strnmov(to_p, ER_THD_OR_DEFAULT(thd, ER_TABLE_NAME), end_p - to_p);
    *(to_p++)= ' ';
    to_p= add_identifier(thd, to_p, end_p, table_name, table_name_len);
  }
  else
    to_p= add_identifier(thd, to_p, end_p, table_name, table_name_len);
  if (part_name)
  {
    if (explain_mode == EXPLAIN_PARTITIONS_AS_COMMENT)
      to_p= strnmov(to_p, " /* ", end_p - to_p);
    else if (explain_mode == EXPLAIN_PARTITIONS_VERBOSE)
      to_p= strnmov(to_p, " ", end_p - to_p);
    else
      to_p= strnmov(to_p, ", ", end_p - to_p);
    if (part_type != NORMAL_PART_NAME)
    {
      if (part_type == TEMP_PART_NAME)
        to_p= strnmov(to_p, ER_THD_OR_DEFAULT(thd, ER_TEMPORARY_NAME),
                      end_p - to_p);
      else
        to_p= strnmov(to_p, ER_THD_OR_DEFAULT(thd, ER_RENAMED_NAME),
                      end_p - to_p);
      to_p= strnmov(to_p, " ", end_p - to_p);
    }
    to_p= strnmov(to_p, ER_THD_OR_DEFAULT(thd, ER_PARTITION_NAME),
                  end_p - to_p);
    *(to_p++)= ' ';
    to_p= add_identifier(thd, to_p, end_p, part_name, part_name_len);
    if (subpart_name)
    {
      to_p= strnmov(to_p, ", ", end_p - to_p);
      to_p= strnmov(to_p, ER_THD_OR_DEFAULT(thd, ER_SUBPARTITION_NAME),
                    end_p - to_p);
      *(to_p++)= ' ';
      to_p= add_identifier(thd, to_p, end_p, subpart_name, subpart_name_len);
    }
    if (explain_mode == EXPLAIN_PARTITIONS_AS_COMMENT)
      to_p= strnmov(to_p, " */", end_p - to_p);
  }
  DBUG_PRINT("exit", ("to '%s'", to));
  DBUG_RETURN(to_p - to);
}


/*
  Translate a file name to a table name (WL #1324).

  SYNOPSIS
    filename_to_tablename()
      from                      The file name in my_charset_filename.
      to                OUT     The table name in system_charset_info.
      to_length                 The size of the table name buffer.

  RETURN
    Table name length.
*/

uint filename_to_tablename(const char *from, char *to, uint to_length
#ifndef DBUG_OFF
                           , bool stay_quiet
#endif /* DBUG_OFF */
                           )
{
  uint errors;
  size_t res;
  DBUG_ENTER("filename_to_tablename");
  DBUG_PRINT("enter", ("from '%s'", from));

  if (!strncmp(from, tmp_file_prefix, tmp_file_prefix_length))
  {
    /* Temporary table name. */
    res= (strnmov(to, from, to_length) - to);
  }
  else
  {
    res= strconvert(&my_charset_filename, from,
                    system_charset_info,  to, to_length, &errors);
    if (errors) // Old 5.0 name
    {
      res= (strxnmov(to, to_length, MYSQL50_TABLE_NAME_PREFIX,  from, NullS) -
            to);
#ifndef DBUG_OFF
      if (!stay_quiet) {
#endif /* DBUG_OFF */
        sql_print_error("Invalid (old?) table or database name '%s'", from);
#ifndef DBUG_OFF
      }
#endif /* DBUG_OFF */
      /*
        TODO: add a stored procedure for fix table and database names,
        and mention its name in error log.
      */
    }
  }

  DBUG_PRINT("exit", ("to '%s'", to));
  DBUG_RETURN(res);
}


/**
  Check if given string begins with "#mysql50#" prefix
  
  @param   name          string to check cut 
  
  @retval
    FALSE  no prefix found
  @retval
    TRUE   prefix found
*/

bool check_mysql50_prefix(const char *name)
{
  return (name[0] == '#' && 
         !strncmp(name, MYSQL50_TABLE_NAME_PREFIX,
                  MYSQL50_TABLE_NAME_PREFIX_LENGTH));
}


/**
  Check if given string begins with "#mysql50#" prefix, cut it if so.
  
  @param   from          string to check and cut 
  @param   to[out]       buffer for result string
  @param   to_length     its size
  
  @retval
    0      no prefix found
  @retval
    non-0  result string length
*/

uint check_n_cut_mysql50_prefix(const char *from, char *to, uint to_length)
{
  if (check_mysql50_prefix(from))
    return (uint) (strmake(to, from + MYSQL50_TABLE_NAME_PREFIX_LENGTH,
                           to_length - 1) - to);
  return 0;
}


/*
  Translate a table name to a file name (WL #1324).

  SYNOPSIS
    tablename_to_filename()
      from                      The table name in system_charset_info.
      to                OUT     The file name in my_charset_filename.
      to_length                 The size of the file name buffer.

  RETURN
    File name length.
*/

uint tablename_to_filename(const char *from, char *to, uint to_length)
{
  uint errors, length;
  DBUG_ENTER("tablename_to_filename");
  DBUG_PRINT("enter", ("from '%s'", from));

  if ((length= check_n_cut_mysql50_prefix(from, to, to_length)))
  {
    /*
      Check if the name supplied is a valid mysql 5.0 name and 
      make the name a zero length string if it's not.
      Note that just returning zero length is not enough : 
      a lot of places don't check the return value and expect 
      a zero terminated string.
    */  
    if (check_table_name(to, length, TRUE))
    {
      to[0]= 0;
      length= 0;
    }
    DBUG_RETURN(length);
  }
  length= strconvert(system_charset_info, from,
                     &my_charset_filename, to, to_length, &errors);
  if (check_if_legal_tablename(to) &&
      length + 4 < to_length)
  {
    memcpy(to + length, "@@@", 4);
    length+= 3;
  }
  DBUG_PRINT("exit", ("to '%s'", to));
  DBUG_RETURN(length);
}


/*
  Creates path to a file: mysql_data_dir/db/table.ext

  SYNOPSIS
   build_table_filename()
     buff                       Where to write result in my_charset_filename.
                                This may be the same as table_name.
     bufflen                    buff size
     db                         Database name in system_charset_info.
     table_name                 Table name in system_charset_info.
     ext                        File extension.
     flags                      FN_FROM_IS_TMP or FN_TO_IS_TMP or FN_IS_TMP
                                table_name is temporary, do not change.

  NOTES

    Uses database and table name, and extension to create
    a file name in mysql_data_dir. Database and table
    names are converted from system_charset_info into "fscs".
    Unless flags indicate a temporary table name.
    'db' is always converted.
    'ext' is not converted.

    The conversion suppression is required for ALTER TABLE. This
    statement creates intermediate tables. These are regular
    (non-temporary) tables with a temporary name. Their path names must
    be derivable from the table name. So we cannot use
    build_tmptable_filename() for them.

  RETURN
    path length
*/

uint build_table_filename(char *buff, size_t bufflen, const char *db,
                          const char *table_name, const char *ext, uint flags)
{
  char dbbuff[FN_REFLEN];
  char tbbuff[FN_REFLEN];
  DBUG_ENTER("build_table_filename");
  DBUG_PRINT("enter", ("db: '%s'  table_name: '%s'  ext: '%s'  flags: %x",
                       db, table_name, ext, flags));

  if (flags & FN_IS_TMP) // FN_FROM_IS_TMP | FN_TO_IS_TMP
    strnmov(tbbuff, table_name, sizeof(tbbuff));
  else
    (void) tablename_to_filename(table_name, tbbuff, sizeof(tbbuff));

  (void) tablename_to_filename(db, dbbuff, sizeof(dbbuff));

  char *end = buff + bufflen;
  /* Don't add FN_ROOTDIR if mysql_data_home already includes it */
  char *pos = strnmov(buff, mysql_data_home, bufflen);
  size_t rootdir_len= strlen(FN_ROOTDIR);
  if (pos - rootdir_len >= buff &&
      memcmp(pos - rootdir_len, FN_ROOTDIR, rootdir_len) != 0)
    pos= strnmov(pos, FN_ROOTDIR, end - pos);
  pos= strxnmov(pos, end - pos, dbbuff, FN_ROOTDIR, NullS);
#ifdef USE_SYMDIR
  unpack_dirname(buff, buff);
  pos= strend(buff);
#endif
  pos= strxnmov(pos, end - pos, tbbuff, ext, NullS);

  DBUG_PRINT("exit", ("buff: '%s'", buff));
  DBUG_RETURN(pos - buff);
}


/*
  Creates path to a file: mysql_tmpdir/#sql1234_12_1.ext

  SYNOPSIS
   build_tmptable_filename()
     thd                        The thread handle.
     buff                       Where to write result in my_charset_filename.
     bufflen                    buff size

  NOTES

    Uses current_pid, thread_id, and tmp_table counter to create
    a file name in mysql_tmpdir.

  RETURN
    path length
*/

uint build_tmptable_filename(THD* thd, char *buff, size_t bufflen)
{
  DBUG_ENTER("build_tmptable_filename");

  char *p= strnmov(buff, mysql_tmpdir, bufflen);
  my_snprintf(p, bufflen - (p - buff), "/%s%lx_%lx_%x%s",
              tmp_file_prefix, current_pid,
              thd->thread_id, thd->tmp_table++, reg_ext);

  if (lower_case_table_names)
  {
    /* Convert all except tmpdir to lower case */
    my_casedn_str(files_charset_info, p);
  }

  size_t length= unpack_filename(buff, buff);
  DBUG_PRINT("exit", ("buff: '%s'", buff));
  DBUG_RETURN(length);
}

/*
--------------------------------------------------------------------------

   MODULE: DDL log
   -----------------

   This module is used to ensure that we can recover from crashes that occur
   in the middle of a meta-data operation in MySQL. E.g. DROP TABLE t1, t2;
   We need to ensure that both t1 and t2 are dropped and not only t1 and
   also that each table drop is entirely done and not "half-baked".

   To support this we create log entries for each meta-data statement in the
   ddl log while we are executing. These entries are dropped when the
   operation is completed.

   At recovery those entries that were not completed will be executed.

   There is only one ddl log in the system and it is protected by a mutex
   and there is a global struct that contains information about its current
   state.

   History:
   First version written in 2006 by Mikael Ronstrom
--------------------------------------------------------------------------
*/


struct st_global_ddl_log
{
  char file_name_str[FN_REFLEN];
  char *file_name;
  DDL_LOG_MEMORY_ENTRY *first_free;
  DDL_LOG_MEMORY_ENTRY *first_used;
  uint num_entries;
  File file_id;
  uint name_len;
  uint io_size;
  bool inited;
  bool do_release;
  bool recovery_phase;
  st_global_ddl_log() : inited(false), do_release(false) {}
};

st_global_ddl_log global_ddl_log;

mysql_mutex_t LOCK_gdl;

#define DDL_LOG_ENTRY_TYPE_POS 0
#define DDL_LOG_ACTION_TYPE_POS 1
#define DDL_LOG_PHASE_POS 2
#define DDL_LOG_NEXT_ENTRY_POS 4
#define DDL_LOG_NAME_POS 8

#define DDL_LOG_NUM_ENTRY_POS 0
#define DDL_LOG_NAME_LEN_POS 4
#define DDL_LOG_IO_SIZE_POS 8
#define DDL_LOG_HEADER_SIZE 12

/**
  Read one entry from ddl log file.
  @param[out]  file_entry_buf  Buffer to read into
  @param       entry_no        Entry number to read
  @param       size            Number of bytes of the entry to read

  @return Operation status
    @retval true   Error
    @retval false  Success
*/

static bool read_ddl_log_file_entry(uchar *file_entry_buf,
                                    uint entry_no,
                                    uint size)
{
  bool error= FALSE;
  File file_id= global_ddl_log.file_id;
  uint io_size= global_ddl_log.io_size;
  DBUG_ENTER("read_ddl_log_file_entry");
  DBUG_ASSERT(io_size >= size);

  if (mysql_file_pread(file_id, file_entry_buf, size, ((my_off_t)io_size) * entry_no,
                       MYF(MY_WME)) != size)
    error= TRUE;
  DBUG_RETURN(error);
}


/**
  Write one entry to ddl log file.

  @param  file_entry_buf  Buffer to write
  @param  entry_no        Entry number to write
  @param  size            Number of bytes of the entry to write

  @return Operation status
    @retval true   Error
    @retval false  Success
*/

static bool write_ddl_log_file_entry(uchar *file_entry_buf,
                                     uint entry_no,
                                     uint size)
{
  bool error= FALSE;
  File file_id= global_ddl_log.file_id;
  uint io_size= global_ddl_log.io_size;
  DBUG_ENTER("write_ddl_log_file_entry");
  DBUG_ASSERT(io_size >= size);

  if (mysql_file_pwrite(file_id, file_entry_buf, size,
                        io_size * entry_no, MYF(MY_WME)) != size)
    error= TRUE;
  DBUG_RETURN(error);
}


/*
  Write ddl log header
  SYNOPSIS
    write_ddl_log_header()
  RETURN VALUES
    TRUE                      Error
    FALSE                     Success
*/

static bool write_ddl_log_header()
{
  uint16 const_var;
  bool error= FALSE;
  uchar file_entry_buf[DDL_LOG_HEADER_SIZE];
  DBUG_ENTER("write_ddl_log_header");
  DBUG_ASSERT((DDL_LOG_NAME_POS + 3 * global_ddl_log.name_len)
                <= global_ddl_log.io_size);

  int4store(&file_entry_buf[DDL_LOG_NUM_ENTRY_POS],
            global_ddl_log.num_entries);
  const_var= global_ddl_log.name_len;
  int4store(&file_entry_buf[DDL_LOG_NAME_LEN_POS],
            (ulong) const_var);
  const_var= global_ddl_log.io_size;
  int4store(&file_entry_buf[DDL_LOG_IO_SIZE_POS],
            (ulong) const_var);
  if (write_ddl_log_file_entry(file_entry_buf, 0UL, DDL_LOG_HEADER_SIZE))
  {
    sql_print_error("Error writing ddl log header");
    DBUG_RETURN(TRUE);
  }
  (void) sync_ddl_log();
  DBUG_RETURN(error);
}


/*
  Create ddl log file name
  SYNOPSIS
    create_ddl_log_file_name()
    file_name                   Filename setup
  RETURN VALUES
    NONE
*/

static inline void create_ddl_log_file_name(char *file_name)
{
  strxmov(file_name, mysql_data_home, "/", "ddl_log.log", NullS);
}


/*
  Read header of ddl log file
  SYNOPSIS
    read_ddl_log_header()
  RETURN VALUES
    > 0                  Last entry in ddl log
    0                    No entries in ddl log
  DESCRIPTION
    When we read the ddl log header we get information about maximum sizes
    of names in the ddl log and we also get information about the number
    of entries in the ddl log.
*/

static uint read_ddl_log_header()
{
  char file_entry_buf[DDL_LOG_HEADER_SIZE];
  char file_name[FN_REFLEN];
  uint entry_no;
  bool successful_open= FALSE;
  DBUG_ENTER("read_ddl_log_header");
  DBUG_ASSERT(global_ddl_log.io_size <= IO_SIZE);

  create_ddl_log_file_name(file_name);
  if ((global_ddl_log.file_id= mysql_file_open(key_file_global_ddl_log,
                                               file_name,
                                               O_RDWR | O_BINARY, MYF(0))) >= 0)
  {
    if (read_ddl_log_file_entry((uchar *) file_entry_buf, 0UL,
                                DDL_LOG_HEADER_SIZE))
    {
      /* Write message into error log */
      sql_print_error("Failed to read ddl log file in recovery");
    }
    else
      successful_open= TRUE;
  }
  if (successful_open)
  {
    entry_no= uint4korr(&file_entry_buf[DDL_LOG_NUM_ENTRY_POS]);
    global_ddl_log.name_len= uint4korr(&file_entry_buf[DDL_LOG_NAME_LEN_POS]);
    global_ddl_log.io_size= uint4korr(&file_entry_buf[DDL_LOG_IO_SIZE_POS]);
  }
  else
  {
    entry_no= 0;
  }
  global_ddl_log.first_free= NULL;
  global_ddl_log.first_used= NULL;
  global_ddl_log.num_entries= 0;
  mysql_mutex_init(key_LOCK_gdl, &LOCK_gdl, MY_MUTEX_INIT_FAST);
  global_ddl_log.do_release= true;
  DBUG_RETURN(entry_no);
}


/**
  Set ddl log entry struct from buffer
  @param read_entry      Entry number
  @param file_entry_buf  Buffer to use
  @param ddl_log_entry   Entry to be set

  @note Pointers in ddl_log_entry will point into file_entry_buf!
*/

static void set_ddl_log_entry_from_buf(uint read_entry,
                                       uchar *file_entry_buf,
                                       DDL_LOG_ENTRY *ddl_log_entry)
{
  uint inx;
  uchar single_char;
  DBUG_ENTER("set_ddl_log_entry_from_buf");
  ddl_log_entry->entry_pos= read_entry;
  single_char= file_entry_buf[DDL_LOG_ENTRY_TYPE_POS];
  ddl_log_entry->entry_type= (enum ddl_log_entry_code)single_char;
  single_char= file_entry_buf[DDL_LOG_ACTION_TYPE_POS];
  ddl_log_entry->action_type= (enum ddl_log_action_code)single_char;
  ddl_log_entry->phase= file_entry_buf[DDL_LOG_PHASE_POS];
  ddl_log_entry->next_entry= uint4korr(&file_entry_buf[DDL_LOG_NEXT_ENTRY_POS]);
  ddl_log_entry->name= (char*) &file_entry_buf[DDL_LOG_NAME_POS];
  inx= DDL_LOG_NAME_POS + global_ddl_log.name_len;
  ddl_log_entry->from_name= (char*) &file_entry_buf[inx];
  inx+= global_ddl_log.name_len;
  ddl_log_entry->handler_name= (char*) &file_entry_buf[inx];
  DBUG_VOID_RETURN;
}
 

/*
  Initialise ddl log
  SYNOPSIS
    init_ddl_log()

  DESCRIPTION
    Write the header of the ddl log file and length of names. Also set
    number of entries to zero.

  RETURN VALUES
    TRUE                     Error
    FALSE                    Success
*/

static bool init_ddl_log()
{
  char file_name[FN_REFLEN];
  DBUG_ENTER("init_ddl_log");

  if (global_ddl_log.inited)
    goto end;

  global_ddl_log.io_size= IO_SIZE;
  global_ddl_log.name_len= FN_LEN;
  create_ddl_log_file_name(file_name);
  if ((global_ddl_log.file_id= mysql_file_create(key_file_global_ddl_log,
                                                 file_name, CREATE_MODE,
                                                 O_RDWR | O_TRUNC | O_BINARY,
                                                 MYF(MY_WME))) < 0)
  {
    /* Couldn't create ddl log file, this is serious error */
    sql_print_error("Failed to open ddl log file");
    DBUG_RETURN(TRUE);
  }
  global_ddl_log.inited= TRUE;
  if (write_ddl_log_header())
  {
    (void) mysql_file_close(global_ddl_log.file_id, MYF(MY_WME));
    global_ddl_log.inited= FALSE;
    DBUG_RETURN(TRUE);
  }

end:
  DBUG_RETURN(FALSE);
}


/*
  Execute one action in a ddl log entry
  SYNOPSIS
    execute_ddl_log_action()
    ddl_log_entry              Information in action entry to execute
  RETURN VALUES
    TRUE                       Error
    FALSE                      Success
*/

static int execute_ddl_log_action(THD *thd, DDL_LOG_ENTRY *ddl_log_entry)
{
  bool frm_action= FALSE;
  LEX_STRING handler_name;
  handler *file= NULL;
  MEM_ROOT mem_root;
  int error= TRUE;
  char to_path[FN_REFLEN];
  char from_path[FN_REFLEN];
#ifdef WITH_PARTITION_STORAGE_ENGINE
  char *par_ext= (char*)".par";
#endif
  handlerton *hton;
  DBUG_ENTER("execute_ddl_log_action");

  if (ddl_log_entry->entry_type == DDL_IGNORE_LOG_ENTRY_CODE)
  {
    DBUG_RETURN(FALSE);
  }
  DBUG_PRINT("ddl_log",
             ("execute type %c next %u name '%s' from_name '%s' handler '%s'",
             ddl_log_entry->action_type,
             ddl_log_entry->next_entry,
             ddl_log_entry->name,
             ddl_log_entry->from_name,
             ddl_log_entry->handler_name));
  handler_name.str= (char*)ddl_log_entry->handler_name;
  handler_name.length= strlen(ddl_log_entry->handler_name);
  init_sql_alloc(&mem_root, TABLE_ALLOC_BLOCK_SIZE, 0); 
  if (!strcmp(ddl_log_entry->handler_name, reg_ext))
    frm_action= TRUE;
  else
  {
    plugin_ref plugin= ha_resolve_by_name(thd, &handler_name);
    if (!plugin)
    {
      my_error(ER_ILLEGAL_HA, MYF(0), ddl_log_entry->handler_name);
      goto error;
    }
    hton= plugin_data(plugin, handlerton*);
    file= get_new_handler((TABLE_SHARE*)0, &mem_root, hton);
    if (!file)
    {
      mem_alloc_error(sizeof(handler));
      goto error;
    }
  }
  switch (ddl_log_entry->action_type)
  {
    case DDL_LOG_REPLACE_ACTION:
    case DDL_LOG_DELETE_ACTION:
    {
      if (ddl_log_entry->phase == 0)
      {
        if (frm_action)
        {
          strxmov(to_path, ddl_log_entry->name, reg_ext, NullS);
          if ((error= mysql_file_delete(key_file_frm, to_path, MYF(MY_WME))))
          {
            if (my_errno != ENOENT)
              break;
          }
#ifdef WITH_PARTITION_STORAGE_ENGINE
          strxmov(to_path, ddl_log_entry->name, par_ext, NullS);
          (void) mysql_file_delete(key_file_partition, to_path, MYF(MY_WME));
#endif
        }
        else
        {
          if ((error= file->ha_delete_table(ddl_log_entry->name)))
          {
            if (error != ENOENT && error != HA_ERR_NO_SUCH_TABLE)
              break;
          }
        }
        if ((deactivate_ddl_log_entry(ddl_log_entry->entry_pos)))
          break;
        (void) sync_ddl_log();
        error= FALSE;
        if (ddl_log_entry->action_type == DDL_LOG_DELETE_ACTION)
          break;
      }
      DBUG_ASSERT(ddl_log_entry->action_type == DDL_LOG_REPLACE_ACTION);
      /*
        Fall through and perform the rename action of the replace
        action. We have already indicated the success of the delete
        action in the log entry by stepping up the phase.
      */
    }
    case DDL_LOG_RENAME_ACTION:
    {
      error= TRUE;
      if (frm_action)
      {
        strxmov(to_path, ddl_log_entry->name, reg_ext, NullS);
        strxmov(from_path, ddl_log_entry->from_name, reg_ext, NullS);
        if (mysql_file_rename(key_file_frm, from_path, to_path, MYF(MY_WME)))
          break;
#ifdef WITH_PARTITION_STORAGE_ENGINE
        strxmov(to_path, ddl_log_entry->name, par_ext, NullS);
        strxmov(from_path, ddl_log_entry->from_name, par_ext, NullS);
        (void) mysql_file_rename(key_file_partition, from_path, to_path, MYF(MY_WME));
#endif
      }
      else
      {
        if (file->ha_rename_table(ddl_log_entry->from_name,
                                  ddl_log_entry->name))
          break;
      }
      if ((deactivate_ddl_log_entry(ddl_log_entry->entry_pos)))
        break;
      (void) sync_ddl_log();
      error= FALSE;
      break;
    }
    default:
      DBUG_ASSERT(0);
      break;
  }
  delete file;
error:
  free_root(&mem_root, MYF(0)); 
  DBUG_RETURN(error);
}


/*
  Get a free entry in the ddl log
  SYNOPSIS
    get_free_ddl_log_entry()
    out:active_entry                A ddl log memory entry returned
  RETURN VALUES
    TRUE                       Error
    FALSE                      Success
*/

static bool get_free_ddl_log_entry(DDL_LOG_MEMORY_ENTRY **active_entry,
                                   bool *write_header)
{
  DDL_LOG_MEMORY_ENTRY *used_entry;
  DDL_LOG_MEMORY_ENTRY *first_used= global_ddl_log.first_used;
  DBUG_ENTER("get_free_ddl_log_entry");

  mysql_mutex_assert_owner(&LOCK_gdl);
  if (global_ddl_log.first_free == NULL)
  {
    if (!(used_entry= (DDL_LOG_MEMORY_ENTRY*)my_malloc(
                              sizeof(DDL_LOG_MEMORY_ENTRY), MYF(MY_WME))))
    {
      sql_print_error("Failed to allocate memory for ddl log free list");
      DBUG_RETURN(TRUE);
    }
    global_ddl_log.num_entries++;
    used_entry->entry_pos= global_ddl_log.num_entries;
    *write_header= TRUE;
  }
  else
  {
    used_entry= global_ddl_log.first_free;
    global_ddl_log.first_free= used_entry->next_log_entry;
    *write_header= FALSE;
  }
  /*
    Move from free list to used list
  */
  used_entry->next_log_entry= first_used;
  used_entry->prev_log_entry= NULL;
  used_entry->next_active_log_entry= NULL;
  global_ddl_log.first_used= used_entry;
  if (first_used)
    first_used->prev_log_entry= used_entry;

  *active_entry= used_entry;
  DBUG_RETURN(FALSE);
}


/*
  External interface methods for the DDL log Module
  ---------------------------------------------------
*/

/*
  SYNOPSIS
    write_ddl_log_entry()
    ddl_log_entry         Information about log entry
    out:entry_written     Entry information written into   

  RETURN VALUES
    TRUE                      Error
    FALSE                     Success

  DESCRIPTION
    A careful write of the ddl log is performed to ensure that we can
    handle crashes occurring during CREATE and ALTER TABLE processing.
*/

bool write_ddl_log_entry(DDL_LOG_ENTRY *ddl_log_entry,
                         DDL_LOG_MEMORY_ENTRY **active_entry)
{
  bool error, write_header;
  char file_entry_buf[IO_SIZE];
  DBUG_ENTER("write_ddl_log_entry");

  if (init_ddl_log())
  {
    DBUG_RETURN(TRUE);
  }
  memset(file_entry_buf, 0, sizeof(file_entry_buf));
  file_entry_buf[DDL_LOG_ENTRY_TYPE_POS]=
                                    (char)DDL_LOG_ENTRY_CODE;
  file_entry_buf[DDL_LOG_ACTION_TYPE_POS]=
                                    (char)ddl_log_entry->action_type;
  file_entry_buf[DDL_LOG_PHASE_POS]= 0;
  int4store(&file_entry_buf[DDL_LOG_NEXT_ENTRY_POS],
            ddl_log_entry->next_entry);
  DBUG_ASSERT(strlen(ddl_log_entry->name) < global_ddl_log.name_len);
  strmake(&file_entry_buf[DDL_LOG_NAME_POS], ddl_log_entry->name,
          global_ddl_log.name_len - 1);
  if (ddl_log_entry->action_type == DDL_LOG_RENAME_ACTION ||
      ddl_log_entry->action_type == DDL_LOG_REPLACE_ACTION)
  {
    DBUG_ASSERT(strlen(ddl_log_entry->from_name) < global_ddl_log.name_len);
    strmake(&file_entry_buf[DDL_LOG_NAME_POS + global_ddl_log.name_len],
            ddl_log_entry->from_name, global_ddl_log.name_len - 1);
  }
  else
    file_entry_buf[DDL_LOG_NAME_POS + global_ddl_log.name_len]= 0;
  DBUG_ASSERT(strlen(ddl_log_entry->handler_name) < global_ddl_log.name_len);
  strmake(&file_entry_buf[DDL_LOG_NAME_POS + (2*global_ddl_log.name_len)],
          ddl_log_entry->handler_name, global_ddl_log.name_len - 1);
  if (get_free_ddl_log_entry(active_entry, &write_header))
  {
    DBUG_RETURN(TRUE);
  }
  error= FALSE;
  DBUG_PRINT("ddl_log",
             ("write type %c next %u name '%s' from_name '%s' handler '%s'",
             (char) file_entry_buf[DDL_LOG_ACTION_TYPE_POS],
             ddl_log_entry->next_entry,
             (char*) &file_entry_buf[DDL_LOG_NAME_POS],
             (char*) &file_entry_buf[DDL_LOG_NAME_POS +
                                     global_ddl_log.name_len],
             (char*) &file_entry_buf[DDL_LOG_NAME_POS +
                                     (2*global_ddl_log.name_len)]));
  if (write_ddl_log_file_entry((uchar*) file_entry_buf,
                               (*active_entry)->entry_pos, IO_SIZE))
  {
    error= TRUE;
    sql_print_error("Failed to write entry_no = %u",
                    (*active_entry)->entry_pos);
  }
  if (write_header && !error)
  {
    (void) sync_ddl_log();
    if (write_ddl_log_header())
      error= TRUE;
  }
  if (error)
    release_ddl_log_memory_entry(*active_entry);
  DBUG_RETURN(error);
}


/*
  Write final entry in the ddl log
  SYNOPSIS
    write_execute_ddl_log_entry()
    first_entry                    First entry in linked list of entries
                                   to execute, if 0 = NULL it means that
                                   the entry is removed and the entries
                                   are put into the free list.
    complete                       Flag indicating we are simply writing
                                   info about that entry has been completed
    in:out:active_entry            Entry to execute, 0 = NULL if the entry
                                   is written first time and needs to be
                                   returned. In this case the entry written
                                   is returned in this parameter
  RETURN VALUES
    TRUE                           Error
    FALSE                          Success

  DESCRIPTION
    This is the last write in the ddl log. The previous log entries have
    already been written but not yet synched to disk.
    We write a couple of log entries that describes action to perform.
    This entries are set-up in a linked list, however only when a first
    execute entry is put as the first entry these will be executed.
    This routine writes this first 
*/ 

bool write_execute_ddl_log_entry(uint first_entry,
                                 bool complete,
                                 DDL_LOG_MEMORY_ENTRY **active_entry)
{
  bool write_header= FALSE;
  char file_entry_buf[IO_SIZE];
  DBUG_ENTER("write_execute_ddl_log_entry");

  if (init_ddl_log())
  {
    DBUG_RETURN(TRUE);
  }
  memset(file_entry_buf, 0, sizeof(file_entry_buf));
  if (!complete)
  {
    /*
      We haven't synched the log entries yet, we synch them now before
      writing the execute entry. If complete is true we haven't written
      any log entries before, we are only here to write the execute
      entry to indicate it is done.
    */
    (void) sync_ddl_log();
    file_entry_buf[DDL_LOG_ENTRY_TYPE_POS]= (char)DDL_LOG_EXECUTE_CODE;
  }
  else
    file_entry_buf[DDL_LOG_ENTRY_TYPE_POS]= (char)DDL_IGNORE_LOG_ENTRY_CODE;
  int4store(&file_entry_buf[DDL_LOG_NEXT_ENTRY_POS], first_entry);
  if (!(*active_entry))
  {
    if (get_free_ddl_log_entry(active_entry, &write_header))
    {
      DBUG_RETURN(TRUE);
    }
  }
  if (write_ddl_log_file_entry((uchar*) file_entry_buf,
                               (*active_entry)->entry_pos,
                               IO_SIZE))
  {
    sql_print_error("Error writing execute entry in ddl log");
    release_ddl_log_memory_entry(*active_entry);
    DBUG_RETURN(TRUE);
  }
  (void) sync_ddl_log();
  if (write_header)
  {
    if (write_ddl_log_header())
    {
      release_ddl_log_memory_entry(*active_entry);
      DBUG_RETURN(TRUE);
    }
  }
  DBUG_RETURN(FALSE);
}


/*
  For complex rename operations we need to deactivate individual entries.
  SYNOPSIS
    deactivate_ddl_log_entry()
    entry_no                      Entry position of record to change
  RETURN VALUES
    TRUE                         Error
    FALSE                        Success
  DESCRIPTION
    During replace operations where we start with an existing table called
    t1 and a replacement table called t1#temp or something else and where
    we want to delete t1 and rename t1#temp to t1 this is not possible to
    do in a safe manner unless the ddl log is informed of the phases in
    the change.

    Delete actions are 1-phase actions that can be ignored immediately after
    being executed.
    Rename actions from x to y is also a 1-phase action since there is no
    interaction with any other handlers named x and y.
    Replace action where drop y and x -> y happens needs to be a two-phase
    action. Thus the first phase will drop y and the second phase will
    rename x -> y.
*/

bool deactivate_ddl_log_entry(uint entry_no)
{
  uchar file_entry_buf[DDL_LOG_NAME_POS];
  DBUG_ENTER("deactivate_ddl_log_entry");


  /*
    Only need to read and write the first bytes of the entry, where
    ENTRY_TYPE, ACTION_TYPE and PHASE reside. Using DDL_LOG_NAME_POS
    to include all info except for the names.
  */
  if (!read_ddl_log_file_entry(file_entry_buf, entry_no, DDL_LOG_NAME_POS))
  {
    if (file_entry_buf[DDL_LOG_ENTRY_TYPE_POS] == DDL_LOG_ENTRY_CODE)
    {
      if (file_entry_buf[DDL_LOG_ACTION_TYPE_POS] == DDL_LOG_DELETE_ACTION ||
          file_entry_buf[DDL_LOG_ACTION_TYPE_POS] == DDL_LOG_RENAME_ACTION ||
          (file_entry_buf[DDL_LOG_ACTION_TYPE_POS] == DDL_LOG_REPLACE_ACTION &&
           file_entry_buf[DDL_LOG_PHASE_POS] == 1))
        file_entry_buf[DDL_LOG_ENTRY_TYPE_POS]= DDL_IGNORE_LOG_ENTRY_CODE;
      else if (file_entry_buf[DDL_LOG_ACTION_TYPE_POS] == DDL_LOG_REPLACE_ACTION)
      {
        DBUG_ASSERT(file_entry_buf[DDL_LOG_PHASE_POS] == 0);
        file_entry_buf[DDL_LOG_PHASE_POS]= 1;
      }
      else
      {
        DBUG_ASSERT(0);
      }
      if (write_ddl_log_file_entry(file_entry_buf, entry_no, DDL_LOG_NAME_POS))
      {
        sql_print_error("Error in deactivating log entry. Position = %u",
                        entry_no);
        DBUG_RETURN(TRUE);
      }
    }
  }
  else
  {
    sql_print_error("Failed in reading entry before deactivating it");
    DBUG_RETURN(TRUE);
  }
  DBUG_RETURN(FALSE);
}


/*
  Sync ddl log file
  SYNOPSIS
    sync_ddl_log()
  RETURN VALUES
    TRUE                      Error
    FALSE                     Success
*/

bool sync_ddl_log()
{
  bool error= FALSE;
  DBUG_ENTER("sync_ddl_log");

  if ((!global_ddl_log.recovery_phase) &&
      init_ddl_log())
  {
    DBUG_RETURN(TRUE);
  }
  if (mysql_file_sync(global_ddl_log.file_id, MYF(0)))
  {
    /* Write to error log */
    sql_print_error("Failed to sync ddl log");
    error= TRUE;
  }
  DBUG_RETURN(error);
}


/*
  Release a log memory entry
  SYNOPSIS
    release_ddl_log_memory_entry()
    log_memory_entry                Log memory entry to release
  RETURN VALUES
    NONE
*/

void release_ddl_log_memory_entry(DDL_LOG_MEMORY_ENTRY *log_entry)
{
  DDL_LOG_MEMORY_ENTRY *first_free= global_ddl_log.first_free;
  DDL_LOG_MEMORY_ENTRY *next_log_entry= log_entry->next_log_entry;
  DDL_LOG_MEMORY_ENTRY *prev_log_entry= log_entry->prev_log_entry;
  DBUG_ENTER("release_ddl_log_memory_entry");
  mysql_mutex_assert_owner(&LOCK_gdl);

  global_ddl_log.first_free= log_entry;
  log_entry->next_log_entry= first_free;

  if (prev_log_entry)
    prev_log_entry->next_log_entry= next_log_entry;
  else
    global_ddl_log.first_used= next_log_entry;
  if (next_log_entry)
    next_log_entry->prev_log_entry= prev_log_entry;
  DBUG_VOID_RETURN;
}


/*
  Execute one entry in the ddl log. Executing an entry means executing
  a linked list of actions.
  SYNOPSIS
    execute_ddl_log_entry()
    first_entry                Reference to first action in entry
  RETURN VALUES
    TRUE                       Error
    FALSE                      Success
*/

bool execute_ddl_log_entry(THD *thd, uint first_entry)
{
  DDL_LOG_ENTRY ddl_log_entry;
  uint read_entry= first_entry;
  uchar file_entry_buf[IO_SIZE];
  DBUG_ENTER("execute_ddl_log_entry");

  mysql_mutex_lock(&LOCK_gdl);
  do
  {
    if (read_ddl_log_file_entry(file_entry_buf, read_entry, IO_SIZE))
    {
      /* Print the error to the log and continue with next log entry */
      sql_print_error("Failed to read entry = %u from ddl log",
                      read_entry);
      break;
    }
    set_ddl_log_entry_from_buf(read_entry, file_entry_buf, &ddl_log_entry);
    DBUG_ASSERT(ddl_log_entry.entry_type == DDL_LOG_ENTRY_CODE ||
                ddl_log_entry.entry_type == DDL_IGNORE_LOG_ENTRY_CODE);

    if (execute_ddl_log_action(thd, &ddl_log_entry))
    {
      /* Print the error to the log and continue with next log entry */
      sql_print_error("Failed to execute action for entry = %u from ddl log",
                      read_entry);
      break;
    }
    read_entry= ddl_log_entry.next_entry;
  } while (read_entry);
  mysql_mutex_unlock(&LOCK_gdl);
  DBUG_RETURN(FALSE);
}


/*
  Close the ddl log
  SYNOPSIS
    close_ddl_log()
  RETURN VALUES
    NONE
*/

static void close_ddl_log()
{
  DBUG_ENTER("close_ddl_log");
  if (global_ddl_log.file_id >= 0)
  {
    (void) mysql_file_close(global_ddl_log.file_id, MYF(MY_WME));
    global_ddl_log.file_id= (File) -1;
  }
  DBUG_VOID_RETURN;
}


/*
  Execute the ddl log at recovery of MySQL Server
  SYNOPSIS
    execute_ddl_log_recovery()
  RETURN VALUES
    NONE
*/

void execute_ddl_log_recovery()
{
  uint num_entries, i;
  THD *thd;
  DDL_LOG_ENTRY ddl_log_entry;
  uchar *file_entry_buf;
  uint io_size;
  char file_name[FN_REFLEN];
  DBUG_ENTER("execute_ddl_log_recovery");

  /*
    Initialise global_ddl_log struct
  */
  global_ddl_log.inited= FALSE;
  global_ddl_log.recovery_phase= TRUE;
  global_ddl_log.io_size= IO_SIZE;
  global_ddl_log.file_id= (File) -1;

  /*
    To be able to run this from boot, we allocate a temporary THD
  */
  if (!(thd=new THD))
    DBUG_VOID_RETURN;
  thd->thread_stack= (char*) &thd;
  thd->store_globals();

  num_entries= read_ddl_log_header();
  io_size= global_ddl_log.io_size;
  file_entry_buf= (uchar*) my_malloc(io_size, MYF(0));
  if (!file_entry_buf)
  {
    sql_print_error("Failed to allocate buffer for recover ddl log");
    DBUG_VOID_RETURN;
  }
  for (i= 1; i < num_entries + 1; i++)
  {
    if (read_ddl_log_file_entry(file_entry_buf, i, io_size))
    {
      sql_print_error("Failed to read entry no = %u from ddl log",
                       i);
      continue;
    }

    set_ddl_log_entry_from_buf(i, file_entry_buf, &ddl_log_entry);
    if (ddl_log_entry.entry_type == DDL_LOG_EXECUTE_CODE)
    {
      if (execute_ddl_log_entry(thd, ddl_log_entry.next_entry))
      {
        /* Real unpleasant scenario but we continue anyways.  */
        continue;
      }
    }
  }
  close_ddl_log();
  create_ddl_log_file_name(file_name);
  (void) mysql_file_delete(key_file_global_ddl_log, file_name, MYF(0));
  global_ddl_log.recovery_phase= FALSE;
  delete thd;
  my_free(file_entry_buf);
  /* Remember that we don't have a THD */
  my_pthread_setspecific_ptr(THR_THD,  0);
  DBUG_VOID_RETURN;
}


/*
  Release all memory allocated to the ddl log
  SYNOPSIS
    release_ddl_log()
  RETURN VALUES
    NONE
*/

void release_ddl_log()
{
  DDL_LOG_MEMORY_ENTRY *free_list;
  DDL_LOG_MEMORY_ENTRY *used_list;
  DBUG_ENTER("release_ddl_log");

  if (!global_ddl_log.do_release)
    DBUG_VOID_RETURN;

  mysql_mutex_lock(&LOCK_gdl);
  free_list= global_ddl_log.first_free;
  used_list= global_ddl_log.first_used;
  while (used_list)
  {
    DDL_LOG_MEMORY_ENTRY *tmp= used_list->next_log_entry;
    my_free(used_list);
    used_list= tmp;
  }
  while (free_list)
  {
    DDL_LOG_MEMORY_ENTRY *tmp= free_list->next_log_entry;
    my_free(free_list);
    free_list= tmp;
  }
  close_ddl_log();
  global_ddl_log.inited= 0;
  mysql_mutex_unlock(&LOCK_gdl);
  mysql_mutex_destroy(&LOCK_gdl);
  global_ddl_log.do_release= false;
  DBUG_VOID_RETURN;
}


/*
---------------------------------------------------------------------------

  END MODULE DDL log
  --------------------

---------------------------------------------------------------------------
*/


/**
   @brief construct a temporary shadow file name.

   @details Make a shadow file name used by ALTER TABLE to construct the
   modified table (with keeping the original). The modified table is then
   moved back as original table. The name must start with the temp file
   prefix so it gets filtered out by table files listing routines. 
    
   @param[out] buff      buffer to receive the constructed name
   @param      bufflen   size of buff
   @param      lpt       alter table data structure

   @retval     path length
*/

uint build_table_shadow_filename(char *buff, size_t bufflen, 
                                 ALTER_PARTITION_PARAM_TYPE *lpt)
{
  char tmp_name[FN_REFLEN];
  my_snprintf (tmp_name, sizeof (tmp_name), "%s-%s", tmp_file_prefix,
               lpt->table_name);
  return build_table_filename(buff, bufflen, lpt->db, tmp_name, "", FN_IS_TMP);
}


/*
  SYNOPSIS
    mysql_write_frm()
    lpt                    Struct carrying many parameters needed for this
                           method
    flags                  Flags as defined below
      WFRM_INITIAL_WRITE        If set we need to prepare table before
                                creating the frm file
      WFRM_INSTALL_SHADOW       If set we should install the new frm
      WFRM_KEEP_SHARE           If set we know that the share is to be
                                retained and thus we should ensure share
                                object is correct, if not set we don't
                                set the new partition syntax string since
                                we know the share object is destroyed.
      WFRM_PACK_FRM             If set we should pack the frm file and delete
                                the frm file

  RETURN VALUES
    TRUE                   Error
    FALSE                  Success

  DESCRIPTION
    A support method that creates a new frm file and in this process it
    regenerates the partition data. It works fine also for non-partitioned
    tables since it only handles partitioned data if it exists.
*/

bool mysql_write_frm(ALTER_PARTITION_PARAM_TYPE *lpt, uint flags)
{
  /*
    Prepare table to prepare for writing a new frm file where the
    partitions in add/drop state have temporarily changed their state
    We set tmp_table to avoid get errors on naming of primary key index.
  */
  int error= 0;
  char path[FN_REFLEN+1];
  char shadow_path[FN_REFLEN+1];
  char shadow_frm_name[FN_REFLEN+1];
  char frm_name[FN_REFLEN+1];
#ifdef WITH_PARTITION_STORAGE_ENGINE
  char *part_syntax_buf;
  uint syntax_len;
#endif
  DBUG_ENTER("mysql_write_frm");

  /*
    Build shadow frm file name
  */
  build_table_shadow_filename(shadow_path, sizeof(shadow_path) - 1, lpt);
  strxmov(shadow_frm_name, shadow_path, reg_ext, NullS);
  if (flags & WFRM_WRITE_SHADOW)
  {
    if (mysql_prepare_create_table(lpt->thd, lpt->create_info,
                                   lpt->alter_info,
                                   /*tmp_table*/ 1,
                                   &lpt->db_options,
                                   lpt->table->file,
                                   &lpt->key_info_buffer,
                                   &lpt->key_count,
                                   /*select_field_count*/ 0))
    {
      DBUG_RETURN(TRUE);
    }
#ifdef WITH_PARTITION_STORAGE_ENGINE
    {
      partition_info *part_info= lpt->table->part_info;
      if (part_info)
      {
        if (!(part_syntax_buf= generate_partition_syntax(part_info,
                                                         &syntax_len,
                                                         TRUE, TRUE,
                                                         lpt->create_info,
                                                         lpt->alter_info,
                                                         NULL)))
        {
          DBUG_RETURN(TRUE);
        }
        part_info->part_info_string= part_syntax_buf;
        part_info->part_info_len= syntax_len;
      }
    }
#endif
    /* Write shadow frm file */
    lpt->create_info->table_options= lpt->db_options;
    if ((mysql_create_frm(lpt->thd, shadow_frm_name, lpt->db,
                          lpt->table_name, lpt->create_info,
                          lpt->alter_info->create_list, lpt->key_count,
                          lpt->key_info_buffer, lpt->table->file)) ||
        lpt->table->file->ha_create_handler_files(shadow_path, NULL,
                                                  CHF_CREATE_FLAG,
                                                  lpt->create_info))
    {
      mysql_file_delete(key_file_frm, shadow_frm_name, MYF(0));
      error= 1;
      goto end;
    }
  }
  if (flags & WFRM_PACK_FRM)
  {
    /*
      We need to pack the frm file and after packing it we delete the
      frm file to ensure it doesn't get used. This is only used for
      handlers that have the main version of the frm file stored in the
      handler.
    */
    uchar *data;
    size_t length;
    if (readfrm(shadow_path, &data, &length) ||
        packfrm(data, length, &lpt->pack_frm_data, &lpt->pack_frm_len))
    {
      my_free(data);
      my_free(lpt->pack_frm_data);
      mem_alloc_error(length);
      error= 1;
      goto end;
    }
    error= mysql_file_delete(key_file_frm, shadow_frm_name, MYF(MY_WME));
  }
  if (flags & WFRM_INSTALL_SHADOW)
  {
#ifdef WITH_PARTITION_STORAGE_ENGINE
    partition_info *part_info= lpt->part_info;
#endif
    /*
      Build frm file name
    */
    build_table_filename(path, sizeof(path) - 1, lpt->db,
                         lpt->table_name, "", 0);
    strxmov(frm_name, path, reg_ext, NullS);
    /*
      When we are changing to use new frm file we need to ensure that we
      don't collide with another thread in process to open the frm file.
      We start by deleting the .frm file and possible .par file. Then we
      write to the DDL log that we have completed the delete phase by
      increasing the phase of the log entry. Next step is to rename the
      new .frm file and the new .par file to the real name. After
      completing this we write a new phase to the log entry that will
      deactivate it.
    */
    if (mysql_file_delete(key_file_frm, frm_name, MYF(MY_WME)) ||
#ifdef WITH_PARTITION_STORAGE_ENGINE
        lpt->table->file->ha_create_handler_files(path, shadow_path,
                                                  CHF_DELETE_FLAG, NULL) ||
        deactivate_ddl_log_entry(part_info->frm_log_entry->entry_pos) ||
        (sync_ddl_log(), FALSE) ||
        mysql_file_rename(key_file_frm,
                          shadow_frm_name, frm_name, MYF(MY_WME)) ||
        lpt->table->file->ha_create_handler_files(path, shadow_path,
                                                  CHF_RENAME_FLAG, NULL))
#else
        mysql_file_rename(key_file_frm,
                          shadow_frm_name, frm_name, MYF(MY_WME)))
#endif
    {
      error= 1;
      goto err;
    }
#ifdef WITH_PARTITION_STORAGE_ENGINE
    if (part_info && (flags & WFRM_KEEP_SHARE))
    {
      TABLE_SHARE *share= lpt->table->s;
      char *tmp_part_syntax_str;
      if (!(part_syntax_buf= generate_partition_syntax(part_info,
                                                       &syntax_len,
                                                       TRUE, TRUE,
                                                       lpt->create_info,
                                                       lpt->alter_info,
                                                       NULL)))
      {
        error= 1;
        goto err;
      }
      if (share->partition_info_buffer_size < syntax_len + 1)
      {
        share->partition_info_buffer_size= syntax_len+1;
        if (!(tmp_part_syntax_str= (char*) strmake_root(&share->mem_root,
                                                        part_syntax_buf,
                                                        syntax_len)))
        {
          error= 1;
          goto err;
        }
        share->partition_info_str= tmp_part_syntax_str;
      }
      else
        memcpy((char*) share->partition_info_str, part_syntax_buf,
               syntax_len + 1);
      share->partition_info_str_len= part_info->part_info_len= syntax_len;
      part_info->part_info_string= part_syntax_buf;
    }
#endif

err:
#ifdef WITH_PARTITION_STORAGE_ENGINE
    deactivate_ddl_log_entry(part_info->frm_log_entry->entry_pos);
    part_info->frm_log_entry= NULL;
    (void) sync_ddl_log();
#endif
    ;
  }

end:
  DBUG_RETURN(error);
}


/*
  SYNOPSIS
    write_bin_log()
    thd                           Thread object
    clear_error                   is clear_error to be called
    query                         Query to log
    query_length                  Length of query
    is_trans                      if the event changes either
                                  a trans or non-trans engine.

  RETURN VALUES
    NONE

  DESCRIPTION
    Write the binlog if open, routine used in multiple places in this
    file
*/

int write_bin_log(THD *thd, bool clear_error,
                  char const *query, ulong query_length, bool is_trans)
{
  int error= 0;
  if (mysql_bin_log.is_open())
  {
    int errcode= 0;
    thd_proc_info(thd, "Writing to binlog");
    if (clear_error)
      thd->clear_error();
    else
      errcode= query_error_code(thd, TRUE);
    error= thd->binlog_query(THD::STMT_QUERY_TYPE,
                             query, query_length, is_trans, FALSE, FALSE,
                             errcode);
    thd_proc_info(thd, 0);
  }
  return error;
}


/*
 delete (drop) tables.

  SYNOPSIS
   mysql_rm_table()
   thd			Thread handle
   tables		List of tables to delete
   if_exists		If 1, don't give error if one table doesn't exists

  NOTES
    Will delete all tables that can be deleted and give a compact error
    messages for tables that could not be deleted.
    If a table is in use, we will wait for all users to free the table
    before dropping it

    Wait if global_read_lock (FLUSH TABLES WITH READ LOCK) is set, but
    not if under LOCK TABLES.

  RETURN
    FALSE OK.  In this case ok packet is sent to user
    TRUE  Error

*/

bool mysql_rm_table(THD *thd,TABLE_LIST *tables, my_bool if_exists,
                    my_bool drop_temporary)
{
  bool error;
  Drop_table_error_handler err_handler;
  TABLE_LIST *table;

  DBUG_ENTER("mysql_rm_table");

  /* Disable drop of enabled log tables, must be done before name locking */
  for (table= tables; table; table= table->next_local)
  {
    if (check_if_log_table(table->db_length, table->db,
                           table->table_name_length, table->table_name, true))
    {
      my_error(ER_BAD_LOG_STATEMENT, MYF(0), "DROP");
      DBUG_RETURN(true);
    }
  }

  mysql_ha_rm_tables(thd, tables);

  if (!drop_temporary)
  {
    if (!thd->locked_tables_mode)
    {
      if (lock_table_names(thd, tables, NULL, thd->variables.lock_wait_timeout,
                           MYSQL_OPEN_SKIP_TEMPORARY))
        DBUG_RETURN(true);
      for (table= tables; table; table= table->next_local)
        tdc_remove_table(thd, TDC_RT_REMOVE_ALL, table->db, table->table_name,
                         false);
    }
    else
    {
      for (table= tables; table; table= table->next_local)
        if (table->open_type != OT_BASE_ONLY &&
	    find_temporary_table(thd, table))
        {
          /*
            A temporary table.

            Don't try to find a corresponding MDL lock or assign it
            to table->mdl_request.ticket. There can't be metadata
            locks for temporary tables: they are local to the session.

            Later in this function we release the MDL lock only if
            table->mdl_requeset.ticket is not NULL. Thus here we
            ensure that we won't release the metadata lock on the base
            table locked with LOCK TABLES as a side effect of temporary
            table drop.
          */
          DBUG_ASSERT(table->mdl_request.ticket == NULL);
        }
        else
        {
          /*
            Not a temporary table.

            Since 'tables' list can't contain duplicates (this is ensured
            by parser) it is safe to cache pointer to the TABLE instances
            in its elements.
          */
          table->table= find_table_for_mdl_upgrade(thd, table->db,
                                                   table->table_name, false);
          if (!table->table)
            DBUG_RETURN(true);
          table->mdl_request.ticket= table->table->mdl_ticket;
        }
    }
  }

  /* mark for close and remove all cached entries */
  thd->push_internal_handler(&err_handler);
  error= mysql_rm_table_no_locks(thd, tables, if_exists, drop_temporary,
                                 false, false);
  thd->pop_internal_handler();

  if (error)
    DBUG_RETURN(TRUE);
  my_ok(thd);
  DBUG_RETURN(FALSE);
}


/**
  Find the comment in the query.
  That's auxiliary function to be used handling DROP TABLE [comment].

  @param  thd             Thread handler
  @param  comment_pos     How many characters to skip before the comment.
                          Can be either 9 for DROP TABLE or
                          17 for DROP TABLE IF EXISTS
  @param  comment_start   returns the beginning of the comment if found.

  @retval  0  no comment found
  @retval  >0 the lenght of the comment found

*/
static uint32 comment_length(THD *thd, uint32 comment_pos,
                             const char **comment_start)
{
  /* We use uchar * here to make array indexing portable */
  const uchar *query= (uchar*) thd->query();
  const uchar *query_end= (uchar*) query + thd->query_length();
  const uchar *const state_map= thd->charset()->state_map;

  for (; query < query_end; query++)
  {
    if (state_map[static_cast<uchar>(*query)] == MY_LEX_SKIP)
      continue;
    if (comment_pos-- == 0)
      break;
  }
  if (query > query_end - 3 /* comment can't be shorter than 4 */ ||
      state_map[static_cast<uchar>(*query)] != MY_LEX_LONG_COMMENT || query[1] != '*')
    return 0;
  
  *comment_start= (char*) query;
  
  for (query+= 3; query < query_end; query++)
  {
    if (query[-1] == '*' && query[0] == '/')
      return (char*) query - *comment_start + 1;
  }
  return 0;
}


/**
  Execute the drop of a normal or temporary table.

  @param  thd             Thread handler
  @param  tables          Tables to drop
  @param  if_exists       If set, don't give an error if table doesn't exists.
                          In this case we give an warning of level 'NOTE'
  @param  drop_temporary  Only drop temporary tables
  @param  drop_view       Allow to delete VIEW .frm
  @param  dont_log_query  Don't write query to log files. This will also not
                          generate warnings if the handler files doesn't exists

  @retval  0  ok
  @retval  1  Error
  @retval -1  Thread was killed

  @note This function assumes that metadata locks have already been taken.
        It is also assumed that the tables have been removed from TDC.

  @todo When logging to the binary log, we should log
        tmp_tables and transactional tables as separate statements if we
        are in a transaction;  This is needed to get these tables into the
        cached binary log that is only written on COMMIT.
        The current code only writes DROP statements that only uses temporary
        tables to the cache binary log.  This should be ok on most cases, but
        not all.
*/

int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
                            bool drop_temporary, bool drop_view,
                            bool dont_log_query)
{
  TABLE_LIST *table;
  char path[FN_REFLEN + 1], *alias= NULL;
  uint path_length= 0;
  String wrong_tables;
  int error= 0;
  int non_temp_tables_count= 0;
  bool foreign_key_error=0;
  bool non_tmp_error= 0;
  bool trans_tmp_table_deleted= 0, non_trans_tmp_table_deleted= 0;
  bool non_tmp_table_deleted= 0;
  bool is_drop_tmp_if_exists_added= 0;
  String built_query;
  String built_trans_tmp_query, built_non_trans_tmp_query;
  DBUG_ENTER("mysql_rm_table_no_locks");

  /*
    Prepares the drop statements that will be written into the binary
    log as follows:

    1 - If we are not processing a "DROP TEMPORARY" it prepares a
    "DROP".

    2 - A "DROP" may result in a "DROP TEMPORARY" but the opposite is
    not true.

    3 - If the current format is row, the IF EXISTS token needs to be
    appended because one does not know if CREATE TEMPORARY was previously
    written to the binary log.

    4 - Add the IF_EXISTS token if necessary, i.e. if_exists is TRUE.

    5 - For temporary tables, there is a need to differentiate tables
    in transactional and non-transactional storage engines. For that,
    reason, two types of drop statements are prepared.

    The need to different the type of tables when dropping a temporary
    table stems from the fact that such drop does not commit an ongoing
    transaction and changes to non-transactional tables must be written
    ahead of the transaction in some circumstances.

    6- Slave SQL thread ignores all replicate-* filter rules
    for temporary tables with 'IF EXISTS' clause. (See sql/sql_parse.cc:
    mysql_execute_command() for details). These commands will be binlogged
    as they are, even if the default database (from USE `db`) is not present
    on the Slave. This can cause point in time recovery failures later
    when user uses the slave's binlog to re-apply. Hence at the time of binary
    logging, these commands will be written with fully qualified table names
    and use `db` will be suppressed.
  */
  if (!dont_log_query)
  {
    if (!drop_temporary)
    {
      const char *comment_start;
      uint32 comment_len;

      built_query.set_charset(thd->charset());
      if (if_exists)
        built_query.append("DROP TABLE IF EXISTS ");
      else
        built_query.append("DROP TABLE ");

      if ((comment_len= comment_length(thd, if_exists ? 17:9, &comment_start)))
      {
        built_query.append(comment_start, comment_len);
        built_query.append(" ");
      }
    }

    if (thd->is_current_stmt_binlog_format_row() || if_exists)
    {
      is_drop_tmp_if_exists_added= true;
      built_trans_tmp_query.set_charset(system_charset_info);
      built_trans_tmp_query.append("DROP TEMPORARY TABLE IF EXISTS ");
      built_non_trans_tmp_query.set_charset(system_charset_info);
      built_non_trans_tmp_query.append("DROP TEMPORARY TABLE IF EXISTS ");
    }
    else
    {
      built_trans_tmp_query.set_charset(system_charset_info);
      built_trans_tmp_query.append("DROP TEMPORARY TABLE ");
      built_non_trans_tmp_query.set_charset(system_charset_info);
      built_non_trans_tmp_query.append("DROP TEMPORARY TABLE ");
    }
  }

  for (table= tables; table; table= table->next_local)
  {
    bool is_trans;
    char *db=table->db;
    size_t db_length= table->db_length;
    handlerton *table_type;
    enum legacy_db_type frm_db_type= DB_TYPE_UNKNOWN;

    DBUG_PRINT("table", ("table_l: '%s'.'%s'  table: 0x%lx  s: 0x%lx",
                         table->db, table->table_name, (long) table->table,
                         table->table ? (long) table->table->s : (long) -1));

    /*
      If we are in locked tables mode and are dropping a temporary table,
      the ticket should be NULL to ensure that we don't release a lock
      on a base table later.
    */
    DBUG_ASSERT(!(thd->locked_tables_mode &&
                  table->open_type != OT_BASE_ONLY &&
                  find_temporary_table(thd, table) &&
                  table->mdl_request.ticket != NULL));

    /*
      drop_temporary_table may return one of the following error codes:
      .  0 - a temporary table was successfully dropped.
      .  1 - a temporary table was not found.
      . -1 - a temporary table is used by an outer statement.
    */
    if (table->open_type == OT_BASE_ONLY)
      error= 1;
    else if ((error= drop_temporary_table(thd, table, &is_trans)) == -1)
    {
      DBUG_ASSERT(thd->in_sub_stmt);
      goto err;
    }

    if ((drop_temporary && if_exists) || !error)
    {
      /*
        This handles the case of temporary tables. We have the following cases:

          . "DROP TEMPORARY" was executed and a temporary table was affected
          (i.e. drop_temporary && !error) or the if_exists was specified (i.e.
          drop_temporary && if_exists).

          . "DROP" was executed but a temporary table was affected (.i.e
          !error).
      */
      if (!dont_log_query)
      {
        /*
          If there is an error, we don't know the type of the engine
          at this point. So, we keep it in the trx-cache.
        */
        is_trans= error ? TRUE : is_trans;
        if (is_trans)
          trans_tmp_table_deleted= TRUE;
        else
          non_trans_tmp_table_deleted= TRUE;

        String *built_ptr_query=
          (is_trans ? &built_trans_tmp_query : &built_non_trans_tmp_query);
        /*
          Write the database name if it is not the current one or if
          thd->db is NULL or 'IF EXISTS' clause is present in 'DROP TEMPORARY'
          query.
        */
        if (thd->db == NULL || strcmp(db,thd->db) != 0
            || is_drop_tmp_if_exists_added )
        {
          append_identifier(thd, built_ptr_query, db, db_length);
          built_ptr_query->append(".");
        }
        append_identifier(thd, built_ptr_query, table->table_name,
                          table->table_name_length);
        built_ptr_query->append(",");
      }
      /*
        This means that a temporary table was droped and as such there
        is no need to proceed with the code that tries to drop a regular
        table.
      */
      if (!error) continue;
    }
    else if (!drop_temporary)
    {
      non_temp_tables_count++;

      if (thd->locked_tables_mode)
      {
        if (wait_while_table_is_used(thd, table->table, HA_EXTRA_NOT_USED,
                                     TDC_RT_REMOVE_NOT_OWN_AND_MARK_NOT_USABLE))
        {
          error= -1;
          goto err;
        }
        close_all_tables_for_name(thd, table->table->s,
                                  HA_EXTRA_PREPARE_FOR_DROP);
        table->table= 0;
      }

      /* Check that we have an exclusive lock on the table to be dropped. */
      DBUG_ASSERT(thd->mdl_context.is_lock_owner(MDL_key::TABLE, table->db,
                                                 table->table_name,
                                                 MDL_EXCLUSIVE));

      alias= (lower_case_table_names == 2) ? table->alias : table->table_name;
      /* remove .frm file and engine files */
      path_length= build_table_filename(path, sizeof(path) - 1, db, alias,
                                        reg_ext,
                                        table->internal_tmp_table ?
                                        FN_IS_TMP : 0);

      /*
        This handles the case where a "DROP" was executed and a regular
        table "may be" dropped as drop_temporary is FALSE and error is
        TRUE. If the error was FALSE a temporary table was dropped and
        regardless of the status of drop_tempoary a "DROP TEMPORARY"
        must be used.
      */
      if (!dont_log_query)
      {
        /*
          Note that unless if_exists is TRUE or a temporary table was deleted, 
          there is no means to know if the statement should be written to the
          binary log. See further information on this variable in what follows.
        */
        non_tmp_table_deleted= (if_exists ? TRUE : non_tmp_table_deleted);
        /*
          Don't write the database name if it is the current one (or if
          thd->db is NULL).
        */
        if (thd->db == NULL || strcmp(db,thd->db) != 0)
        {
          append_identifier(thd, &built_query, db, db_length);
          built_query.append(".");
        }

        append_identifier(thd, &built_query, table->table_name,
                          table->table_name_length);
        built_query.append(",");
      }
    }
    DEBUG_SYNC(thd, "rm_table_no_locks_before_delete_table");
    DBUG_EXECUTE_IF("sleep_before_no_locks_delete_table",
                    my_sleep(100000););
    error= 0;
    if (drop_temporary ||
        ((access(path, F_OK) &&
          ha_create_table_from_engine(thd, db, alias)) ||
         (!drop_view &&
          dd_frm_type(thd, path, &frm_db_type) != FRMTYPE_TABLE)))
    {
      /*
        One of the following cases happened:
          . "DROP TEMPORARY" but a temporary table was not found.
          . "DROP" but table was not found on disk and table can't be
            created from engine.
          . ./sql/datadict.cc +32 /Alfranio - TODO: We need to test this.
      */
      if (if_exists)
	push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
			    ER_BAD_TABLE_ERROR, ER(ER_BAD_TABLE_ERROR),
			    table->table_name);
      else
      {
        non_tmp_error = (drop_temporary ? non_tmp_error : TRUE);
        error= 1;
      }
    }
    else
    {
      char *end;
      /*
        Cannot use the db_type from the table, since that might have changed
        while waiting for the exclusive name lock.
      */
      if (frm_db_type == DB_TYPE_UNKNOWN)
      {
        dd_frm_type(thd, path, &frm_db_type);
        DBUG_PRINT("info", ("frm_db_type %d from %s", frm_db_type, path));
      }
      table_type= ha_resolve_by_legacy_type(thd, frm_db_type);
      // Remove extension for delete
      *(end= path + path_length - reg_ext_length)= '\0';
      DBUG_PRINT("info", ("deleting table of type %d",
                          (table_type ? table_type->db_type : 0)));
      error= ha_delete_table(thd, table_type, path, db, table->table_name,
                             !dont_log_query);

      /* No error if non existent table and 'IF EXIST' clause or view */
      if ((error == ENOENT || error == HA_ERR_NO_SUCH_TABLE) && 
	  (if_exists || table_type == NULL))
      {
	error= 0;
        thd->clear_error();
      }
      if (error == HA_ERR_ROW_IS_REFERENCED)
      {
	/* the table is referenced by a foreign key constraint */
	foreign_key_error= 1;
      }
      if (!error || error == ENOENT || error == HA_ERR_NO_SUCH_TABLE)
      {
        int new_error;
	/* Delete the table definition file */
	strmov(end,reg_ext);
        if (!(new_error= mysql_file_delete(key_file_frm, path, MYF(MY_WME))))
        {
          non_tmp_table_deleted= TRUE;
          new_error= Table_triggers_list::drop_all_triggers(thd, db,
                                                            table->table_name);
        }
        error|= new_error;
      }
       non_tmp_error= error ? TRUE : non_tmp_error;
    }
    if (error)
    {
      if (wrong_tables.length())
	wrong_tables.append(',');
      wrong_tables.append(String(table->table_name,system_charset_info));
    }
    else
    {
      mysql_audit_drop_table(thd, table);
    }
    DBUG_PRINT("table", ("table: 0x%lx  s: 0x%lx", (long) table->table,
                         table->table ? (long) table->table->s : (long) -1));

    DBUG_EXECUTE_IF("bug43138",
                    my_printf_error(ER_BAD_TABLE_ERROR,
                                    ER(ER_BAD_TABLE_ERROR), MYF(0),
                                    table->table_name););
  }
  DEBUG_SYNC(thd, "rm_table_no_locks_before_binlog");
  thd->thread_specific_used= TRUE;
  error= 0;
err:
  if (wrong_tables.length())
  {
    if (!foreign_key_error)
      my_printf_error(ER_BAD_TABLE_ERROR, ER(ER_BAD_TABLE_ERROR), MYF(0),
                      wrong_tables.c_ptr_safe());
    else
      my_message(ER_ROW_IS_REFERENCED, ER(ER_ROW_IS_REFERENCED), MYF(0));
    error= 1;
  }

  if (non_trans_tmp_table_deleted ||
      trans_tmp_table_deleted || non_tmp_table_deleted)
  {
    query_cache_invalidate3(thd, tables, 0);
    if (!dont_log_query && mysql_bin_log.is_open())
    {
      if (non_trans_tmp_table_deleted)
      {
          /* Chop of the last comma */
          built_non_trans_tmp_query.chop();
          built_non_trans_tmp_query.append(" /* generated by server */");
          error |= thd->binlog_query(THD::STMT_QUERY_TYPE,
                                     built_non_trans_tmp_query.ptr(),
                                     built_non_trans_tmp_query.length(),
                                     FALSE, FALSE,
                                     is_drop_tmp_if_exists_added,
                                     0);
      }
      if (trans_tmp_table_deleted)
      {
          /* Chop of the last comma */
          built_trans_tmp_query.chop();
          built_trans_tmp_query.append(" /* generated by server */");
          error |= thd->binlog_query(THD::STMT_QUERY_TYPE,
                                     built_trans_tmp_query.ptr(),
                                     built_trans_tmp_query.length(),
                                     TRUE, FALSE,
                                     is_drop_tmp_if_exists_added,
                                     0);
      }
      if (non_tmp_table_deleted)
      {
          /* Chop of the last comma */
          built_query.chop();
          built_query.append(" /* generated by server */");
          int error_code = (non_tmp_error ?
            (foreign_key_error ? ER_ROW_IS_REFERENCED : ER_BAD_TABLE_ERROR) : 0);
          error |= thd->binlog_query(THD::STMT_QUERY_TYPE,
                                     built_query.ptr(),
                                     built_query.length(),
                                     TRUE, FALSE, FALSE,
                                     error_code);
      }
    }
  }

  if (!drop_temporary)
  {
    /*
      Under LOCK TABLES we should release meta-data locks on the tables
      which were dropped.

      Leave LOCK TABLES mode if we managed to drop all tables which were
      locked. Additional check for 'non_temp_tables_count' is to avoid
      leaving LOCK TABLES mode if we have dropped only temporary tables.
    */
    if (thd->locked_tables_mode)
    {
      if (thd->lock && thd->lock->table_count == 0 && non_temp_tables_count > 0)
      {
        thd->locked_tables_list.unlock_locked_tables(thd);
        goto end;
      }
      for (table= tables; table; table= table->next_local)
      {
        /* Drop locks for all successfully dropped tables. */
        if (table->table == NULL && table->mdl_request.ticket)
        {
          /*
            Under LOCK TABLES we may have several instances of table open
            and locked and therefore have to remove several metadata lock
            requests associated with them.
          */
          thd->mdl_context.release_all_locks_for_name(table->mdl_request.ticket);
        }
      }
    }
    /*
      Rely on the caller to implicitly commit the transaction
      and release metadata locks.
    */
  }

end:
  DBUG_RETURN(error);
}


/*
  Quickly remove a table.

  SYNOPSIS
    quick_rm_table()
      base                      The handlerton handle.
      db                        The database name.
      table_name                The table name.
      flags                     flags for build_table_filename().

  RETURN
    0           OK
    != 0        Error
*/

bool quick_rm_table(handlerton *base,const char *db,
                    const char *table_name, uint flags)
{
  char path[FN_REFLEN + 1];
  bool error= 0;
  DBUG_ENTER("quick_rm_table");

  uint path_length= build_table_filename(path, sizeof(path) - 1,
                                         db, table_name, reg_ext, flags);
  if (mysql_file_delete(key_file_frm, path, MYF(0)))
    error= 1; /* purecov: inspected */
  path[path_length - reg_ext_length]= '\0'; // Remove reg_ext
  if (!(flags & FRM_ONLY))
    error|= ha_delete_table(current_thd, base, path, db, table_name, 0);
  DBUG_RETURN(error);
}

/*
  Sort keys in the following order:
  - PRIMARY KEY
  - UNIQUE keys where all column are NOT NULL
  - UNIQUE keys that don't contain partial segments
  - Other UNIQUE keys
  - Normal keys
  - Fulltext keys

  This will make checking for duplicated keys faster and ensure that
  PRIMARY keys are prioritized.
*/

static int sort_keys(KEY *a, KEY *b)
{
  ulong a_flags= a->flags, b_flags= b->flags;
  
  if (a_flags & HA_NOSAME)
  {
    if (!(b_flags & HA_NOSAME))
      return -1;
    if ((a_flags ^ b_flags) & HA_NULL_PART_KEY)
    {
      /* Sort NOT NULL keys before other keys */
      return (a_flags & HA_NULL_PART_KEY) ? 1 : -1;
    }
    if (a->name == primary_key_name)
      return -1;
    if (b->name == primary_key_name)
      return 1;
    /* Sort keys don't containing partial segments before others */
    if ((a_flags ^ b_flags) & HA_KEY_HAS_PART_KEY_SEG)
      return (a_flags & HA_KEY_HAS_PART_KEY_SEG) ? 1 : -1;
  }
  else if (b_flags & HA_NOSAME)
    return 1;					// Prefer b

  if ((a_flags ^ b_flags) & HA_FULLTEXT)
  {
    return (a_flags & HA_FULLTEXT) ? 1 : -1;
  }
  /*
    Prefer original key order.	usable_key_parts contains here
    the original key position.
  */
  return ((a->usable_key_parts < b->usable_key_parts) ? -1 :
	  (a->usable_key_parts > b->usable_key_parts) ? 1 :
	  0);
}

/*
  Check TYPELIB (set or enum) for duplicates

  SYNOPSIS
    check_duplicates_in_interval()
    set_or_name   "SET" or "ENUM" string for warning message
    name	  name of the checked column
    typelib	  list of values for the column
    dup_val_count  returns count of duplicate elements

  DESCRIPTION
    This function prints an warning for each value in list
    which has some duplicates on its right

  RETURN VALUES
    0             ok
    1             Error
*/

bool check_duplicates_in_interval(const char *set_or_name,
                                  const char *name, TYPELIB *typelib,
                                  CHARSET_INFO *cs, unsigned int *dup_val_count)
{
  TYPELIB tmp= *typelib;
  const char **cur_value= typelib->type_names;
  unsigned int *cur_length= typelib->type_lengths;
  *dup_val_count= 0;  
  
  for ( ; tmp.count > 1; cur_value++, cur_length++)
  {
    tmp.type_names++;
    tmp.type_lengths++;
    tmp.count--;
    if (find_type2(&tmp, (const char*)*cur_value, *cur_length, cs))
    {
      THD *thd= current_thd;
      ErrConvString err(*cur_value, *cur_length, cs);
      if ((current_thd->variables.sql_mode &
         (MODE_STRICT_TRANS_TABLES | MODE_STRICT_ALL_TABLES)))
      {
        my_error(ER_DUPLICATED_VALUE_IN_TYPE, MYF(0),
                 name, err.ptr(), set_or_name);
        return 1;
      }
      push_warning_printf(thd,MYSQL_ERROR::WARN_LEVEL_NOTE,
                          ER_DUPLICATED_VALUE_IN_TYPE,
                          ER(ER_DUPLICATED_VALUE_IN_TYPE),
                          name, err.ptr(), set_or_name);
      (*dup_val_count)++;
    }
  }
  return 0;
}


/*
  Check TYPELIB (set or enum) max and total lengths

  SYNOPSIS
    calculate_interval_lengths()
    cs            charset+collation pair of the interval
    typelib       list of values for the column
    max_length    length of the longest item
    tot_length    sum of the item lengths

  DESCRIPTION
    After this function call:
    - ENUM uses max_length
    - SET uses tot_length.

  RETURN VALUES
    void
*/
void calculate_interval_lengths(CHARSET_INFO *cs, TYPELIB *interval,
                                uint32 *max_length, uint32 *tot_length)
{
  const char **pos;
  uint *len;
  *max_length= *tot_length= 0;
  for (pos= interval->type_names, len= interval->type_lengths;
       *pos ; pos++, len++)
  {
    size_t length= cs->cset->numchars(cs, *pos, *pos + *len);
    *tot_length+= length;
    set_if_bigger(*max_length, (uint32)length);
  }
}


/*
  Prepare a create_table instance for packing

  SYNOPSIS
    prepare_create_field()
    sql_field     field to prepare for packing
    blob_columns  count for BLOBs
    timestamps    count for timestamps
    table_flags   table flags

  DESCRIPTION
    This function prepares a Create_field instance.
    Fields such as pack_flag are valid after this call.

  RETURN VALUES
   0	ok
   1	Error
*/

int prepare_create_field(Create_field *sql_field, 
			 uint *blob_columns, 
			 int *timestamps, int *timestamps_with_niladic,
			 longlong table_flags)
{
  unsigned int dup_val_count;
  DBUG_ENTER("prepare_field");

  /*
    This code came from mysql_prepare_create_table.
    Indent preserved to make patching easier
  */
  DBUG_ASSERT(sql_field->charset);

  switch (sql_field->sql_type) {
  case MYSQL_TYPE_BLOB:
  case MYSQL_TYPE_MEDIUM_BLOB:
  case MYSQL_TYPE_TINY_BLOB:
  case MYSQL_TYPE_LONG_BLOB:
    sql_field->pack_flag=FIELDFLAG_BLOB |
      pack_length_to_packflag(sql_field->pack_length -
                              portable_sizeof_char_ptr);
    if (sql_field->charset->state & MY_CS_BINSORT)
      sql_field->pack_flag|=FIELDFLAG_BINARY;
    sql_field->length=8;			// Unireg field length
    sql_field->unireg_check=Field::BLOB_FIELD;
    (*blob_columns)++;
    break;
  case MYSQL_TYPE_GEOMETRY:
#ifdef HAVE_SPATIAL
    if (!(table_flags & HA_CAN_GEOMETRY))
    {
      my_printf_error(ER_CHECK_NOT_IMPLEMENTED, ER(ER_CHECK_NOT_IMPLEMENTED),
                      MYF(0), "GEOMETRY");
      DBUG_RETURN(1);
    }
    sql_field->pack_flag=FIELDFLAG_GEOM |
      pack_length_to_packflag(sql_field->pack_length -
                              portable_sizeof_char_ptr);
    if (sql_field->charset->state & MY_CS_BINSORT)
      sql_field->pack_flag|=FIELDFLAG_BINARY;
    sql_field->length=8;			// Unireg field length
    sql_field->unireg_check=Field::BLOB_FIELD;
    (*blob_columns)++;
    break;
#else
    my_printf_error(ER_FEATURE_DISABLED,ER(ER_FEATURE_DISABLED), MYF(0),
                    sym_group_geom.name, sym_group_geom.needed_define);
    DBUG_RETURN(1);
#endif /*HAVE_SPATIAL*/
  case MYSQL_TYPE_VARCHAR:
#ifndef QQ_ALL_HANDLERS_SUPPORT_VARCHAR
    if (table_flags & HA_NO_VARCHAR)
    {
      /* convert VARCHAR to CHAR because handler is not yet up to date */
      sql_field->sql_type=    MYSQL_TYPE_VAR_STRING;
      sql_field->pack_length= calc_pack_length(sql_field->sql_type,
                                               (uint) sql_field->length);
      if ((sql_field->length / sql_field->charset->mbmaxlen) >
          MAX_FIELD_CHARLENGTH)
      {
        my_printf_error(ER_TOO_BIG_FIELDLENGTH, ER(ER_TOO_BIG_FIELDLENGTH),
                        MYF(0), sql_field->field_name,
                        static_cast<ulong>(MAX_FIELD_CHARLENGTH));
        DBUG_RETURN(1);
      }
    }
#endif
    /* fall through */
  case MYSQL_TYPE_STRING:
    sql_field->pack_flag=0;
    if (sql_field->charset->state & MY_CS_BINSORT)
      sql_field->pack_flag|=FIELDFLAG_BINARY;
    break;
  case MYSQL_TYPE_ENUM:
    sql_field->pack_flag=pack_length_to_packflag(sql_field->pack_length) |
      FIELDFLAG_INTERVAL;
    if (sql_field->charset->state & MY_CS_BINSORT)
      sql_field->pack_flag|=FIELDFLAG_BINARY;
    sql_field->unireg_check=Field::INTERVAL_FIELD;
    if (check_duplicates_in_interval("ENUM",sql_field->field_name,
                                     sql_field->interval,
                                     sql_field->charset, &dup_val_count))
      DBUG_RETURN(1);
    break;
  case MYSQL_TYPE_SET:
    sql_field->pack_flag=pack_length_to_packflag(sql_field->pack_length) |
      FIELDFLAG_BITFIELD;
    if (sql_field->charset->state & MY_CS_BINSORT)
      sql_field->pack_flag|=FIELDFLAG_BINARY;
    sql_field->unireg_check=Field::BIT_FIELD;
    if (check_duplicates_in_interval("SET",sql_field->field_name,
                                     sql_field->interval,
                                     sql_field->charset, &dup_val_count))
      DBUG_RETURN(1);
    /* Check that count of unique members is not more then 64 */
    if (sql_field->interval->count -  dup_val_count > sizeof(longlong)*8)
    {
       my_error(ER_TOO_BIG_SET, MYF(0), sql_field->field_name);
       DBUG_RETURN(1);
    }
    break;
  case MYSQL_TYPE_DATE:			// Rest of string types
  case MYSQL_TYPE_NEWDATE:
  case MYSQL_TYPE_TIME:
  case MYSQL_TYPE_DATETIME:
  case MYSQL_TYPE_NULL:
    sql_field->pack_flag=f_settype((uint) sql_field->sql_type);
    break;
  case MYSQL_TYPE_BIT:
    /* 
      We have sql_field->pack_flag already set here, see
      mysql_prepare_create_table().
    */
    break;
  case MYSQL_TYPE_NEWDECIMAL:
    sql_field->pack_flag=(FIELDFLAG_NUMBER |
                          (sql_field->flags & UNSIGNED_FLAG ? 0 :
                           FIELDFLAG_DECIMAL) |
                          (sql_field->flags & ZEROFILL_FLAG ?
                           FIELDFLAG_ZEROFILL : 0) |
                          (sql_field->decimals << FIELDFLAG_DEC_SHIFT));
    break;
  case MYSQL_TYPE_TIMESTAMP:
    /* We should replace old TIMESTAMP fields with their newer analogs */
    if (sql_field->unireg_check == Field::TIMESTAMP_OLD_FIELD)
    {
      if (!*timestamps)
      {
        sql_field->unireg_check= Field::TIMESTAMP_DNUN_FIELD;
        (*timestamps_with_niladic)++;
      }
      else
        sql_field->unireg_check= Field::NONE;
    }
    else if (sql_field->unireg_check != Field::NONE)
      (*timestamps_with_niladic)++;

    (*timestamps)++;
    /* fall-through */
  default:
    sql_field->pack_flag=(FIELDFLAG_NUMBER |
                          (sql_field->flags & UNSIGNED_FLAG ? 0 :
                           FIELDFLAG_DECIMAL) |
                          (sql_field->flags & ZEROFILL_FLAG ?
                           FIELDFLAG_ZEROFILL : 0) |
                          f_settype((uint) sql_field->sql_type) |
                          (sql_field->decimals << FIELDFLAG_DEC_SHIFT));
    break;
  }
  if (!(sql_field->flags & NOT_NULL_FLAG) ||
      (sql_field->vcol_info))  /* Make virtual columns allow NULL values */
    sql_field->pack_flag|= FIELDFLAG_MAYBE_NULL;
  if (sql_field->flags & NO_DEFAULT_VALUE_FLAG)
    sql_field->pack_flag|= FIELDFLAG_NO_DEFAULT;
  DBUG_RETURN(0);
}


/*
  Get character set from field object generated by parser using
  default values when not set.

  SYNOPSIS
    get_sql_field_charset()
    sql_field                 The sql_field object
    create_info               Info generated by parser

  RETURN VALUES
    cs                        Character set
*/

CHARSET_INFO* get_sql_field_charset(Create_field *sql_field,
                                    HA_CREATE_INFO *create_info)
{
  CHARSET_INFO *cs= sql_field->charset;

  if (!cs)
    cs= create_info->default_table_charset;
  /*
    table_charset is set only in ALTER TABLE t1 CONVERT TO CHARACTER SET csname
    if we want change character set for all varchar/char columns.
    But the table charset must not affect the BLOB fields, so don't
    allow to change my_charset_bin to somethig else.
  */
  if (create_info->table_charset && cs != &my_charset_bin)
    cs= create_info->table_charset;
  return cs;
}


bool check_duplicate_warning(THD *thd, char *msg, ulong length)
{
  List_iterator_fast<MYSQL_ERROR> it(thd->warning_info->warn_list());
  MYSQL_ERROR *err;
  while ((err= it++))
  {
    if (strncmp(msg, err->get_message_text(), length) == 0)
    {
      return true;
    }
  }
  return false;
}


/*
  Preparation for table creation

  SYNOPSIS
    mysql_prepare_create_table()
      thd                       Thread object.
      create_info               Create information (like MAX_ROWS).
      alter_info                List of columns and indexes to create
      tmp_table                 If a temporary table is to be created.
      db_options          INOUT Table options (like HA_OPTION_PACK_RECORD).
      file                      The handler for the new table.
      key_info_buffer     OUT   An array of KEY structs for the indexes.
      key_count           OUT   The number of elements in the array.
      select_field_count        The number of fields coming from a select table.

  DESCRIPTION
    Prepares the table and key structures for table creation.

  NOTES
    sets create_info->varchar if the table has a varchar

  RETURN VALUES
    FALSE    OK
    TRUE     error
*/

static int
mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
                           Alter_info *alter_info,
                           bool tmp_table,
                           uint *db_options,
                           handler *file, KEY **key_info_buffer,
                           uint *key_count, int select_field_count)
{
  const char	*key_name;
  Create_field	*sql_field,*dup_field;
  uint		field,null_fields,blob_columns,max_key_length;
  ulong		record_offset= 0;
  KEY		*key_info;
  KEY_PART_INFO *key_part_info;
  int		timestamps= 0, timestamps_with_niladic= 0;
  int		field_no,dup_no;
  int		select_field_pos,auto_increment=0;
  List_iterator<Create_field> it(alter_info->create_list);
  List_iterator<Create_field> it2(alter_info->create_list);
  uint total_uneven_bit_length= 0;
  DBUG_ENTER("mysql_prepare_create_table");

  LEX_STRING* connect_string = &create_info->connect_string;
  if (connect_string->length != 0 &&
      connect_string->length > CONNECT_STRING_MAXLEN &&
      (system_charset_info->cset->charpos(system_charset_info,
                                          connect_string->str,
                                          (connect_string->str +
                                           connect_string->length),
                                          CONNECT_STRING_MAXLEN)
      < connect_string->length))
  {
    my_error(ER_WRONG_STRING_LENGTH, MYF(0),
             connect_string->str, "CONNECTION", CONNECT_STRING_MAXLEN);
    DBUG_RETURN(TRUE);
  }

  select_field_pos= alter_info->create_list.elements - select_field_count;
  null_fields=blob_columns=0;
  create_info->varchar= 0;
  max_key_length= file->max_key_length();

  for (field_no=0; (sql_field=it++) ; field_no++)
  {
    CHARSET_INFO *save_cs;

    /*
      Initialize length from its original value (number of characters),
      which was set in the parser. This is necessary if we're
      executing a prepared statement for the second time.
    */
    sql_field->length= sql_field->char_length;
    save_cs= sql_field->charset= get_sql_field_charset(sql_field,
                                                       create_info);
    if ((sql_field->flags & BINCMP_FLAG) &&
	!(sql_field->charset= get_charset_by_csname(sql_field->charset->csname,
						    MY_CS_BINSORT,MYF(0))))
    {
      char tmp[65];
      strmake(strmake(tmp, save_cs->csname, sizeof(tmp)-4),
              STRING_WITH_LEN("_bin"));
      my_error(ER_UNKNOWN_COLLATION, MYF(0), tmp);
      DBUG_RETURN(TRUE);
    }

    /*
      Convert the default value from client character
      set into the column character set if necessary.
    */
    if (sql_field->def && 
        save_cs != sql_field->def->collation.collation &&
        (sql_field->sql_type == MYSQL_TYPE_VAR_STRING ||
         sql_field->sql_type == MYSQL_TYPE_STRING ||
         sql_field->sql_type == MYSQL_TYPE_SET ||
         sql_field->sql_type == MYSQL_TYPE_ENUM))
    {
      /*
        Starting from 5.1 we work here with a copy of Create_field
        created by the caller, not with the instance that was
        originally created during parsing. It's OK to create
        a temporary item and initialize with it a member of the
        copy -- this item will be thrown away along with the copy
        at the end of execution, and thus not introduce a dangling
        pointer in the parsed tree of a prepared statement or a
        stored procedure statement.
      */
      sql_field->def= sql_field->def->safe_charset_converter(save_cs);

      if (sql_field->def == NULL)
      {
        /* Could not convert */
        my_error(ER_INVALID_DEFAULT, MYF(0), sql_field->field_name);
        DBUG_RETURN(TRUE);
      }
    }

    if (sql_field->sql_type == MYSQL_TYPE_SET ||
        sql_field->sql_type == MYSQL_TYPE_ENUM)
    {
      uint32 dummy;
      CHARSET_INFO *cs= sql_field->charset;
      TYPELIB *interval= sql_field->interval;

      /*
        Create typelib from interval_list, and if necessary
        convert strings from client character set to the
        column character set.
      */
      if (!interval)
      {
        /*
          Create the typelib in runtime memory - we will free the
          occupied memory at the same time when we free this
          sql_field -- at the end of execution.
        */
        interval= sql_field->interval= typelib(thd->mem_root,
                                               sql_field->interval_list);
        List_iterator<String> int_it(sql_field->interval_list);
        String conv, *tmp;
        char comma_buf[5]; /* 5 bytes for 'filename' charset */
        DBUG_ASSERT(sizeof(comma_buf) >= cs->mbmaxlen);
        int comma_length= cs->cset->wc_mb(cs, ',', (uchar*) comma_buf,
                                          (uchar*) comma_buf +
                                          sizeof(comma_buf));
        DBUG_ASSERT(comma_length > 0);
        for (uint i= 0; (tmp= int_it++); i++)
        {
          size_t lengthsp;
          if (String::needs_conversion(tmp->length(), tmp->charset(),
                                       cs, &dummy))
          {
            uint cnv_errs;
            conv.copy(tmp->ptr(), tmp->length(), tmp->charset(), cs, &cnv_errs);
            interval->type_names[i]= strmake_root(thd->mem_root, conv.ptr(),
                                                  conv.length());
            interval->type_lengths[i]= conv.length();
          }

          // Strip trailing spaces.
          lengthsp= cs->cset->lengthsp(cs, interval->type_names[i],
                                       interval->type_lengths[i]);
          interval->type_lengths[i]= lengthsp;
          ((uchar *)interval->type_names[i])[lengthsp]= '\0';
          if (sql_field->sql_type == MYSQL_TYPE_SET)
          {
            if (cs->coll->instr(cs, interval->type_names[i], 
                                interval->type_lengths[i], 
                                comma_buf, comma_length, NULL, 0))
            {
              ErrConvString err(tmp->ptr(), tmp->length(), cs);
              my_error(ER_ILLEGAL_VALUE_FOR_TYPE, MYF(0), "set", err.ptr());
              DBUG_RETURN(TRUE);
            }
          }
        }
        sql_field->interval_list.empty(); // Don't need interval_list anymore
      }

      if (sql_field->sql_type == MYSQL_TYPE_SET)
      {
        uint32 field_length;
        if (sql_field->def != NULL)
        {
          char *not_used;
          uint not_used2;
          bool not_found= 0;
          String str, *def= sql_field->def->val_str(&str);
          if (def == NULL) /* SQL "NULL" maps to NULL */
          {
            if ((sql_field->flags & NOT_NULL_FLAG) != 0)
            {
              my_error(ER_INVALID_DEFAULT, MYF(0), sql_field->field_name);
              DBUG_RETURN(TRUE);
            }

            /* else, NULL is an allowed value */
            (void) find_set(interval, NULL, 0,
                            cs, &not_used, &not_used2, &not_found);
          }
          else /* not NULL */
          {
            (void) find_set(interval, def->ptr(), def->length(),
                            cs, &not_used, &not_used2, &not_found);
          }

          if (not_found)
          {
            my_error(ER_INVALID_DEFAULT, MYF(0), sql_field->field_name);
            DBUG_RETURN(TRUE);
          }
        }
        calculate_interval_lengths(cs, interval, &dummy, &field_length);
        sql_field->length= field_length + (interval->count - 1);
      }
      else  /* MYSQL_TYPE_ENUM */
      {
        uint32 field_length;
        DBUG_ASSERT(sql_field->sql_type == MYSQL_TYPE_ENUM);
        if (sql_field->def != NULL)
        {
          String str, *def= sql_field->def->val_str(&str);
          if (def == NULL) /* SQL "NULL" maps to NULL */
          {
            if ((sql_field->flags & NOT_NULL_FLAG) != 0)
            {
              my_error(ER_INVALID_DEFAULT, MYF(0), sql_field->field_name);
              DBUG_RETURN(TRUE);
            }

            /* else, the defaults yield the correct length for NULLs. */
          } 
          else /* not NULL */
          {
            def->length(cs->cset->lengthsp(cs, def->ptr(), def->length()));
            if (find_type2(interval, def->ptr(), def->length(), cs) == 0) /* not found */
            {
              my_error(ER_INVALID_DEFAULT, MYF(0), sql_field->field_name);
              DBUG_RETURN(TRUE);
            }
          }
        }
        calculate_interval_lengths(cs, interval, &field_length, &dummy);
        sql_field->length= field_length;
      }
      set_if_smaller(sql_field->length, MAX_FIELD_WIDTH-1);
    }

    if (sql_field->sql_type == MYSQL_TYPE_BIT)
    { 
      sql_field->pack_flag= FIELDFLAG_NUMBER;
      if (file->ha_table_flags() & HA_CAN_BIT_FIELD)
        total_uneven_bit_length+= sql_field->length & 7;
      else
        sql_field->pack_flag|= FIELDFLAG_TREAT_BIT_AS_CHAR;
    }

    sql_field->create_length_to_internal_length();
    if (prepare_blob_field(thd, sql_field))
      DBUG_RETURN(TRUE);

    if (!(sql_field->flags & NOT_NULL_FLAG))
      null_fields++;

    if (check_column_name(sql_field->field_name))
    {
      my_error(ER_WRONG_COLUMN_NAME, MYF(0), sql_field->field_name);
      DBUG_RETURN(TRUE);
    }

    /* Check if we have used the same field name before */
    for (dup_no=0; (dup_field=it2++) != sql_field; dup_no++)
    {
      if (my_strcasecmp(system_charset_info,
			sql_field->field_name,
			dup_field->field_name) == 0)
      {
	/*
	  If this was a CREATE ... SELECT statement, accept a field
	  redefinition if we are changing a field in the SELECT part
	*/
	if (field_no < select_field_pos || dup_no >= select_field_pos)
	{
	  my_error(ER_DUP_FIELDNAME, MYF(0), sql_field->field_name);
	  DBUG_RETURN(TRUE);
	}
	else
	{
	  /* Field redefined */

          /*
            If we are replacing a BIT field, revert the increment
            of total_uneven_bit_length that was done above.
          */
          if (sql_field->sql_type == MYSQL_TYPE_BIT &&
              file->ha_table_flags() & HA_CAN_BIT_FIELD)
            total_uneven_bit_length-= sql_field->length & 7;

	  sql_field->def=		dup_field->def;
	  sql_field->sql_type=		dup_field->sql_type;

          /*
            If we are replacing a field with a BIT field, we need
            to initialize pack_flag. Note that we do not need to
            increment total_uneven_bit_length here as this dup_field
            has already been processed.
          */
          if (sql_field->sql_type == MYSQL_TYPE_BIT)
          {
            sql_field->pack_flag= FIELDFLAG_NUMBER;
            if (!(file->ha_table_flags() & HA_CAN_BIT_FIELD))
              sql_field->pack_flag|= FIELDFLAG_TREAT_BIT_AS_CHAR;
          }

	  sql_field->charset=		(dup_field->charset ?
					 dup_field->charset :
					 create_info->default_table_charset);
	  sql_field->length=		dup_field->char_length;
          sql_field->pack_length=	dup_field->pack_length;
          sql_field->key_length=	dup_field->key_length;
	  sql_field->decimals=		dup_field->decimals;
	  sql_field->unireg_check=	dup_field->unireg_check;
          /* 
            We're making one field from two, the result field will have
            dup_field->flags as flags. If we've incremented null_fields
            because of sql_field->flags, decrement it back.
          */
          if (!(sql_field->flags & NOT_NULL_FLAG))
            null_fields--;
	  sql_field->flags=		dup_field->flags;
	  sql_field->create_length_to_internal_length();
          sql_field->interval=          dup_field->interval;
          sql_field->vcol_info=         dup_field->vcol_info;
          sql_field->stored_in_db=      dup_field->stored_in_db;
	  it2.remove();			// Remove first (create) definition
	  select_field_pos--;
	  break;
	}
      }
    }
    /* Don't pack rows in old tables if the user has requested this */
    if ((sql_field->flags & BLOB_FLAG) ||
	(sql_field->sql_type == MYSQL_TYPE_VARCHAR &&
         create_info->row_type != ROW_TYPE_FIXED))
      (*db_options)|= HA_OPTION_PACK_RECORD;
    it2.rewind();
  }

  /* record_offset will be increased with 'length-of-null-bits' later */
  record_offset= 0;
  null_fields+= total_uneven_bit_length;

  it.rewind();
  while ((sql_field=it++))
  {
    DBUG_ASSERT(sql_field->charset != 0);

    if (prepare_create_field(sql_field, &blob_columns, 
			     &timestamps, &timestamps_with_niladic,
			     file->ha_table_flags()))
      DBUG_RETURN(TRUE);
    if (sql_field->sql_type == MYSQL_TYPE_VARCHAR)
      create_info->varchar= TRUE;
    sql_field->offset= record_offset;
    if (MTYP_TYPENR(sql_field->unireg_check) == Field::NEXT_NUMBER)
      auto_increment++;
    if (parse_option_list(thd, &sql_field->option_struct,
                          sql_field->option_list,
                          create_info->db_type->field_options, FALSE,
                          thd->mem_root))
      DBUG_RETURN(TRUE);
    /*
      For now skip fields that are not physically stored in the database
      (virtual fields) and update their offset later 
      (see the next loop).
    */
    if (sql_field->stored_in_db)
      record_offset+= sql_field->pack_length;
  }
  /* Update virtual fields' offset*/
  it.rewind();
  while ((sql_field=it++))
  {
    if (!sql_field->stored_in_db)
    {
      sql_field->offset= record_offset;
      record_offset+= sql_field->pack_length;
    }
  }
  if (timestamps_with_niladic > 1)
  {
    my_message(ER_TOO_MUCH_AUTO_TIMESTAMP_COLS,
               ER(ER_TOO_MUCH_AUTO_TIMESTAMP_COLS), MYF(0));
    DBUG_RETURN(TRUE);
  }
  if (auto_increment > 1)
  {
    my_message(ER_WRONG_AUTO_KEY, ER(ER_WRONG_AUTO_KEY), MYF(0));
    DBUG_RETURN(TRUE);
  }
  if (auto_increment &&
      (file->ha_table_flags() & HA_NO_AUTO_INCREMENT))
  {
    my_message(ER_TABLE_CANT_HANDLE_AUTO_INCREMENT,
               ER(ER_TABLE_CANT_HANDLE_AUTO_INCREMENT), MYF(0));
    DBUG_RETURN(TRUE);
  }

  if (blob_columns && (file->ha_table_flags() & HA_NO_BLOBS))
  {
    my_message(ER_TABLE_CANT_HANDLE_BLOB, ER(ER_TABLE_CANT_HANDLE_BLOB),
               MYF(0));
    DBUG_RETURN(TRUE);
  }

  /*
   CREATE TABLE[with auto_increment column] SELECT is unsafe as the rows
   inserted in the created table depends on the order of the rows fetched
   from the select tables. This order may differ on master and slave. We
   therefore mark it as unsafe.
  */
  if (select_field_count > 0 && auto_increment)
  thd->lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_CREATE_SELECT_AUTOINC);

  /* Create keys */

  List_iterator<Key> key_iterator(alter_info->key_list);
  List_iterator<Key> key_iterator2(alter_info->key_list);
  uint key_parts=0, fk_key_count=0;
  bool primary_key=0,unique_key=0;
  Key *key, *key2;
  uint tmp, key_number;
  /* special marker for keys to be ignored */
  static char ignore_key[1];

  /* Calculate number of key segements */
  *key_count= 0;

  while ((key=key_iterator++))
  {
    DBUG_PRINT("info", ("key name: '%s'  type: %d", key->name.str ? key->name.str :
                        "(none)" , key->type));
    if (key->type == Key::FOREIGN_KEY)
    {
      fk_key_count++;
      if (((Foreign_key *)key)->validate(alter_info->create_list))
        DBUG_RETURN(TRUE);
      Foreign_key *fk_key= (Foreign_key*) key;
      if (fk_key->ref_columns.elements &&
	  fk_key->ref_columns.elements != fk_key->columns.elements)
      {
        my_error(ER_WRONG_FK_DEF, MYF(0),
                 (fk_key->name.str ? fk_key->name.str :
                                     "foreign key without name"),
                 ER(ER_KEY_REF_DO_NOT_MATCH_TABLE_REF));
	DBUG_RETURN(TRUE);
      }
      continue;
    }
    (*key_count)++;
    tmp=file->max_key_parts();
    if (key->columns.elements > tmp)
    {
      my_error(ER_TOO_MANY_KEY_PARTS,MYF(0),tmp);
      DBUG_RETURN(TRUE);
    }
    if (check_ident_length(&key->name))
      DBUG_RETURN(TRUE);
    key_iterator2.rewind ();
    if (key->type != Key::FOREIGN_KEY)
    {
      while ((key2 = key_iterator2++) != key)
      {
	/*
          foreign_key_prefix(key, key2) returns 0 if key or key2, or both, is
          'generated', and a generated key is a prefix of the other key.
          Then we do not need the generated shorter key.
        */
        if ((key2->type != Key::FOREIGN_KEY &&
             key2->name.str != ignore_key &&
             !foreign_key_prefix(key, key2)))
        {
          /* TODO: issue warning message */
          /* mark that the generated key should be ignored */
          if (!key2->generated ||
              (key->generated && key->columns.elements <
               key2->columns.elements))
            key->name.str= ignore_key;
          else
          {
            key2->name.str= ignore_key;
            key_parts-= key2->columns.elements;
            (*key_count)--;
          }
          break;
        }
      }
    }
    if (key->name.str != ignore_key)
      key_parts+=key->columns.elements;
    else
      (*key_count)--;
    if (key->name.str && !tmp_table && (key->type != Key::PRIMARY) &&
	!my_strcasecmp(system_charset_info, key->name.str, primary_key_name))
    {
      my_error(ER_WRONG_NAME_FOR_INDEX, MYF(0), key->name.str);
      DBUG_RETURN(TRUE);
    }
  }
  tmp=file->max_keys();
  if (*key_count > tmp)
  {
    my_error(ER_TOO_MANY_KEYS,MYF(0),tmp);
    DBUG_RETURN(TRUE);
  }

  (*key_info_buffer)= key_info= (KEY*) sql_calloc(sizeof(KEY) * (*key_count));
  key_part_info=(KEY_PART_INFO*) sql_calloc(sizeof(KEY_PART_INFO)*key_parts);
  if (!*key_info_buffer || ! key_part_info)
    DBUG_RETURN(TRUE);				// Out of memory

  key_iterator.rewind();
  key_number=0;
  for (; (key=key_iterator++) ; key_number++)
  {
    uint key_length=0;
    Key_part_spec *column;

    if (key->name.str == ignore_key)
    {
      /* ignore redundant keys */
      do
	key=key_iterator++;
      while (key && key->name.str == ignore_key);
      if (!key)
	break;
    }

    switch (key->type) {
    case Key::MULTIPLE:
	key_info->flags= 0;
	break;
    case Key::FULLTEXT:
	key_info->flags= HA_FULLTEXT;
	if ((key_info->parser_name= &key->key_create_info.parser_name)->str)
          key_info->flags|= HA_USES_PARSER;
        else
          key_info->parser_name= 0;
	break;
    case Key::SPATIAL:
#ifdef HAVE_SPATIAL
	key_info->flags= HA_SPATIAL;
	break;
#else
	my_error(ER_FEATURE_DISABLED, MYF(0),
                 sym_group_geom.name, sym_group_geom.needed_define);
	DBUG_RETURN(TRUE);
#endif
    case Key::FOREIGN_KEY:
      key_number--;				// Skip this key
      continue;
    default:
      key_info->flags = HA_NOSAME;
      break;
    }
    if (key->generated)
      key_info->flags|= HA_GENERATED_KEY;

    key_info->key_parts=(uint8) key->columns.elements;
    key_info->key_part=key_part_info;
    key_info->usable_key_parts= key_number;
    key_info->algorithm= key->key_create_info.algorithm;
    key_info->option_list= key->option_list;
    if (parse_option_list(thd, &key_info->option_struct,
                          key_info->option_list,
                          create_info->db_type->index_options, FALSE,
                          thd->mem_root))
      DBUG_RETURN(TRUE);

    if (key->type == Key::FULLTEXT)
    {
      if (!(file->ha_table_flags() & HA_CAN_FULLTEXT))
      {
	my_message(ER_TABLE_CANT_HANDLE_FT, ER(ER_TABLE_CANT_HANDLE_FT),
                   MYF(0));
	DBUG_RETURN(TRUE);
      }
    }
    /*
       Make SPATIAL to be RTREE by default
       SPATIAL only on BLOB or at least BINARY, this
       actually should be replaced by special GEOM type
       in near future when new frm file is ready
       checking for proper key parts number:
    */

    /* TODO: Add proper checks if handler supports key_type and algorithm */
    if (key_info->flags & HA_SPATIAL)
    {
      if (!(file->ha_table_flags() & HA_CAN_RTREEKEYS))
      {
        my_message(ER_TABLE_CANT_HANDLE_SPKEYS, ER(ER_TABLE_CANT_HANDLE_SPKEYS),
                   MYF(0));
        DBUG_RETURN(TRUE);
      }
      if (key_info->key_parts != 1)
      {
	my_error(ER_WRONG_ARGUMENTS, MYF(0), "SPATIAL INDEX");
	DBUG_RETURN(TRUE);
      }
    }
    else if (key_info->algorithm == HA_KEY_ALG_RTREE)
    {
#ifdef HAVE_RTREE_KEYS
      if ((key_info->key_parts & 1) == 1)
      {
	my_error(ER_WRONG_ARGUMENTS, MYF(0), "RTREE INDEX");
	DBUG_RETURN(TRUE);
      }
      /* TODO: To be deleted */
      my_error(ER_NOT_SUPPORTED_YET, MYF(0), "RTREE INDEX");
      DBUG_RETURN(TRUE);
#else
      my_error(ER_FEATURE_DISABLED, MYF(0),
               sym_group_rtree.name, sym_group_rtree.needed_define);
      DBUG_RETURN(TRUE);
#endif
    }

    /* Take block size from key part or table part */
    /*
      TODO: Add warning if block size changes. We can't do it here, as
      this may depend on the size of the key
    */
    key_info->block_size= (key->key_create_info.block_size ?
                           key->key_create_info.block_size :
                           create_info->key_block_size);

    if (key_info->block_size)
      key_info->flags|= HA_USES_BLOCK_SIZE;

    List_iterator<Key_part_spec> cols(key->columns), cols2(key->columns);
    CHARSET_INFO *ft_key_charset=0;  // for FULLTEXT
    for (uint column_nr=0 ; (column=cols++) ; column_nr++)
    {
      Key_part_spec *dup_column;

      it.rewind();
      field=0;
      while ((sql_field=it++) &&
	     my_strcasecmp(system_charset_info,
			   column->field_name.str,
			   sql_field->field_name))
	field++;
      if (!sql_field)
      {
	my_error(ER_KEY_COLUMN_DOES_NOT_EXITS, MYF(0), column->field_name.str);
	DBUG_RETURN(TRUE);
      }
      while ((dup_column= cols2++) != column)
      {
        if (!my_strcasecmp(system_charset_info,
	     	           column->field_name.str, dup_column->field_name.str))
	{
	  my_printf_error(ER_DUP_FIELDNAME,
			  ER(ER_DUP_FIELDNAME),MYF(0),
			  column->field_name.str);
	  DBUG_RETURN(TRUE);
	}
      }
      cols2.rewind();
      if (key->type == Key::FULLTEXT)
      {
	if ((sql_field->sql_type != MYSQL_TYPE_STRING &&
	     sql_field->sql_type != MYSQL_TYPE_VARCHAR &&
	     !f_is_blob(sql_field->pack_flag)) ||
	    sql_field->charset == &my_charset_bin ||
	    sql_field->charset->mbminlen > 1 || // ucs2 doesn't work yet
	    (ft_key_charset && sql_field->charset != ft_key_charset))
	{
	    my_error(ER_BAD_FT_COLUMN, MYF(0), column->field_name.str);
	    DBUG_RETURN(-1);
	}
	ft_key_charset=sql_field->charset;
	/*
	  for fulltext keys keyseg length is 1 for blobs (it's ignored in ft
	  code anyway, and 0 (set to column width later) for char's. it has
	  to be correct col width for char's, as char data are not prefixed
	  with length (unlike blobs, where ft code takes data length from a
	  data prefix, ignoring column->length).
	*/
	column->length=test(f_is_blob(sql_field->pack_flag));
      }
      else
      {
	column->length*= sql_field->charset->mbmaxlen;

        if (key->type == Key::SPATIAL)
        {
          if (column->length)
          {
            my_error(ER_WRONG_SUB_KEY, MYF(0));
            DBUG_RETURN(TRUE);
          }
          if (!f_is_geom(sql_field->pack_flag))
          {
            my_error(ER_WRONG_ARGUMENTS, MYF(0), "SPATIAL INDEX");
            DBUG_RETURN(TRUE);
          }
        }

	if (f_is_blob(sql_field->pack_flag) ||
            (f_is_geom(sql_field->pack_flag) && key->type != Key::SPATIAL))
	{
	  if (!(file->ha_table_flags() & HA_CAN_INDEX_BLOBS))
	  {
	    my_error(ER_BLOB_USED_AS_KEY, MYF(0), column->field_name.str);
	    DBUG_RETURN(TRUE);
	  }
          if (f_is_geom(sql_field->pack_flag) && sql_field->geom_type ==
              Field::GEOM_POINT)
            column->length= MAX_LEN_GEOM_POINT_FIELD;
	  if (!column->length)
	  {
	    my_error(ER_BLOB_KEY_WITHOUT_LENGTH, MYF(0), column->field_name.str);
	    DBUG_RETURN(TRUE);
	  }
	}
#ifdef HAVE_SPATIAL
	if (key->type == Key::SPATIAL)
	{
	  if (!column->length)
	  {
	    /*
              4 is: (Xmin,Xmax,Ymin,Ymax), this is for 2D case
              Lately we'll extend this code to support more dimensions
	    */
	    column->length= 4*sizeof(double);
	  }
	}
#endif
        if (!sql_field->stored_in_db)
        {
          /* Key fields must always be physically stored. */
          my_error(ER_KEY_BASED_ON_GENERATED_VIRTUAL_COLUMN, MYF(0));
          DBUG_RETURN(TRUE);
        }
        if (key->type == Key::PRIMARY && sql_field->vcol_info)
        {
          my_error(ER_PRIMARY_KEY_BASED_ON_VIRTUAL_COLUMN, MYF(0));
          DBUG_RETURN(TRUE);
        }
	if (!(sql_field->flags & NOT_NULL_FLAG))
	{
	  if (key->type == Key::PRIMARY)
	  {
	    /* Implicitly set primary key fields to NOT NULL for ISO conf. */
	    sql_field->flags|= NOT_NULL_FLAG;
	    sql_field->pack_flag&= ~FIELDFLAG_MAYBE_NULL;
            null_fields--;
	  }
	  else
          {
            key_info->flags|= HA_NULL_PART_KEY;
            if (!(file->ha_table_flags() & HA_NULL_IN_KEY))
            {
              my_error(ER_NULL_COLUMN_IN_INDEX, MYF(0), column->field_name.str);
              DBUG_RETURN(TRUE);
            }
            if (key->type == Key::SPATIAL)
            {
              my_message(ER_SPATIAL_CANT_HAVE_NULL,
                         ER(ER_SPATIAL_CANT_HAVE_NULL), MYF(0));
              DBUG_RETURN(TRUE);
            }
          }
	}
	if (MTYP_TYPENR(sql_field->unireg_check) == Field::NEXT_NUMBER)
	{
	  if (column_nr == 0 || (file->ha_table_flags() & HA_AUTO_PART_KEY))
	    auto_increment--;			// Field is used
	}
      }

      key_part_info->fieldnr= field;
      key_part_info->offset=  (uint16) sql_field->offset;
      key_part_info->key_type=sql_field->pack_flag;
      uint key_part_length= sql_field->key_length;

      if (column->length)
      {
	if (f_is_blob(sql_field->pack_flag))
	{
	  key_part_length= min(column->length,
                               blob_length_by_type(sql_field->sql_type)
                               * sql_field->charset->mbmaxlen);
	  if (key_part_length > max_key_length ||
	      key_part_length > file->max_key_part_length())
	  {
	    key_part_length= min(max_key_length, file->max_key_part_length());
	    if (key->type == Key::MULTIPLE)
	    {
	      /* not a critical problem */
	      push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
		           ER_TOO_LONG_KEY, ER(ER_TOO_LONG_KEY),
		           key_part_length);
              /* Align key length to multibyte char boundary */
              key_part_length-= key_part_length % sql_field->charset->mbmaxlen;
	    }
	    else
	    {
	      my_error(ER_TOO_LONG_KEY, MYF(0), key_part_length);
	      DBUG_RETURN(TRUE);
	    }
	  }
	}
        // Catch invalid use of partial keys 
	else if (!f_is_geom(sql_field->pack_flag) &&
                 // is the key partial? 
                 column->length != key_part_length &&
                 // is prefix length bigger than field length? 
                 (column->length > key_part_length ||
                  // can the field have a partial key? 
                  !Field::type_can_have_key_part (sql_field->sql_type) ||
                  // a packed field can't be used in a partial key
                  f_is_packed(sql_field->pack_flag) ||
                  // does the storage engine allow prefixed search?
                  ((file->ha_table_flags() & HA_NO_PREFIX_CHAR_KEYS) &&
                   // and is this a 'unique' key?
                   (key_info->flags & HA_NOSAME))))
        {
	  my_message(ER_WRONG_SUB_KEY, ER(ER_WRONG_SUB_KEY), MYF(0));
	  DBUG_RETURN(TRUE);
	}
	else if (!(file->ha_table_flags() & HA_NO_PREFIX_CHAR_KEYS))
	  key_part_length= column->length;
      }
      else if (key_part_length == 0 && (sql_field->flags & NOT_NULL_FLAG))
      {
	my_error(ER_WRONG_KEY_COLUMN, MYF(0), column->field_name.str);
	  DBUG_RETURN(TRUE);
      }
      if (key_part_length > file->max_key_part_length() &&
          key->type != Key::FULLTEXT)
      {
        key_part_length= file->max_key_part_length();
	if (key->type == Key::MULTIPLE)
	{
	  /* not a critical problem */
	  push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
		       ER_TOO_LONG_KEY, ER(ER_TOO_LONG_KEY),
		       key_part_length);
          /* Align key length to multibyte char boundary */
          key_part_length-= key_part_length % sql_field->charset->mbmaxlen;
	}
	else
	{
	  my_error(ER_TOO_LONG_KEY, MYF(0), key_part_length);
	  DBUG_RETURN(TRUE);
	}
      }
      key_part_info->length= (uint16) key_part_length;
      /* Use packed keys for long strings on the first column */
      if (!((*db_options) & HA_OPTION_NO_PACK_KEYS) &&
          !((create_info->table_options & HA_OPTION_NO_PACK_KEYS)) &&
          (key_part_length >= KEY_DEFAULT_PACK_LENGTH &&
           (sql_field->sql_type == MYSQL_TYPE_STRING ||
            sql_field->sql_type == MYSQL_TYPE_VARCHAR ||
            f_is_blob(sql_field->pack_flag))))
      {
        if ((column_nr == 0 && f_is_blob(sql_field->pack_flag)) ||
            sql_field->sql_type == MYSQL_TYPE_VARCHAR)
          key_info->flags|= HA_BINARY_PACK_KEY | HA_VAR_LENGTH_KEY;
        else
          key_info->flags|= HA_PACK_KEY;
      }
      /* Check if the key segment is partial, set the key flag accordingly */
      if (key_part_length != sql_field->key_length)
        key_info->flags|= HA_KEY_HAS_PART_KEY_SEG;

      key_length+= key_part_length;
      key_part_info++;

      /* Create the key name based on the first column (if not given) */
      if (column_nr == 0)
      {
	if (key->type == Key::PRIMARY)
	{
	  if (primary_key)
	  {
	    my_message(ER_MULTIPLE_PRI_KEY, ER(ER_MULTIPLE_PRI_KEY),
                       MYF(0));
	    DBUG_RETURN(TRUE);
	  }
	  key_name=primary_key_name;
	  primary_key=1;
	}
	else if (!(key_name= key->name.str))
	  key_name=make_unique_key_name(sql_field->field_name,
					*key_info_buffer, key_info);
	if (check_if_keyname_exists(key_name, *key_info_buffer, key_info))
	{
	  my_error(ER_DUP_KEYNAME, MYF(0), key_name);
	  DBUG_RETURN(TRUE);
	}
	key_info->name=(char*) key_name;
      }
    }
    if (!key_info->name || check_column_name(key_info->name))
    {
      my_error(ER_WRONG_NAME_FOR_INDEX, MYF(0), key_info->name);
      DBUG_RETURN(TRUE);
    }
    if (!(key_info->flags & HA_NULL_PART_KEY))
      unique_key=1;
    key_info->key_length=(uint16) key_length;
    if (key_length > max_key_length && key->type != Key::FULLTEXT)
    {
      my_error(ER_TOO_LONG_KEY,MYF(0),max_key_length);
      DBUG_RETURN(TRUE);
    }

    uint tmp_len= system_charset_info->cset->charpos(system_charset_info,
                                           key->key_create_info.comment.str,
                                           key->key_create_info.comment.str +
                                           key->key_create_info.comment.length,
                                           INDEX_COMMENT_MAXLEN);

    if (tmp_len < key->key_create_info.comment.length)
    {
      if ((thd->variables.sql_mode &
           (MODE_STRICT_TRANS_TABLES | MODE_STRICT_ALL_TABLES)))
      {
        my_error(ER_TOO_LONG_INDEX_COMMENT, MYF(0),
                 key_info->name, static_cast<ulong>(INDEX_COMMENT_MAXLEN));
        DBUG_RETURN(-1);
      }
      char warn_buff[MYSQL_ERRMSG_SIZE];
      my_snprintf(warn_buff, sizeof(warn_buff), ER(ER_TOO_LONG_INDEX_COMMENT),
                  key_info->name, static_cast<ulong>(INDEX_COMMENT_MAXLEN));
      /* do not push duplicate warnings */
      if (!check_duplicate_warning(thd, warn_buff, strlen(warn_buff)))
        push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                     ER_TOO_LONG_INDEX_COMMENT, warn_buff);

      key->key_create_info.comment.length= tmp_len;
    }

    key_info->comment.length= key->key_create_info.comment.length;
    if (key_info->comment.length > 0)
    {
      key_info->flags|= HA_USES_COMMENT;
      key_info->comment.str= key->key_create_info.comment.str;
    }

    key_info++;
  }
  if (!unique_key && !primary_key &&
      (file->ha_table_flags() & HA_REQUIRE_PRIMARY_KEY))
  {
    my_message(ER_REQUIRES_PRIMARY_KEY, ER(ER_REQUIRES_PRIMARY_KEY), MYF(0));
    DBUG_RETURN(TRUE);
  }
  if (auto_increment > 0)
  {
    my_message(ER_WRONG_AUTO_KEY, ER(ER_WRONG_AUTO_KEY), MYF(0));
    DBUG_RETURN(TRUE);
  }
  /* Sort keys in optimized order */
  my_qsort((uchar*) *key_info_buffer, *key_count, sizeof(KEY),
	   (qsort_cmp) sort_keys);
  create_info->null_bits= null_fields;

  /* Check fields. */
  it.rewind();
  while ((sql_field=it++))
  {
    Field::utype type= (Field::utype) MTYP_TYPENR(sql_field->unireg_check);

    if (thd->variables.sql_mode & MODE_NO_ZERO_DATE &&
        !sql_field->def && !sql_field->vcol_info &&
        sql_field->sql_type == MYSQL_TYPE_TIMESTAMP &&
        (sql_field->flags & NOT_NULL_FLAG) &&
        (type == Field::NONE || type == Field::TIMESTAMP_UN_FIELD))
    {
      /*
        An error should be reported if:
          - NO_ZERO_DATE SQL mode is active;
          - there is no explicit DEFAULT clause (default column value);
          - this is a TIMESTAMP column;
          - the column is not NULL;
          - this is not the DEFAULT CURRENT_TIMESTAMP column.

        In other words, an error should be reported if
          - NO_ZERO_DATE SQL mode is active;
          - the column definition is equivalent to
            'column_name TIMESTAMP DEFAULT 0'.
      */

      my_error(ER_INVALID_DEFAULT, MYF(0), sql_field->field_name);
      DBUG_RETURN(TRUE);
    }
  }

  if (parse_option_list(thd, &create_info->option_struct,
                          create_info->option_list,
                          file->partition_ht()->table_options, FALSE,
                          thd->mem_root))
      DBUG_RETURN(TRUE);

  DBUG_RETURN(FALSE);
}


/*
  Set table default charset, if not set

  SYNOPSIS
    set_table_default_charset()
    create_info        Table create information

  DESCRIPTION
    If the table character set was not given explicitely,
    let's fetch the database default character set and
    apply it to the table.
*/

static void set_table_default_charset(THD *thd,
				      HA_CREATE_INFO *create_info, char *db)
{
  /*
    If the table character set was not given explicitly,
    let's fetch the database default character set and
    apply it to the table.
  */
  if (!create_info->default_table_charset)
  {
    HA_CREATE_INFO db_info;

    load_db_opt_by_name(thd, db, &db_info);

    create_info->default_table_charset= db_info.default_table_charset;
  }
}


/*
  Extend long VARCHAR fields to blob & prepare field if it's a blob

  SYNOPSIS
    prepare_blob_field()
    sql_field		Field to check

  RETURN
    0	ok
    1	Error (sql_field can't be converted to blob)
        In this case the error is given
*/

static bool prepare_blob_field(THD *thd, Create_field *sql_field)
{
  DBUG_ENTER("prepare_blob_field");

  if (sql_field->length > MAX_FIELD_VARCHARLENGTH &&
      !(sql_field->flags & BLOB_FLAG))
  {
    /* Convert long VARCHAR columns to TEXT or BLOB */
    char warn_buff[MYSQL_ERRMSG_SIZE];

    if (sql_field->def || (thd->variables.sql_mode & (MODE_STRICT_TRANS_TABLES |
                                                      MODE_STRICT_ALL_TABLES)))
    {
      my_error(ER_TOO_BIG_FIELDLENGTH, MYF(0), sql_field->field_name,
               static_cast<ulong>(MAX_FIELD_VARCHARLENGTH /
                                  sql_field->charset->mbmaxlen));
      DBUG_RETURN(1);
    }
    sql_field->sql_type= MYSQL_TYPE_BLOB;
    sql_field->flags|= BLOB_FLAG;
    my_snprintf(warn_buff, sizeof(warn_buff), ER(ER_AUTO_CONVERT), sql_field->field_name,
            (sql_field->charset == &my_charset_bin) ? "VARBINARY" : "VARCHAR",
            (sql_field->charset == &my_charset_bin) ? "BLOB" : "TEXT");
    push_warning(thd, MYSQL_ERROR::WARN_LEVEL_NOTE, ER_AUTO_CONVERT,
                 warn_buff);
  }

  if ((sql_field->flags & BLOB_FLAG) && sql_field->length)
  {
    if (sql_field->sql_type == FIELD_TYPE_BLOB ||
        sql_field->sql_type == FIELD_TYPE_TINY_BLOB ||
        sql_field->sql_type == FIELD_TYPE_MEDIUM_BLOB)
    {
      /* The user has given a length to the blob column */
      sql_field->sql_type= get_blob_type_from_length(sql_field->length);
      sql_field->pack_length= calc_pack_length(sql_field->sql_type, 0);
    }
    sql_field->length= 0;
  }
  DBUG_RETURN(0);
}


/*
  Preparation of Create_field for SP function return values.
  Based on code used in the inner loop of mysql_prepare_create_table()
  above.

  SYNOPSIS
    sp_prepare_create_field()
    thd			Thread object
    sql_field		Field to prepare

  DESCRIPTION
    Prepares the field structures for field creation.

*/

void sp_prepare_create_field(THD *thd, Create_field *sql_field)
{
  if (sql_field->sql_type == MYSQL_TYPE_SET ||
      sql_field->sql_type == MYSQL_TYPE_ENUM)
  {
    uint32 field_length, dummy;
    if (sql_field->sql_type == MYSQL_TYPE_SET)
    {
      calculate_interval_lengths(sql_field->charset,
                                 sql_field->interval, &dummy, 
                                 &field_length);
      sql_field->length= field_length + 
                         (sql_field->interval->count - 1);
    }
    else /* MYSQL_TYPE_ENUM */
    {
      calculate_interval_lengths(sql_field->charset,
                                 sql_field->interval,
                                 &field_length, &dummy);
      sql_field->length= field_length;
    }
    set_if_smaller(sql_field->length, MAX_FIELD_WIDTH-1);
  }

  if (sql_field->sql_type == MYSQL_TYPE_BIT)
  {
    sql_field->pack_flag= FIELDFLAG_NUMBER |
                          FIELDFLAG_TREAT_BIT_AS_CHAR;
  }
  sql_field->create_length_to_internal_length();
  DBUG_ASSERT(sql_field->def == 0);
  /* Can't go wrong as sql_field->def is not defined */
  (void) prepare_blob_field(thd, sql_field);
}


#ifdef WITH_PARTITION_STORAGE_ENGINE
/**
  Auxiliary function which allows to check if freshly created .FRM
  file for table can be opened.

  @retval FALSE - Success.
  @retval TRUE  - Failure.
*/

static bool check_if_created_table_can_be_opened(THD *thd,
                                                 const char *path,
                                                 const char *db,
                                                 const char *table_name,
                                                 HA_CREATE_INFO *create_info,
                                                 handler *file)
{
  TABLE table;
  TABLE_SHARE share;
  bool result;

  /*
    It is impossible to open definition of partitioned table without .par file.
  */
  if (file->ha_create_handler_files(path, NULL, CHF_CREATE_FLAG, create_info))
    return TRUE;

  init_tmp_table_share(thd, &share, db, 0, table_name, path);

  result= (open_table_def(thd, &share, 0) ||
           open_table_from_share(thd, &share, "", 0, (uint) READ_ALL,
                                 0, &table, TRUE));
  /*
    Assert that the change list is empty as no partition function currently
    needs to modify item tree. May need call THD::rollback_item_tree_changes
    later before calling closefrm if the change list is not empty.
  */
  DBUG_ASSERT(thd->change_list.is_empty());
  if (! result)
    (void) closefrm(&table, 0);

  free_table_share(&share);
  (void) file->ha_create_handler_files(path, NULL, CHF_DELETE_FLAG, create_info);
  return result;
}
#endif


/**
  Check that there is no frm file for given table

  @param old_path        path to the old frm file
  @param path            path to the frm file in new encoding
  @param db              database name
  @param table_name      table name
  @param alias           table name for error message (for new encoding)
  @param issue_error     should we issue error messages

  @retval FALSE there is no frm file
  @retval TRUE  there is frm file
*/

bool check_table_file_presence(char *old_path,
                               char *path,
                               const char *db,
                               const char *table_name,
                               const char *alias,
                               bool issue_error)
{
  if (!access(path,F_OK))
  {
    if (issue_error)
      my_error(ER_TABLE_EXISTS_ERROR,MYF(0),alias);
    return TRUE;
  }
  {
    /*
      Check if file of the table in 5.0 file name encoding exists.

      Except case when it is the same table.
    */
    char tbl50[FN_REFLEN];
#ifdef _WIN32
    if (check_if_legal_tablename(table_name) != 0)
    {
      /*
       Check for reserved device names for which access() returns 0
       (CON, AUX etc).
      */
      return FALSE;
    }
#endif
    strxmov(tbl50, mysql_data_home, "/", db, "/", table_name, NullS);
    fn_format(tbl50, tbl50, "", reg_ext, MY_UNPACK_FILENAME);
    if (!access(tbl50, F_OK) &&
        (old_path == NULL ||
         strcmp(old_path, tbl50) != 0))
    {
      if (issue_error)
      {
        strxmov(tbl50, MYSQL50_TABLE_NAME_PREFIX, table_name, NullS);
        my_error(ER_TABLE_EXISTS_ERROR, MYF(0), tbl50);
      }
      return TRUE;
    }
  }
  return FALSE;
}


/*
  Create a table

  SYNOPSIS
    mysql_create_table_no_lock()
    thd			Thread object
    db			Database
    table_name		Table name
    create_info	        Create information (like MAX_ROWS)
    fields		List of fields to create
    keys		List of keys to create
    internal_tmp_table  Set to 1 if this is an internal temporary table
			(From ALTER TABLE)
    select_field_count
    is_trans            identifies the type of engine where the table
                        was created: either trans or non-trans.

  DESCRIPTION
    If one creates a temporary table, this is automatically opened

    Note that this function assumes that caller already have taken
    exclusive metadata lock on table being created or used some other
    way to ensure that concurrent operations won't intervene.
    mysql_create_table() is a wrapper that can be used for this.

    no_log is needed for the case of CREATE ... SELECT,
    as the logging will be done later in sql_insert.cc
    select_field_count is also used for CREATE ... SELECT,
    and must be zero for standard create of table.

  RETURN VALUES
    FALSE OK
    TRUE  error
*/

bool mysql_create_table_no_lock(THD *thd,
                                const char *db, const char *table_name,
                                HA_CREATE_INFO *create_info,
                                Alter_info *alter_info,
                                bool internal_tmp_table,
                                uint select_field_count,
                                bool *is_trans)
{
  char		path[FN_REFLEN + 1];
  uint          path_length;
  const char	*alias;
  uint		db_options, key_count;
  KEY		*key_info_buffer;
  handler	*file;
  bool		error= TRUE;
  DBUG_ENTER("mysql_create_table_no_lock");
  DBUG_PRINT("enter", ("db: '%s'  table: '%s'  tmp: %d",
                       db, table_name, internal_tmp_table));


  /* Check for duplicate fields and check type of table to create */
  if (!alter_info->create_list.elements)
  {
    my_message(ER_TABLE_MUST_HAVE_COLUMNS, ER(ER_TABLE_MUST_HAVE_COLUMNS),
               MYF(0));
    DBUG_RETURN(TRUE);
  }
  if (check_engine(thd, db, table_name, create_info))
    DBUG_RETURN(TRUE);

  set_table_default_charset(thd, create_info, (char*) db);

  db_options= create_info->table_options;
  if (!create_info->frm_only &&
      create_info->row_type != ROW_TYPE_FIXED &&
      create_info->row_type != ROW_TYPE_DEFAULT)
    db_options|= HA_OPTION_PACK_RECORD;
  alias= table_case_name(create_info, table_name);
  if (!(file= get_new_handler((TABLE_SHARE*) 0, thd->mem_root,
                              create_info->db_type)))
  {
    mem_alloc_error(sizeof(handler));
    DBUG_RETURN(TRUE);
  }
#ifdef WITH_PARTITION_STORAGE_ENGINE
  partition_info *part_info= thd->work_part_info;

  if (!part_info && create_info->db_type->partition_flags &&
      (create_info->db_type->partition_flags() & HA_USE_AUTO_PARTITION))
  {
    /*
      Table is not defined as a partitioned table but the engine handles
      all tables as partitioned. The handler will set up the partition info
      object with the default settings.
    */
    thd->work_part_info= part_info= new partition_info();
    if (!part_info)
    {
      mem_alloc_error(sizeof(partition_info));
      DBUG_RETURN(TRUE);
    }
    file->set_auto_partitions(part_info);
    part_info->default_engine_type= create_info->db_type;
    part_info->is_auto_partitioned= TRUE;
  }
  if (part_info)
  {
    /*
      The table has been specified as a partitioned table.
      If this is part of an ALTER TABLE the handler will be the partition
      handler but we need to specify the default handler to use for
      partitions also in the call to check_partition_info. We transport
      this information in the default_db_type variable, it is either
      DB_TYPE_DEFAULT or the engine set in the ALTER TABLE command.

      Check that we don't use foreign keys in the table since it won't
      work even with InnoDB beneath it.
    */
    List_iterator<Key> key_iterator(alter_info->key_list);
    Key *key;
    handlerton *part_engine_type= create_info->db_type;
    char *part_syntax_buf;
    uint syntax_len;
    handlerton *engine_type;
    if (create_info->options & HA_LEX_CREATE_TMP_TABLE)
    {
      my_error(ER_PARTITION_NO_TEMPORARY, MYF(0));
      goto err;
    }
    while ((key= key_iterator++))
    {
      if (key->type == Key::FOREIGN_KEY &&
          !part_info->is_auto_partitioned)
      {
        my_error(ER_FOREIGN_KEY_ON_PARTITIONED, MYF(0));
        goto err;
      }
    }
    if ((part_engine_type == partition_hton) &&
        part_info->default_engine_type)
    {
      /*
        This only happens at ALTER TABLE.
        default_engine_type was assigned from the engine set in the ALTER
        TABLE command.
      */
      ;
    }
    else
    {
      if (create_info->used_fields & HA_CREATE_USED_ENGINE)
      {
        part_info->default_engine_type= create_info->db_type;
      }
      else
      {
        if (part_info->default_engine_type == NULL)
        {
          part_info->default_engine_type= ha_checktype(thd,
                                          DB_TYPE_DEFAULT, 0, 0);
        }
      }
    }
    DBUG_PRINT("info", ("db_type = %s create_info->db_type = %s",
             ha_resolve_storage_engine_name(part_info->default_engine_type),
             ha_resolve_storage_engine_name(create_info->db_type)));
    if (part_info->check_partition_info(thd, &engine_type, file,
                                        create_info, FALSE))
      goto err;
    part_info->default_engine_type= engine_type;

    /*
      We reverse the partitioning parser and generate a standard format
      for syntax stored in frm file.
    */
    if (!(part_syntax_buf= generate_partition_syntax(part_info,
                                                     &syntax_len,
                                                     TRUE, TRUE,
                                                     create_info,
                                                     alter_info,
                                                     NULL)))
      goto err;
    part_info->part_info_string= part_syntax_buf;
    part_info->part_info_len= syntax_len;
    if ((!(engine_type->partition_flags &&
           engine_type->partition_flags() & HA_CAN_PARTITION)) ||
        create_info->db_type == partition_hton)
    {
      /*
        The handler assigned to the table cannot handle partitioning.
        Assign the partition handler as the handler of the table.
      */
      DBUG_PRINT("info", ("db_type: %s",
                        ha_resolve_storage_engine_name(create_info->db_type)));
      delete file;
      create_info->db_type= partition_hton;
      if (!(file= get_ha_partition(part_info)))
      {
        DBUG_RETURN(TRUE);
      }
      /*
        If we have default number of partitions or subpartitions we
        might require to set-up the part_info object such that it
        creates a proper .par file. The current part_info object is
        only used to create the frm-file and .par-file.
      */
      if (part_info->use_default_num_partitions &&
          part_info->num_parts &&
          (int)part_info->num_parts !=
          file->get_default_no_partitions(create_info))
      {
        uint i;
        List_iterator<partition_element> part_it(part_info->partitions);
        part_it++;
        DBUG_ASSERT(thd->lex->sql_command != SQLCOM_CREATE_TABLE);
        for (i= 1; i < part_info->partitions.elements; i++)
          (part_it++)->part_state= PART_TO_BE_DROPPED;
      }
      else if (part_info->is_sub_partitioned() &&
               part_info->use_default_num_subpartitions &&
               part_info->num_subparts &&
               (int)part_info->num_subparts !=
                 file->get_default_no_partitions(create_info))
      {
        DBUG_ASSERT(thd->lex->sql_command != SQLCOM_CREATE_TABLE);
        part_info->num_subparts= file->get_default_no_partitions(create_info);
      }
    }
    else if (create_info->db_type != engine_type)
    {
      /*
        We come here when we don't use a partitioned handler.
        Since we use a partitioned table it must be "native partitioned".
        We have switched engine from defaults, most likely only specified
        engines in partition clauses.
      */
      delete file;
      if (!(file= get_new_handler((TABLE_SHARE*) 0, thd->mem_root,
                                  engine_type)))
      {
        mem_alloc_error(sizeof(handler));
        DBUG_RETURN(TRUE);
      }
    }
  }
#endif

  if (mysql_prepare_create_table(thd, create_info, alter_info,
                                 internal_tmp_table,
                                 &db_options, file,
                                 &key_info_buffer, &key_count,
                                 select_field_count))
    goto err;

      /* Check if table exists */
  if (create_info->options & HA_LEX_CREATE_TMP_TABLE)
  {
    path_length= build_tmptable_filename(thd, path, sizeof(path));
    create_info->table_options|=HA_CREATE_DELAY_KEY_WRITE;
  }
  else  
  {
    path_length= build_table_filename(path, sizeof(path) - 1, db, alias, reg_ext,
                                      internal_tmp_table ? FN_IS_TMP : 0);
  }

  /* Check if table already exists */
  if ((create_info->options & HA_LEX_CREATE_TMP_TABLE) &&
      find_temporary_table(thd, db, table_name))
  {
    if (create_info->options & HA_LEX_CREATE_IF_NOT_EXISTS)
      goto warn;
    my_error(ER_TABLE_EXISTS_ERROR, MYF(0), alias);
    goto err;
  }

  /* Give warnings for not supported table options */
#if defined(WITH_ARIA_STORAGE_ENGINE)
  extern handlerton *maria_hton;
  if (file->partition_ht() != maria_hton)
#endif
    if (create_info->transactional)
      push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                          ER_ILLEGAL_HA_CREATE_OPTION,
                          ER(ER_ILLEGAL_HA_CREATE_OPTION),
                          file->engine_name()->str,
                          "TRANSACTIONAL=1");

  if (!internal_tmp_table && !(create_info->options & HA_LEX_CREATE_TMP_TABLE))
  {
    if (check_table_file_presence(NULL, path, db, table_name, table_name,
                                  !(create_info->options &
                                    HA_LEX_CREATE_IF_NOT_EXISTS)))
    {
      if (create_info->options & HA_LEX_CREATE_IF_NOT_EXISTS)
        goto warn;
      goto err;
    }
    /*
      We don't assert here, but check the result, because the table could be
      in the table definition cache and in the same time the .frm could be
      missing from the disk, in case of manual intervention which deletes
      the .frm file. The user has to use FLUSH TABLES; to clear the cache.
      Then she could create the table. This case is pretty obscure and
      therefore we don't introduce a new error message only for it.
    */
    mysql_mutex_lock(&LOCK_open);
    if (get_cached_table_share(db, table_name))
    {
      mysql_mutex_unlock(&LOCK_open);
      my_error(ER_TABLE_EXISTS_ERROR, MYF(0), table_name);
      goto err;
    }
    mysql_mutex_unlock(&LOCK_open);
  }

  /*
    Check that table with given name does not already
    exist in any storage engine. In such a case it should
    be discovered and the error ER_TABLE_EXISTS_ERROR be returned
    unless user specified CREATE TABLE IF EXISTS
    An exclusive metadata lock ensures that no
    one else is attempting to discover the table. Since
    it's not on disk as a frm file, no one could be using it!
  */
  if (!(create_info->options & HA_LEX_CREATE_TMP_TABLE))
  {
    bool create_if_not_exists =
      create_info->options & HA_LEX_CREATE_IF_NOT_EXISTS;
    int retcode = ha_table_exists_in_engine(thd, db, table_name);
    DBUG_PRINT("info", ("exists_in_engine: %u",retcode));
    switch (retcode)
    {
      case HA_ERR_NO_SUCH_TABLE:
        /* Normal case, no table exists. we can go and create it */
        break;
      case HA_ERR_TABLE_EXIST:
        DBUG_PRINT("info", ("Table existed in handler"));

        if (create_if_not_exists)
          goto warn;
        my_error(ER_TABLE_EXISTS_ERROR,MYF(0),table_name);
        goto err;
      default:
        DBUG_PRINT("info", ("error: %u from storage engine", retcode));
        my_error(retcode, MYF(0),table_name);
        goto err;
    }
  }

  thd_proc_info(thd, "creating table");

#ifdef HAVE_READLINK
  {
    size_t dirlen;
    char   dirpath[FN_REFLEN];

    /*
      data_file_name and index_file_name include the table name without
      extension. Mostly this does not refer to an existing file. When
      comparing data_file_name or index_file_name against the data
      directory, we try to resolve all symbolic links. On some systems,
      we use realpath(3) for the resolution. This returns ENOENT if the
      resolved path does not refer to an existing file. my_realpath()
      does then copy the requested path verbatim, without symlink
      resolution. Thereafter the comparison can fail even if the
      requested path is within the data directory. E.g. if symlinks to
      another file system are used. To make realpath(3) return the
      resolved path, we strip the table name and compare the directory
      path only. If the directory doesn't exist either, table creation
      will fail anyway.
    */
    if (create_info->data_file_name)
    {
      dirname_part(dirpath, create_info->data_file_name, &dirlen);
      if (test_if_data_home_dir(dirpath))
      {
        my_error(ER_WRONG_ARGUMENTS, MYF(0), "DATA DIRECTORY");
        goto err;
      }
    }
    if (create_info->index_file_name)
    {
      dirname_part(dirpath, create_info->index_file_name, &dirlen);
      if (test_if_data_home_dir(dirpath))
      {
        my_error(ER_WRONG_ARGUMENTS, MYF(0), "INDEX DIRECTORY");
        goto err;
      }
    }
  }

#ifdef WITH_PARTITION_STORAGE_ENGINE
  if (check_partition_dirs(thd->lex->part_info))
  {
    goto err;
  }
#endif /* WITH_PARTITION_STORAGE_ENGINE */

  if (!my_use_symdir || (thd->variables.sql_mode & MODE_NO_DIR_IN_CREATE))
#endif /* HAVE_READLINK */
  {
    if (create_info->data_file_name)
      push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                          WARN_OPTION_IGNORED, ER(WARN_OPTION_IGNORED),
                          "DATA DIRECTORY");
    if (create_info->index_file_name)
      push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                          WARN_OPTION_IGNORED, ER(WARN_OPTION_IGNORED),
                          "INDEX DIRECTORY");
    create_info->data_file_name= create_info->index_file_name= 0;
  }
  create_info->table_options=db_options;

  path[path_length - reg_ext_length]= '\0'; // Remove .frm extension
  if (rea_create_table(thd, path, db, table_name,
                       create_info, alter_info->create_list,
                       key_count, key_info_buffer, file))
    goto err;

  if (create_info->options & HA_LEX_CREATE_TMP_TABLE)
  {
    /*
      Open a table (skipping table cache) and add it into
      THD::temporary_tables list.
    */

    TABLE *table= open_table_uncached(thd, path, db, table_name, TRUE);

    if (!table)
    {
      (void) rm_temporary_table(create_info->db_type, path);
      goto err;
    }

    if (is_trans != NULL)
      *is_trans= table->file->has_transactions();

    thd->thread_specific_used= TRUE;
  }
#ifdef WITH_PARTITION_STORAGE_ENGINE
  else if (part_info && create_info->frm_only)
  {
    /*
      For partitioned tables we can't find some problems with table
      until table is opened. Therefore in order to disallow creation
      of corrupted tables we have to try to open table as the part
      of its creation process.
      In cases when both .FRM and SE part of table are created table
      is implicitly open in ha_create_table() call.
      In cases when we create .FRM without SE part we have to open
      table explicitly.
    */
    if (check_if_created_table_can_be_opened(thd, path, db, table_name,
                                             create_info, file))
    {
      char frm_name[FN_REFLEN];
      strxmov(frm_name, path, reg_ext, NullS);
      (void) mysql_file_delete(key_file_frm, frm_name, MYF(0));
      goto err;
    }
  }
#endif

  error= FALSE;
err:
  thd_proc_info(thd, "After create");
  delete file;
  DBUG_RETURN(error);

warn:
  error= FALSE;
  push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
                      ER_TABLE_EXISTS_ERROR, ER(ER_TABLE_EXISTS_ERROR),
                      alias);
  goto err;
}


/**
  Implementation of SQLCOM_CREATE_TABLE.

  Take the metadata locks (including a shared lock on the affected
  schema) and create the table. Is written to be called from
  mysql_execute_command(), to which it delegates the common parts
  with other commands (i.e. implicit commit before and after,
  close of thread tables.
*/

bool mysql_create_table(THD *thd, TABLE_LIST *create_table,
                        HA_CREATE_INFO *create_info,
                        Alter_info *alter_info)
{
  bool result;
  bool is_trans= FALSE;
  DBUG_ENTER("mysql_create_table");

  /*
    Open or obtain an exclusive metadata lock on table being created.
  */
  if (open_and_lock_tables(thd, thd->lex->query_tables, FALSE, 0))
  {
    /* is_error() may be 0 if table existed and we generated a warning */
    result= thd->is_error();
    goto end;
  }

  /* Got lock. */
  DEBUG_SYNC(thd, "locked_table_name");

  result= mysql_create_table_no_lock(thd, create_table->db,
                                     create_table->table_name, create_info,
                                     alter_info, FALSE, 0, &is_trans);

  /*
    Don't write statement if:
    - Table creation has failed
    - Row-based logging is used and we are creating a temporary table
    Otherwise, the statement shall be binlogged.
  */
  if (!result &&
      (!thd->is_current_stmt_binlog_format_row() ||
       (thd->is_current_stmt_binlog_format_row() &&
        !(create_info->options & HA_LEX_CREATE_TMP_TABLE))))
    result= write_bin_log(thd, TRUE, thd->query(), thd->query_length(), is_trans);

end:
  DBUG_RETURN(result);
}


/*
** Give the key name after the first field with an optional '_#' after
**/

static bool
check_if_keyname_exists(const char *name, KEY *start, KEY *end)
{
  for (KEY *key=start ; key != end ; key++)
    if (!my_strcasecmp(system_charset_info,name,key->name))
      return 1;
  return 0;
}


static char *
make_unique_key_name(const char *field_name,KEY *start,KEY *end)
{
  char buff[MAX_FIELD_NAME],*buff_end;

  if (!check_if_keyname_exists(field_name,start,end) &&
      my_strcasecmp(system_charset_info,field_name,primary_key_name))
    return (char*) field_name;			// Use fieldname
  buff_end=strmake(buff,field_name, sizeof(buff)-4);

  /*
    Only 3 chars + '\0' left, so need to limit to 2 digit
    This is ok as we can't have more than 100 keys anyway
  */
  for (uint i=2 ; i< 100; i++)
  {
    *buff_end= '_';
    int10_to_str(i, buff_end+1, 10);
    if (!check_if_keyname_exists(buff,start,end))
      return sql_strdup(buff);
  }
  return (char*) "not_specified";		// Should never happen
}


/****************************************************************************
** Alter a table definition
****************************************************************************/


/*
  Rename a table.

  SYNOPSIS
    mysql_rename_table()
      base                      The handlerton handle.
      old_db                    The old database name.
      old_name                  The old table name.
      new_db                    The new database name.
      new_name                  The new table name.
      flags                     flags for build_table_filename().
                                FN_FROM_IS_TMP old_name is temporary.
                                FN_TO_IS_TMP   new_name is temporary.
                                NO_FRM_RENAME  Don't rename the FRM file
                                but only the table in the storage engine.
                                NO_FK_CHECKS   Don't check FK constraints
                                during rename.

  RETURN
    FALSE   OK
    TRUE    Error
*/

bool
mysql_rename_table(handlerton *base, const char *old_db,
                   const char *old_name, const char *new_db,
                   const char *new_name, uint flags)
{
  THD *thd= current_thd;
  char from[FN_REFLEN + 1], to[FN_REFLEN + 1],
    lc_from[FN_REFLEN + 1], lc_to[FN_REFLEN + 1];
  char *from_base= from, *to_base= to;
  char tmp_name[SAFE_NAME_LEN+1];
  handler *file;
  int error=0;
  ulonglong save_bits= thd->variables.option_bits;
  DBUG_ENTER("mysql_rename_table");
  DBUG_PRINT("enter", ("old: '%s'.'%s'  new: '%s'.'%s'",
                       old_db, old_name, new_db, new_name));
  
  // Temporarily disable foreign key checks
  if (flags & NO_FK_CHECKS) 
    thd->variables.option_bits|= OPTION_NO_FOREIGN_KEY_CHECKS;

  file= (base == NULL ? 0 :
         get_new_handler((TABLE_SHARE*) 0, thd->mem_root, base));

  build_table_filename(from, sizeof(from) - 1, old_db, old_name, "",
                       flags & FN_FROM_IS_TMP);
  build_table_filename(to, sizeof(to) - 1, new_db, new_name, "",
                       flags & FN_TO_IS_TMP);

  /*
    If lower_case_table_names == 2 (case-preserving but case-insensitive
    file system) and the storage is not HA_FILE_BASED, we need to provide
    a lowercase file name, but we leave the .frm in mixed case.
   */
  if (lower_case_table_names == 2 && file &&
      !(file->ha_table_flags() & HA_FILE_BASED))
  {
    strmov(tmp_name, old_name);
    my_casedn_str(files_charset_info, tmp_name);
    build_table_filename(lc_from, sizeof(lc_from) - 1, old_db, tmp_name, "",
                         flags & FN_FROM_IS_TMP);
    from_base= lc_from;

    strmov(tmp_name, new_name);
    my_casedn_str(files_charset_info, tmp_name);
    build_table_filename(lc_to, sizeof(lc_to) - 1, new_db, tmp_name, "",
                         flags & FN_TO_IS_TMP);
    to_base= lc_to;
  }

  if (!file || !(error=file->ha_rename_table(from_base, to_base)))
  {
    if (!(flags & NO_FRM_RENAME) && rename_file_ext(from,to,reg_ext))
    {
      error=my_errno;
      /* Restore old file name */
      if (file)
        file->ha_rename_table(to_base, from_base);
    }
  }
  delete file;
  if (error == HA_ERR_WRONG_COMMAND)
    my_error(ER_NOT_SUPPORTED_YET, MYF(0), "ALTER TABLE");
  else if (error)
    my_error(ER_ERROR_ON_RENAME, MYF(0), from, to, error);
  else if (!(flags & FN_IS_TMP))
    mysql_audit_rename_table(thd, old_db, old_name, new_db, new_name);
  
  // Restore options bits to the original value
  thd->variables.option_bits= save_bits;

  DBUG_RETURN(error != 0);
}


/*
  Create a table identical to the specified table

  SYNOPSIS
    mysql_create_like_table()
    thd		Thread object
    table       Table list element for target table
    src_table   Table list element for source table
    create_info Create info

  RETURN VALUES
    FALSE OK
    TRUE  error
*/

bool mysql_create_like_table(THD* thd, TABLE_LIST* table, TABLE_LIST* src_table,
                             HA_CREATE_INFO *create_info)
{
  HA_CREATE_INFO local_create_info;
  Alter_info local_alter_info;
  bool res= TRUE;
  bool is_trans= FALSE;
  uint not_used;
  DBUG_ENTER("mysql_create_like_table");


  /*
    We the open source table to get its description in HA_CREATE_INFO
    and Alter_info objects. This also acquires a shared metadata lock
    on this table which ensures that no concurrent DDL operation will
    mess with it.
    Also in case when we create non-temporary table open_tables()
    call obtains an exclusive metadata lock on target table ensuring
    that we can safely perform table creation.
    Thus by holding both these locks we ensure that our statement is
    properly isolated from all concurrent operations which matter.
  */
  if (open_tables(thd, &thd->lex->query_tables, &not_used, 0))
  {
    res= thd->is_error();
    goto err;
  }
  src_table->table->use_all_columns();

  DEBUG_SYNC(thd, "create_table_like_after_open");

  /* Fill HA_CREATE_INFO and Alter_info with description of source table. */
  bzero((char*) &local_create_info, sizeof(local_create_info));
  local_create_info.db_type= src_table->table->s->db_type();
  local_create_info.row_type= src_table->table->s->row_type;
  if (mysql_prepare_alter_table(thd, src_table->table, &local_create_info,
                                &local_alter_info))
    goto err;
#ifdef WITH_PARTITION_STORAGE_ENGINE
  /* Partition info is not handled by mysql_prepare_alter_table() call. */
  if (src_table->table->part_info)
    thd->work_part_info= src_table->table->part_info->get_clone();
#endif

  /*
    Adjust description of source table before using it for creation of
    target table.

    Similarly to SHOW CREATE TABLE we ignore MAX_ROWS attribute of
    temporary table which represents I_S table.
  */
  if (src_table->schema_table)
    local_create_info.max_rows= 0;
  /* Set IF NOT EXISTS option as in the CREATE TABLE LIKE statement. */
  local_create_info.options|= create_info->options&HA_LEX_CREATE_IF_NOT_EXISTS;
  /* Replace type of source table with one specified in the statement. */
  local_create_info.options&= ~HA_LEX_CREATE_TMP_TABLE;
  local_create_info.options|= create_info->options & HA_LEX_CREATE_TMP_TABLE;
  /* Reset auto-increment counter for the new table. */
  local_create_info.auto_increment_value= 0;
  /*
    Do not inherit values of DATA and INDEX DIRECTORY options from
    the original table. This is documented behavior.
  */
  local_create_info.data_file_name= local_create_info.index_file_name= NULL;

  if ((res= mysql_create_table_no_lock(thd, table->db, table->table_name,
                                       &local_create_info, &local_alter_info,
                                       FALSE, 0, &is_trans)))
    goto err;

  /*
    Ensure that we have an exclusive lock on target table if we are creating
    non-temporary table.
  */
  DBUG_ASSERT((create_info->options & HA_LEX_CREATE_TMP_TABLE) ||
              thd->mdl_context.is_lock_owner(MDL_key::TABLE, table->db,
                                             table->table_name,
                                             MDL_EXCLUSIVE));

  DEBUG_SYNC(thd, "create_table_like_before_binlog");

  /*
    We have to write the query before we unlock the tables.
  */
  if (thd->is_current_stmt_binlog_disabled())
    goto err;

  if (thd->is_current_stmt_binlog_format_row())
  {
    /*
       Since temporary tables are not replicated under row-based
       replication, CREATE TABLE ... LIKE ... needs special
       treatement.  We have four cases to consider, according to the
       following decision table:

           ==== ========= ========= ==============================
           Case    Target    Source Write to binary log
           ==== ========= ========= ==============================
           1       normal    normal Original statement
           2       normal temporary Generated statement
           3    temporary    normal Nothing
           4    temporary temporary Nothing
           ==== ========= ========= ==============================
    */
    if (!(create_info->options & HA_LEX_CREATE_TMP_TABLE))
    {
      if (src_table->table->s->tmp_table)               // Case 2
      {
        char buf[2048];
        String query(buf, sizeof(buf), system_charset_info);
        query.length(0);  // Have to zero it since constructor doesn't
        Open_table_context ot_ctx(thd, MYSQL_OPEN_REOPEN);

        /*
          The condition avoids a crash as described in BUG#48506. Other
          binlogging problems related to CREATE TABLE IF NOT EXISTS LIKE
          when the existing object is a view will be solved by BUG 47442.
        */
        if (!table->view)
        {
          /*
            Here we open the destination table, on which we already have
            exclusive metadata lock. This is needed for store_create_info()
            to work. The table will be closed by close_thread_table() at
            the end of this branch.
          */
          if (open_table(thd, table, thd->mem_root, &ot_ctx))
            goto err;

          /*
            After opening a MERGE table add the children to the query list of
            tables, so that children tables info can be used on "CREATE TABLE"
            statement generation by the binary log.
            Note that placeholders don't have the handler open.
          */
          if (table->table->file->extra(HA_EXTRA_ADD_CHILDREN_LIST))
            goto err;

          /*
            As the reference table is temporary and may not exist on slave, we must
            force the ENGINE to be present into CREATE TABLE.
          */
          create_info->used_fields|= HA_CREATE_USED_ENGINE;

          int result __attribute__((unused))=
            store_create_info(thd, table, &query,
                              create_info, TRUE /* show_database */);

          DBUG_ASSERT(result == 0); // store_create_info() always return 0
          if (write_bin_log(thd, TRUE, query.ptr(), query.length()))
            goto err;

          DBUG_ASSERT(thd->open_tables == table->table);
          /*
            When opening the table, we ignored the locked tables
            (MYSQL_OPEN_GET_NEW_TABLE). Now we can close the table without
            risking to close some locked table.
          */
          close_thread_table(thd, &thd->open_tables);
        }
      }
      else                                      // Case 1
        if (write_bin_log(thd, TRUE, thd->query(), thd->query_length()))
          goto err;
    }
    /*
      Case 3 and 4 does nothing under RBR
    */
  }
  else if (write_bin_log(thd, TRUE, thd->query(), thd->query_length(), is_trans))
    goto err;

err:
  DBUG_RETURN(res);
}


/* table_list should contain just one table */
static int
mysql_discard_or_import_tablespace(THD *thd,
                                   TABLE_LIST *table_list,
                                   enum tablespace_op_type tablespace_op)
{
  TABLE *table;
  my_bool discard;
  int error;
  DBUG_ENTER("mysql_discard_or_import_tablespace");

  /*
    Note that DISCARD/IMPORT TABLESPACE always is the only operation in an
    ALTER TABLE
  */

  thd_proc_info(thd, "discard_or_import_tablespace");

  discard= test(tablespace_op == DISCARD_TABLESPACE);

 /*
   We set this flag so that ha_innobase::open and ::external_lock() do
   not complain when we lock the table
 */
  thd->tablespace_op= TRUE;
  table_list->mdl_request.set_type(MDL_SHARED_WRITE);
  if (!(table=open_ltable(thd, table_list, TL_WRITE, 0)))
  {
    thd->tablespace_op=FALSE;
    DBUG_RETURN(-1);
  }

  error= table->file->ha_discard_or_import_tablespace(discard);

  thd_proc_info(thd, "end");

  if (error)
    goto err;

  /*
    The 0 in the call below means 'not in a transaction', which means
    immediate invalidation; that is probably what we wish here
  */
  query_cache_invalidate3(thd, table_list, 0);

  /* The ALTER TABLE is always in its own transaction */
  error= trans_commit_stmt(thd);
  if (trans_commit_implicit(thd))
    error=1;
  if (error)
    goto err;
  error= write_bin_log(thd, FALSE, thd->query(), thd->query_length());

err:
  thd->tablespace_op=FALSE;

  if (error == 0)
  {
    my_ok(thd);
    DBUG_RETURN(0);
  }

  table->file->print_error(error, MYF(0));

  DBUG_RETURN(-1);
}

/**
  @brief Check if both DROP and CREATE are present for an index in ALTER TABLE
 
  @details Checks if any index is being modified (present as both DROP INDEX 
    and ADD INDEX) in the current ALTER TABLE statement. Needed for disabling 
    in-place ALTER TABLE.
  
  @param table       The table being altered
  @param alter_info  The ALTER TABLE structure
  @return presence of index being altered  
  @retval FALSE  No such index
  @retval TRUE   Have at least 1 index modified
*/

static bool
is_index_maintenance_unique (TABLE *table, Alter_info *alter_info)
{
  List_iterator<Key> key_it(alter_info->key_list);
  List_iterator<Alter_drop> drop_it(alter_info->drop_list);
  Key *key;

  while ((key= key_it++))
  {
    if (key->name.str)
    {
      Alter_drop *drop;

      drop_it.rewind();
      while ((drop= drop_it++))
      {
        if (drop->type == Alter_drop::KEY &&
            !my_strcasecmp(system_charset_info, key->name.str, drop->name))
          return TRUE;
      }
    }
  }
  return FALSE;
}


/*
  SYNOPSIS
    mysql_compare_tables()
      table                     The original table.
      alter_info                Alter options, fields and keys for the new
                                table.
      create_info               Create options for the new table.
      order_num                 Number of order list elements.
      need_copy_table     OUT   Result of the comparison. Undefined if error.
                                Otherwise is one of:
                                ALTER_TABLE_METADATA_ONLY  No copy needed
                                ALTER_TABLE_DATA_CHANGED   Data changes,
                                                           copy needed
                                ALTER_TABLE_INDEX_CHANGED  Index changes,
                                                           copy might be needed
      key_info_buffer     OUT   An array of KEY structs for new indexes
      index_drop_buffer   OUT   An array of offsets into table->key_info.
      index_drop_count    OUT   The number of elements in the array.
      index_add_buffer    OUT   An array of offsets into key_info_buffer.
      index_add_count     OUT   The number of elements in the array.
      candidate_key_count OUT   The number of candidate keys in original table.

  DESCRIPTION
    'table' (first argument) contains information of the original
    table, which includes all corresponding parts that the new
    table has in arguments create_list, key_list and create_info.

    By comparing the changes between the original and new table
    we can determine how much it has changed after ALTER TABLE
    and whether we need to make a copy of the table, or just change
    the .frm file.

    If there are no data changes, but index changes, 'index_drop_buffer'
    and/or 'index_add_buffer' are populated with offsets into
    table->key_info or key_info_buffer respectively for the indexes
    that need to be dropped and/or (re-)created.

  RETURN VALUES
    TRUE   The tables are not compatible; We have to do a full alter table
    FALSE  The tables are compatible; We only have to modify the .frm
*/

bool
mysql_compare_tables(TABLE *table,
                     Alter_info *alter_info,
                     HA_CREATE_INFO *create_info,
                     uint order_num,
                     enum_alter_table_change_level *need_copy_table,
                     KEY **key_info_buffer,
                     uint **index_drop_buffer, uint *index_drop_count,
                     uint **index_add_buffer, uint *index_add_count,
                     uint *candidate_key_count)
{
  Field **f_ptr, *field;
  uint changes= 0, tmp;
  uint key_count;
  List_iterator_fast<Create_field> new_field_it, tmp_new_field_it;
  Create_field *new_field, *tmp_new_field;
  KEY_PART_INFO *key_part;
  KEY_PART_INFO *end;
  THD *thd= table->in_use;
  uint i;
  /*
    Remember if the new definition has new VARCHAR column;
    create_info->varchar will be reset in mysql_prepare_create_table.
  */
  bool varchar= create_info->varchar;
  bool not_nullable= true;
  DBUG_ENTER("mysql_compare_tables");

  /*
    Create a copy of alter_info.
    To compare the new and old table definitions, we need to "prepare"
    the new definition - transform it from parser output to a format
    that describes the final table layout (all column defaults are
    initialized, duplicate columns are removed). This is done by
    mysql_prepare_create_table.  Unfortunately,
    mysql_prepare_create_table performs its transformations
    "in-place", that is, modifies the argument.  Since we would
    like to keep mysql_compare_tables() idempotent (not altering any
    of the arguments) we create a copy of alter_info here and
    pass it to mysql_prepare_create_table, then use the result
    to evaluate possibility of in-place ALTER TABLE, and then
    destroy the copy.
  */
  Alter_info tmp_alter_info(*alter_info, thd->mem_root);
  uint db_options= 0; /* not used */

  /* Set default value for return value (to ensure it's always set) */
  *need_copy_table= ALTER_TABLE_DATA_CHANGED;

  /* Create the prepared information. */
  if (mysql_prepare_create_table(thd, create_info,
                                 &tmp_alter_info,
                                 (table->s->tmp_table != NO_TMP_TABLE),
                                 &db_options,
                                 table->file, key_info_buffer,
                                 &key_count, 0))
    DBUG_RETURN(1);
  /* Allocate result buffers. */
  if (! (*index_drop_buffer=
         (uint*) thd->alloc(sizeof(uint) * table->s->keys)) ||
      ! (*index_add_buffer=
         (uint*) thd->alloc(sizeof(uint) * tmp_alter_info.key_list.elements)))
    DBUG_RETURN(1);
  
  /*
    Some very basic checks. If number of fields changes, or the
    handler, we need to run full ALTER TABLE. In the future
    new fields can be added and old dropped without copy, but
    not yet.

    Test also that engine was not given during ALTER TABLE, or
    we are force to run regular alter table (copy).
    E.g. ALTER TABLE tbl_name ENGINE=MyISAM.

    For the following ones we also want to run regular alter table:
    ALTER TABLE tbl_name ORDER BY ..
    ALTER TABLE tbl_name CONVERT TO CHARACTER SET ..

    At the moment we can't handle altering temporary tables without a copy.
    We also test if OPTIMIZE TABLE was given and was mapped to alter table.
    In that case we always do full copy.

    There was a bug prior to mysql-4.0.25. Number of null fields was
    calculated incorrectly. As a result frm and data files gets out of
    sync after in-place alter table. There is no way to determine by which
    mysql version (in 4.0 and 4.1 branches) table was created, thus we
    disable in-place alter table for all tables created by mysql versions
    prior to 5.0 branch.
    See BUG#6236.
  */
  if (table->s->fields != alter_info->create_list.elements ||
      table->s->db_type() != create_info->db_type ||
      table->s->tmp_table ||
      create_info->used_fields & HA_CREATE_USED_ENGINE ||
      create_info->used_fields & HA_CREATE_USED_CHARSET ||
      create_info->used_fields & HA_CREATE_USED_DEFAULT_CHARSET ||
      (table->s->row_type != create_info->row_type) ||
      create_info->used_fields & HA_CREATE_USED_PAGE_CHECKSUM ||
      create_info->used_fields & HA_CREATE_USED_TRANSACTIONAL ||
      create_info->used_fields & HA_CREATE_USED_PACK_KEYS ||
      create_info->used_fields & HA_CREATE_USED_MAX_ROWS ||
      (alter_info->flags & (ALTER_RECREATE | ALTER_FOREIGN_KEY)) ||
      order_num ||
      !table->s->mysql_version ||
      (table->s->frm_version < FRM_VER_TRUE_VARCHAR && varchar))
  {
    DBUG_PRINT("info", ("Basic checks -> ALTER_TABLE_DATA_CHANGED"));
    DBUG_RETURN(0);
  }

  if ((create_info->fields_option_struct= (ha_field_option_struct**)
         thd->calloc(sizeof(void*) * table->s->fields)) == NULL ||
      (create_info->indexes_option_struct= (ha_index_option_struct**)
         thd->calloc(sizeof(void*) * table->s->keys)) == NULL)
    DBUG_RETURN(1);

  /*
    Use transformed info to evaluate possibility of in-place ALTER TABLE
    but use the preserved field to persist modifications.
  */
  new_field_it.init(alter_info->create_list);
  tmp_new_field_it.init(tmp_alter_info.create_list);

  /*
    Go through fields and check if the original ones are compatible
    with new table.
  */
  for (i= 0, f_ptr= table->field, new_field= new_field_it++,
       tmp_new_field= tmp_new_field_it++;
       (field= *f_ptr);
       i++, f_ptr++, new_field= new_field_it++,
       tmp_new_field= tmp_new_field_it++)
  {
    DBUG_ASSERT(i < table->s->fields);
    create_info->fields_option_struct[i]= tmp_new_field->option_struct;

    /* reset common markers of how field changed */
    field->flags&= ~(FIELD_IS_RENAMED | FIELD_IN_ADD_INDEX);

    /* Make sure we have at least the default charset in use. */
    if (!new_field->charset)
      new_field->charset= create_info->default_table_charset;

    /* Check that NULL behavior is same for old and new fields */
    if ((tmp_new_field->flags & NOT_NULL_FLAG) !=
	(uint) (field->flags & NOT_NULL_FLAG))
    {
      DBUG_PRINT("info", ("NULL behaviour difference in field '%s' -> "
                          "ALTER_TABLE_DATA_CHANGED", new_field->field_name));
      DBUG_RETURN(0);
    }

    /*
      Check if the altered column is computed and either
      is stored or is used in the partitioning expression.
      TODO: Mark such a column with an alter flag only if
      the defining expression has changed.
    */
    if (field->vcol_info && 
        (field->stored_in_db || field->vcol_info->is_in_partitioning_expr()))
    {
      *need_copy_table= ALTER_TABLE_DATA_CHANGED;
      DBUG_RETURN(0);
    }

    /* Don't pack rows in old tables if the user has requested this. */
      if (create_info->row_type == ROW_TYPE_DYNAMIC ||
          (tmp_new_field->flags & BLOB_FLAG) ||
          (tmp_new_field->sql_type == MYSQL_TYPE_VARCHAR &&
           create_info->row_type != ROW_TYPE_FIXED))
        create_info->table_options|= HA_OPTION_PACK_RECORD;

    /* Check if field was renamed */
    if (my_strcasecmp(system_charset_info,
		      field->field_name,
		      tmp_new_field->field_name))
      field->flags|= FIELD_IS_RENAMED;      

    /* Evaluate changes bitmap and send to check_if_incompatible_data() */
    if (!(tmp= field->is_equal(tmp_new_field)))
    {
      DBUG_PRINT("info", ("!field_is_equal('%s') -> ALTER_TABLE_DATA_CHANGED",
                          new_field->field_name));
      DBUG_RETURN(0);
    }
    changes|= tmp;
  }

  /*
    Go through keys and check if the original ones are compatible
    with new table.
  */
  KEY *table_key;
  KEY *table_key_end= table->key_info + table->s->keys;
  KEY *new_key;
  KEY *new_key_end= *key_info_buffer + key_count;

  DBUG_PRINT("info", ("index count old: %d  new: %d",
                      table->s->keys, key_count));
  /*
    Step through all keys of the old table and search matching new keys.
  */
  *index_drop_count= 0;
  *index_add_count= 0;
  *candidate_key_count= 0;
  for (table_key= table->key_info; table_key < table_key_end; table_key++)
  {
    KEY_PART_INFO *table_part;
    KEY_PART_INFO *table_part_end= table_key->key_part + table_key->key_parts;
    KEY_PART_INFO *new_part;

   /*
      Check if key is a candidate key, i.e. a unique index with no index
      fields nullable, then key is either already primary key or could
      be promoted to primary key if the original primary key is dropped.
      Count all candidate keys.
    */
    not_nullable= true;
    for (table_part= table_key->key_part;
         table_part < table_part_end;
         table_part++)
    {
      not_nullable= not_nullable && (! table_part->field->maybe_null());
    }
    if ((table_key->flags & HA_NOSAME) && not_nullable)
      (*candidate_key_count)++;

    /* Search a new key with the same name. */
    for (new_key= *key_info_buffer; new_key < new_key_end; new_key++)
    {
      if (! strcmp(table_key->name, new_key->name))
        break;
    }
    if (new_key >= new_key_end)
    {
      /* Key not found. Add the offset of the key to the drop buffer. */
      (*index_drop_buffer)[(*index_drop_count)++]= table_key - table->key_info;
      DBUG_PRINT("info", ("index dropped: '%s'", table_key->name));
      continue;
    }

    /* Check that the key types are compatible between old and new tables. */
    if ((table_key->algorithm != new_key->algorithm) ||
	((table_key->flags & HA_KEYFLAG_MASK) !=
         (new_key->flags & HA_KEYFLAG_MASK)) ||
        (table_key->key_parts != new_key->key_parts))
      goto index_changed;

    /*
      Check that the key parts remain compatible between the old and
      new tables.
    */
    for (table_part= table_key->key_part, new_part= new_key->key_part;
         table_part < table_part_end;
         table_part++, new_part++)
    {
      /*
	Key definition has changed if we are using a different field or
	if the used key part length is different. We know that the fields
        did not change. Comparing field numbers is sufficient.
      */
      if ((table_part->length != new_part->length) ||
          (table_part->fieldnr - 1 != new_part->fieldnr))
	goto index_changed;
    }
    continue;

  index_changed:
    /* Key modified. Add the offset of the key to both buffers. */
    (*index_drop_buffer)[(*index_drop_count)++]= table_key - table->key_info;
    (*index_add_buffer)[(*index_add_count)++]= new_key - *key_info_buffer;
    key_part= new_key->key_part;
    end= key_part + new_key->key_parts;
    for(; key_part != end; key_part++)
    {
      // Mark field to be part of new key 
      field= table->field[key_part->fieldnr];
      field->flags|= FIELD_IN_ADD_INDEX;
    }
    DBUG_PRINT("info", ("index changed: '%s'", table_key->name));
  }
  /*end of for (; table_key < table_key_end;) */

  /*
    Step through all keys of the new table and find matching old keys.
  */
  for (new_key= *key_info_buffer; new_key < new_key_end; new_key++)
  {
    /* Search an old key with the same name. */
    for (i= 0, table_key= table->key_info;
         table_key < table_key_end;
         i++, table_key++)
    {
      if (! strcmp(table_key->name, new_key->name))
        break;
    }
    if (table_key >= table_key_end)
    {
      /* Key not found. Add the offset of the key to the add buffer. */
      (*index_add_buffer)[(*index_add_count)++]= new_key - *key_info_buffer;
      key_part= new_key->key_part;
      end= key_part + new_key->key_parts;
      for(; key_part != end; key_part++)
      {
        // Mark field to be part of new key 
        field= table->field[key_part->fieldnr];
        field->flags|= FIELD_IN_ADD_INDEX;
      }
      DBUG_PRINT("info", ("index added: '%s'", new_key->name));
    }
    else
    {
      DBUG_ASSERT(i < table->s->keys);
      create_info->indexes_option_struct[i]= new_key->option_struct;
    }
  }

  /* Check if changes are compatible with current handler without a copy */
  if (table->file->check_if_incompatible_data(create_info, changes))
  {
    DBUG_PRINT("info", ("check_if_incompatible_data() -> "
                        "ALTER_TABLE_DATA_CHANGED"));
    DBUG_RETURN(0);
  }

  if (*index_drop_count || *index_add_count)
  {
    DBUG_PRINT("info", ("Index dropped=%u added=%u -> "
                        "ALTER_TABLE_INDEX_CHANGED",
                        *index_drop_count, *index_add_count));
    *need_copy_table= ALTER_TABLE_INDEX_CHANGED;
    DBUG_RETURN(0);
  }

  DBUG_PRINT("info", (" -> ALTER_TABLE_METADATA_ONLY"));
  *need_copy_table= ALTER_TABLE_METADATA_ONLY; // Tables are compatible
  DBUG_RETURN(0);
}


/*
  Manages enabling/disabling of indexes for ALTER TABLE

  SYNOPSIS
    alter_table_manage_keys()
      table                  Target table
      indexes_were_disabled  Whether the indexes of the from table
                             were disabled
      keys_onoff             ENABLE | DISABLE | LEAVE_AS_IS

  RETURN VALUES
    FALSE  OK
    TRUE   Error
*/

static
bool alter_table_manage_keys(TABLE *table, int indexes_were_disabled,
                             enum enum_enable_or_disable keys_onoff)
{
  int error= 0;
  DBUG_ENTER("alter_table_manage_keys");
  DBUG_PRINT("enter", ("table=%p were_disabled=%d on_off=%d",
             table, indexes_were_disabled, keys_onoff));

  switch (keys_onoff) {
  case ENABLE:
    error= table->file->ha_enable_indexes(HA_KEY_SWITCH_NONUNIQ_SAVE);
    break;
  case LEAVE_AS_IS:
    if (!indexes_were_disabled)
      break;
    /* fall-through */
  case DISABLE:
    error= table->file->ha_disable_indexes(HA_KEY_SWITCH_NONUNIQ_SAVE);
  }

  if (error == HA_ERR_WRONG_COMMAND)
  {
    push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
                        ER_ILLEGAL_HA, ER(ER_ILLEGAL_HA),
                        table->s->table_name.str);
    error= 0;
  } else if (error)
    table->file->print_error(error, MYF(0));

  DBUG_RETURN(error);
}

/**
  maximum possible length for certain blob types.

  @param[in]      type        Blob type (e.g. MYSQL_TYPE_TINY_BLOB)

  @return
    length
*/

static uint
blob_length_by_type(enum_field_types type)
{
  switch (type)
  {
  case MYSQL_TYPE_TINY_BLOB:
    return 255;
  case MYSQL_TYPE_BLOB:
    return 65535;
  case MYSQL_TYPE_MEDIUM_BLOB:
    return 16777215;
  case MYSQL_TYPE_LONG_BLOB:
    return 4294967295U;
  default:
    DBUG_ASSERT(0); // we should never go here
    return 0;
  }
}


/**
  Prepare column and key definitions for CREATE TABLE in ALTER TABLE.

  This function transforms parse output of ALTER TABLE - lists of
  columns and keys to add, drop or modify into, essentially,
  CREATE TABLE definition - a list of columns and keys of the new
  table. While doing so, it also performs some (bug not all)
  semantic checks.

  This function is invoked when we know that we're going to
  perform ALTER TABLE via a temporary table -- i.e. in-place ALTER TABLE
  is not possible, perhaps because the ALTER statement contains
  instructions that require change in table data, not only in
  table definition or indexes.

  @param[in,out]  thd         thread handle. Used as a memory pool
                              and source of environment information.
  @param[in]      table       the source table, open and locked
                              Used as an interface to the storage engine
                              to acquire additional information about
                              the original table.
  @param[in,out]  create_info A blob with CREATE/ALTER TABLE
                              parameters
  @param[in,out]  alter_info  Another blob with ALTER/CREATE parameters.
                              Originally create_info was used only in
                              CREATE TABLE and alter_info only in ALTER TABLE.
                              But since ALTER might end-up doing CREATE,
                              this distinction is gone and we just carry
                              around two structures.

  @return
    Fills various create_info members based on information retrieved
    from the storage engine.
    Sets create_info->varchar if the table has a VARCHAR column.
    Prepares alter_info->create_list and alter_info->key_list with
    columns and keys of the new table.

  @retval TRUE   error, out of memory or a semantical error in ALTER
                 TABLE instructions
  @retval FALSE  success
*/

bool
mysql_prepare_alter_table(THD *thd, TABLE *table,
                          HA_CREATE_INFO *create_info,
                          Alter_info *alter_info)
{
  /* New column definitions are added here */
  List<Create_field> new_create_list;
  /* New key definitions are added here */
  List<Key> new_key_list;
  List_iterator<Alter_drop> drop_it(alter_info->drop_list);
  List_iterator<Create_field> def_it(alter_info->create_list);
  List_iterator<Alter_column> alter_it(alter_info->alter_list);
  List_iterator<Key> key_it(alter_info->key_list);
  List_iterator<Create_field> find_it(new_create_list);
  List_iterator<Create_field> field_it(new_create_list);
  List<Key_part_spec> key_parts;
  uint db_create_options= (table->s->db_create_options
                           & ~(HA_OPTION_PACK_RECORD));
  uint used_fields= create_info->used_fields;
  KEY *key_info=table->key_info;
  bool rc= TRUE;
  Create_field *def;
  Field **f_ptr,*field;
  DBUG_ENTER("mysql_prepare_alter_table");

  create_info->varchar= FALSE;
  /* Let new create options override the old ones */
  if (!(used_fields & HA_CREATE_USED_MIN_ROWS))
    create_info->min_rows= table->s->min_rows;
  if (!(used_fields & HA_CREATE_USED_MAX_ROWS))
    create_info->max_rows= table->s->max_rows;
  if (!(used_fields & HA_CREATE_USED_AVG_ROW_LENGTH))
    create_info->avg_row_length= table->s->avg_row_length;
  if (!(used_fields & HA_CREATE_USED_DEFAULT_CHARSET))
    create_info->default_table_charset= table->s->table_charset;
  if (!(used_fields & HA_CREATE_USED_AUTO) && table->found_next_number_field)
  {
    /* Table has an autoincrement, copy value to new table */
    table->file->info(HA_STATUS_AUTO);
    create_info->auto_increment_value= table->file->stats.auto_increment_value;
  }
  if (!(used_fields & HA_CREATE_USED_KEY_BLOCK_SIZE))
    create_info->key_block_size= table->s->key_block_size;
  if (!(used_fields & HA_CREATE_USED_TRANSACTIONAL))
    create_info->transactional= table->s->transactional;

  /* Creation of federated table with LIKE clause needs connection string */
  if (!(used_fields & HA_CREATE_USED_CONNECTION))
    create_info->connect_string= table->s->connect_string;

  restore_record(table, s->default_values);     // Empty record for DEFAULT

  create_info->option_list= merge_engine_table_options(table->s->option_list,
                                        create_info->option_list, thd->mem_root);
  /*
    First collect all fields from table which isn't in drop_list
  */
  for (f_ptr=table->field ; (field= *f_ptr) ; f_ptr++)
  {
    Alter_drop *drop;
    if (field->type() == MYSQL_TYPE_VARCHAR)
      create_info->varchar= TRUE;
    /* Check if field should be dropped */
    drop_it.rewind();
    while ((drop=drop_it++))
    {
      if (drop->type == Alter_drop::COLUMN &&
	  !my_strcasecmp(system_charset_info,field->field_name, drop->name))
      {
	/* Reset auto_increment value if it was dropped */
	if (MTYP_TYPENR(field->unireg_check) == Field::NEXT_NUMBER &&
	    !(used_fields & HA_CREATE_USED_AUTO))
	{
	  create_info->auto_increment_value=0;
	  create_info->used_fields|=HA_CREATE_USED_AUTO;
	}
	break;
      }
    }
    if (drop)
    {
      drop_it.remove();
      /*
        ALTER TABLE DROP COLUMN always changes table data even in cases
        when new version of the table has the same structure as the old
        one.
      */
      alter_info->change_level= ALTER_TABLE_DATA_CHANGED;
      continue;
    }
    /* Check if field is changed */
    def_it.rewind();
    while ((def=def_it++))
    {
      if (def->change &&
	  !my_strcasecmp(system_charset_info,field->field_name, def->change))
	break;
    }
    if (def)
    {						// Field is changed
      def->field=field;
      if (field->stored_in_db != def->stored_in_db)
      {
        my_error(ER_UNSUPPORTED_ACTION_ON_VIRTUAL_COLUMN, MYF(0));
        goto err;
      }
      if (!def->after)
      {
	new_create_list.push_back(def);
	def_it.remove();
      }
    }
    else
    {
      /*
        This field was not dropped and not changed, add it to the list
        for the new table.
      */
      def= new Create_field(field, field);
      new_create_list.push_back(def);
      alter_it.rewind();			// Change default if ALTER
      Alter_column *alter;
      while ((alter=alter_it++))
      {
	if (!my_strcasecmp(system_charset_info,field->field_name, alter->name))
	  break;
      }
      if (alter)
      {
	if (def->sql_type == MYSQL_TYPE_BLOB)
	{
	  my_error(ER_BLOB_CANT_HAVE_DEFAULT, MYF(0), def->change);
          goto err;
	}
	if ((def->def=alter->def))              // Use new default
          def->flags&= ~NO_DEFAULT_VALUE_FLAG;
        else
          def->flags|= NO_DEFAULT_VALUE_FLAG;
	alter_it.remove();
      }
    }
  }
  def_it.rewind();
  while ((def=def_it++))			// Add new columns
  {
    if (def->change && ! def->field)
    {
      /*
        Check if there is modify for newly added field.
      */
      Create_field *find;
      find_it.rewind();
      while((find=find_it++))
      {
        if (!my_strcasecmp(system_charset_info,find->field_name, def->field_name))
          break;
      }

      if (find && !find->field)
	find_it.remove();
      else
      {
        my_error(ER_BAD_FIELD_ERROR, MYF(0), def->change,
                 table->s->table_name.str);
        goto err;
      }
    }
    /*
      Check that the DATE/DATETIME not null field we are going to add is
      either has a default value or the '0000-00-00' is allowed by the
      set sql mode.
      If the '0000-00-00' value isn't allowed then raise the error_if_not_empty
      flag to allow ALTER TABLE only if the table to be altered is empty.
    */
    if ((def->sql_type == MYSQL_TYPE_DATE ||
         def->sql_type == MYSQL_TYPE_NEWDATE ||
         def->sql_type == MYSQL_TYPE_DATETIME) &&
         !alter_info->datetime_field &&
         !(~def->flags & (NO_DEFAULT_VALUE_FLAG | NOT_NULL_FLAG)) &&
         thd->variables.sql_mode & MODE_NO_ZERO_DATE)
    {
        alter_info->datetime_field= def;
        alter_info->error_if_not_empty= TRUE;
    }
    if (!def->after)
      new_create_list.push_back(def);
    else if (def->after == first_keyword)
    {
      new_create_list.push_front(def);
      /*
        Re-ordering columns in table can't be done using in-place algorithm
        as it always changes table data.
      */
      alter_info->change_level= ALTER_TABLE_DATA_CHANGED;
    }
    else
    {
      Create_field *find;
      find_it.rewind();
      while ((find=find_it++))			// Add new columns
      {
	if (!my_strcasecmp(system_charset_info,def->after, find->field_name))
	  break;
      }
      if (!find)
      {
	my_error(ER_BAD_FIELD_ERROR, MYF(0), def->after,
                 table->s->table_name.str);
        goto err;
      }
      find_it.after(def);			// Put element after this
      /*
        Re-ordering columns in table can't be done using in-place algorithm
        as it always changes table data.
      */
      alter_info->change_level= ALTER_TABLE_DATA_CHANGED;
    }
    /*
      Check if there is alter for newly added field.
    */
    alter_it.rewind();
    Alter_column *alter;
    while ((alter=alter_it++))
    {
      if (!my_strcasecmp(system_charset_info,def->field_name, alter->name))
        break;
    }
    if (alter)
    {
      if (def->sql_type == MYSQL_TYPE_BLOB)
      {
        my_error(ER_BLOB_CANT_HAVE_DEFAULT, MYF(0), def->change);
        goto err;
      }
      if ((def->def=alter->def))              // Use new default
        def->flags&= ~NO_DEFAULT_VALUE_FLAG;
      else
        def->flags|= NO_DEFAULT_VALUE_FLAG;
      alter_it.remove();
    }
  }
  if (alter_info->alter_list.elements)
  {
    my_error(ER_BAD_FIELD_ERROR, MYF(0),
             alter_info->alter_list.head()->name, table->s->table_name.str);
    goto err;
  }
  if (!new_create_list.elements)
  {
    my_message(ER_CANT_REMOVE_ALL_FIELDS, ER(ER_CANT_REMOVE_ALL_FIELDS),
               MYF(0));
    goto err;
  }

  /*
    Collect all keys which isn't in drop list. Add only those
    for which some fields exists.
  */

  for (uint i=0 ; i < table->s->keys ; i++,key_info++)
  {
    char *key_name= key_info->name;
    Alter_drop *drop;
    drop_it.rewind();
    while ((drop=drop_it++))
    {
      if (drop->type == Alter_drop::KEY &&
	  !my_strcasecmp(system_charset_info,key_name, drop->name))
	break;
    }
    if (drop)
    {
      drop_it.remove();
      continue;
    }

    KEY_PART_INFO *key_part= key_info->key_part;
    key_parts.empty();
    for (uint j=0 ; j < key_info->key_parts ; j++,key_part++)
    {
      if (!key_part->field)
	continue;				// Wrong field (from UNIREG)
      const char *key_part_name=key_part->field->field_name;
      Create_field *cfield;
      uint key_part_length;

      field_it.rewind();
      while ((cfield=field_it++))
      {
	if (cfield->change)
	{
	  if (!my_strcasecmp(system_charset_info, key_part_name,
			     cfield->change))
	    break;
	}
	else if (!my_strcasecmp(system_charset_info,
				key_part_name, cfield->field_name))
	  break;
      }
      if (!cfield)
	continue;				// Field is removed
      key_part_length= key_part->length;
      if (cfield->field)			// Not new field
      {
        /*
          If the field can't have only a part used in a key according to its
          new type, or should not be used partially according to its
          previous type, or the field length is less than the key part
          length, unset the key part length.

          We also unset the key part length if it is the same as the
          old field's length, so the whole new field will be used.

          BLOBs may have cfield->length == 0, which is why we test it before
          checking whether cfield->length < key_part_length (in chars).
          
          In case of TEXTs we check the data type maximum length *in bytes*
          to key part length measured *in characters* (i.e. key_part_length
          devided to mbmaxlen). This is because it's OK to have:
          CREATE TABLE t1 (a tinytext, key(a(254)) character set utf8);
          In case of this example:
          - data type maximum length is 255.
          - key_part_length is 1016 (=254*4, where 4 is mbmaxlen)
         */
        if (!Field::type_can_have_key_part(cfield->field->type()) ||
            !Field::type_can_have_key_part(cfield->sql_type) ||
            /* spatial keys can't have sub-key length */
            (key_info->flags & HA_SPATIAL) ||
            (cfield->field->field_length == key_part_length &&
             !f_is_blob(key_part->key_type)) ||
            (cfield->length && (((cfield->sql_type >= MYSQL_TYPE_TINY_BLOB &&
                                  cfield->sql_type <= MYSQL_TYPE_BLOB) ? 
                                blob_length_by_type(cfield->sql_type) :
                                cfield->length) <
	     key_part_length / key_part->field->charset()->mbmaxlen)))
	  key_part_length= 0;			// Use whole field
      }
      key_part_length /= key_part->field->charset()->mbmaxlen;
      key_parts.push_back(new Key_part_spec(cfield->field_name,
                                            strlen(cfield->field_name),
					    key_part_length));
    }
    if (key_parts.elements)
    {
      KEY_CREATE_INFO key_create_info;
      Key *key;
      enum Key::Keytype key_type;
      bzero((char*) &key_create_info, sizeof(key_create_info));

      key_create_info.algorithm= key_info->algorithm;
      if (key_info->flags & HA_USES_BLOCK_SIZE)
        key_create_info.block_size= key_info->block_size;
      if (key_info->flags & HA_USES_PARSER)
        key_create_info.parser_name= *plugin_name(key_info->parser);
      if (key_info->flags & HA_USES_COMMENT)
        key_create_info.comment= key_info->comment;

      if (key_info->flags & HA_SPATIAL)
        key_type= Key::SPATIAL;
      else if (key_info->flags & HA_NOSAME)
      {
        if (! my_strcasecmp(system_charset_info, key_name, primary_key_name))
          key_type= Key::PRIMARY;
        else
          key_type= Key::UNIQUE;
      }
      else if (key_info->flags & HA_FULLTEXT)
        key_type= Key::FULLTEXT;
      else
        key_type= Key::MULTIPLE;

      key= new Key(key_type, key_name, strlen(key_name),
                   &key_create_info,
                   test(key_info->flags & HA_GENERATED_KEY),
                   key_parts, key_info->option_list);
      new_key_list.push_back(key);
    }
  }
  {
    Key *key;
    while ((key=key_it++))			// Add new keys
    {
      if (key->type == Key::FOREIGN_KEY &&
          ((Foreign_key *)key)->validate(new_create_list))
        goto err;
      if (key->type != Key::FOREIGN_KEY)
        new_key_list.push_back(key);
      if (key->name.str &&
	  !my_strcasecmp(system_charset_info, key->name.str, primary_key_name))
      {
	my_error(ER_WRONG_NAME_FOR_INDEX, MYF(0), key->name.str);
        goto err;
      }
    }
  }

  if (alter_info->drop_list.elements)
  {
    my_error(ER_CANT_DROP_FIELD_OR_KEY, MYF(0),
             alter_info->drop_list.head()->name);
    goto err;
  }
  if (alter_info->alter_list.elements)
  {
    my_error(ER_CANT_DROP_FIELD_OR_KEY, MYF(0),
             alter_info->alter_list.head()->name);
    goto err;
  }

  if (!create_info->comment.str)
  {
    create_info->comment.str= table->s->comment.str;
    create_info->comment.length= table->s->comment.length;
  }

  table->file->update_create_info(create_info);
  if ((create_info->table_options &
       (HA_OPTION_PACK_KEYS | HA_OPTION_NO_PACK_KEYS)) ||
      (used_fields & HA_CREATE_USED_PACK_KEYS))
    db_create_options&= ~(HA_OPTION_PACK_KEYS | HA_OPTION_NO_PACK_KEYS);
  if (create_info->table_options &
      (HA_OPTION_CHECKSUM | HA_OPTION_NO_CHECKSUM))
    db_create_options&= ~(HA_OPTION_CHECKSUM | HA_OPTION_NO_CHECKSUM);
  if (create_info->table_options &
      (HA_OPTION_DELAY_KEY_WRITE | HA_OPTION_NO_DELAY_KEY_WRITE))
    db_create_options&= ~(HA_OPTION_DELAY_KEY_WRITE |
			  HA_OPTION_NO_DELAY_KEY_WRITE);
  create_info->table_options|= db_create_options;

  if (table->s->tmp_table)
    create_info->options|=HA_LEX_CREATE_TMP_TABLE;

  rc= FALSE;
  alter_info->create_list.swap(new_create_list);
  alter_info->key_list.swap(new_key_list);
err:
  DBUG_RETURN(rc);
}


/*
  Alter table

  SYNOPSIS
    mysql_alter_table()
      thd              Thread handle
      new_db           If there is a RENAME clause
      new_name         If there is a RENAME clause
      create_info      Information from the parsing phase about new
                       table properties.
      table_list       The table to change.
      alter_info       Lists of fields, keys to be changed, added
                       or dropped.
      order_num        How many ORDER BY fields has been specified.
      order            List of fields to ORDER BY.
      ignore           Whether we have ALTER IGNORE TABLE
      require_online   Give an error if we can't do operation online

  DESCRIPTION
    This is a veery long function and is everything but the kitchen sink :)
    It is used to alter a table and not only by ALTER TABLE but also
    CREATE|DROP INDEX are mapped on this function.

    When the ALTER TABLE statement just does a RENAME or ENABLE|DISABLE KEYS,
    or both, then this function short cuts its operation by renaming
    the table and/or enabling/disabling the keys. In this case, the FRM is
    not changed, directly by mysql_alter_table. However, if there is a
    RENAME + change of a field, or an index, the short cut is not used.
    See how `create_list` is used to generate the new FRM regarding the
    structure of the fields. The same is done for the indices of the table.

    Important is the fact, that this function tries to do as little work as
    possible, by finding out whether a intermediate table is needed to copy
    data into and when finishing the altering to use it as the original table.
    For this reason the function mysql_compare_tables() is called, which decides
    based on all kind of data how similar are the new and the original
    tables.

  RETURN VALUES
    FALSE  OK
    TRUE   Error
*/

bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
                       HA_CREATE_INFO *create_info,
                       TABLE_LIST *table_list,
                       Alter_info *alter_info,
                       uint order_num, ORDER *order, bool ignore,
                       bool require_online)
{
  TABLE *table, *new_table= 0;
  MDL_ticket *mdl_ticket;
  MDL_request target_mdl_request;
  int error= 0;
  char tmp_name[80],old_name[32],new_name_buff[FN_REFLEN + 1];
  char old_name_buff[FN_REFLEN + 1];
  char new_alias_buff[FN_REFLEN], *table_name, *db, *new_alias, *alias;
  char index_file[FN_REFLEN], data_file[FN_REFLEN];
  char path[FN_REFLEN + 1];
  char reg_path[FN_REFLEN+1];
  ha_rows copied,deleted;
  handlerton *old_db_type, *new_db_type, *save_old_db_type;
  enum_alter_table_change_level need_copy_table= ALTER_TABLE_METADATA_ONLY;
#ifdef WITH_PARTITION_STORAGE_ENGINE
  TABLE *table_for_fast_alter_partition= NULL;
  bool partition_changed= FALSE;
#endif
  bool need_lock_for_indexes __attribute__((unused)) = TRUE;
  KEY  *key_info_buffer;
  uint index_drop_count= 0;
  uint *index_drop_buffer= NULL;
  uint index_add_count= 0;
  handler_add_index *add= NULL;
  bool pending_inplace_add_index= false;
  uint *index_add_buffer= NULL;
  uint candidate_key_count= 0;
  bool no_pk;
  ulong explicit_used_fields= 0;
  enum ha_extra_function extra_func= thd->locked_tables_mode
                                       ? HA_EXTRA_NOT_USED
                                       : HA_EXTRA_FORCE_REOPEN;
  DBUG_ENTER("mysql_alter_table");

  /*
    Check if we attempt to alter mysql.slow_log or
    mysql.general_log table and return an error if
    it is the case.
    TODO: this design is obsolete and will be removed.
  */
  if (table_list && table_list->db && table_list->table_name)
  {
    int table_kind= 0;

    table_kind= check_if_log_table(table_list->db_length, table_list->db,
                                   table_list->table_name_length,
                                   table_list->table_name, 0);

    if (table_kind)
    {
      /* Disable alter of enabled log tables */
      if (logger.is_log_table_enabled(table_kind))
      {
        my_error(ER_BAD_LOG_STATEMENT, MYF(0), "ALTER");
        DBUG_RETURN(TRUE);
      }

      /* Disable alter of log tables to unsupported engine */
      if ((create_info->used_fields & HA_CREATE_USED_ENGINE) &&
          (!create_info->db_type || /* unknown engine */
           !(create_info->db_type->flags & HTON_SUPPORT_LOG_TABLES)))
      {
        my_error(ER_UNSUPORTED_LOG_ENGINE, MYF(0));
        DBUG_RETURN(TRUE);
      }

#ifdef WITH_PARTITION_STORAGE_ENGINE
      if (alter_info->flags & ALTER_PARTITION)
      {
        my_error(ER_WRONG_USAGE, MYF(0), "PARTITION", "log table");
        DBUG_RETURN(TRUE);
      }
#endif
    }
  }

  /*
    Assign variables table_name, new_name, db, new_db, path, reg_path
    to simplify further comparisions: we want to see if it's a RENAME
    later just by comparing the pointers, avoiding the need for strcmp.
  */
  thd_proc_info(thd, "init");
  table_name=table_list->table_name;
  alias= (lower_case_table_names == 2) ? table_list->alias : table_name;
  db=table_list->db;
  if (!new_db || !my_strcasecmp(table_alias_charset, new_db, db))
    new_db= db;
  build_table_filename(reg_path, sizeof(reg_path) - 1, db, table_name, reg_ext, 0);
  build_table_filename(path, sizeof(path) - 1, db, table_name, "", 0);

  mysql_ha_rm_tables(thd, table_list);

  /* DISCARD/IMPORT TABLESPACE is always alone in an ALTER TABLE */
  if (alter_info->tablespace_op != NO_TABLESPACE_OP)
  {
    mysql_audit_alter_table(thd, table_list);

    /* Conditionally writes to binlog. */
    bool ret= mysql_discard_or_import_tablespace(thd,table_list,
                                                 alter_info->tablespace_op);
    DBUG_RETURN(ret);
  }

  /*
    Code below can handle only base tables so ensure that we won't open a view.
    Note that RENAME TABLE the only ALTER clause which is supported for views
    has been already processed.
  */
  table_list->required_type= FRMTYPE_TABLE;

  Alter_table_prelocking_strategy alter_prelocking_strategy(alter_info);

  DEBUG_SYNC(thd, "alter_table_before_open_tables");
  error= open_and_lock_tables(thd, table_list, FALSE, 0,
                              &alter_prelocking_strategy);

  if (error)
  {
    DBUG_RETURN(TRUE);
  }

  table= table_list->table;
  table->use_all_columns();
  mdl_ticket= table->mdl_ticket;

  /*
    Prohibit changing of the UNION list of a non-temporary MERGE table
    under LOCK tables. It would be quite difficult to reuse a shrinked
    set of tables from the old table or to open a new TABLE object for
    an extended list and verify that they belong to locked tables.
  */
  if ((thd->locked_tables_mode == LTM_LOCK_TABLES ||
       thd->locked_tables_mode == LTM_PRELOCKED_UNDER_LOCK_TABLES) &&
      (create_info->used_fields & HA_CREATE_USED_UNION) &&
      (table->s->tmp_table == NO_TMP_TABLE))
  {
    my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
    DBUG_RETURN(TRUE);
  }

  /* Check that we are not trying to rename to an existing table */
  if (new_name)
  {
    DBUG_PRINT("info", ("new_db.new_name: '%s'.'%s'", new_db, new_name));
    strmov(new_name_buff,new_name);
    strmov(new_alias= new_alias_buff, new_name);
    if (lower_case_table_names)
    {
      if (lower_case_table_names != 2)
      {
	my_casedn_str(files_charset_info, new_name_buff);
	new_alias= new_name;			// Create lower case table name
      }
      my_casedn_str(files_charset_info, new_name);
    }
    if (new_db == db &&
	!my_strcasecmp(table_alias_charset, new_name_buff, table_name))
    {
      /*
	Source and destination table names are equal: make later check
	easier.
      */
      new_alias= new_name= table_name;
    }
    else
    {
      if (table->s->tmp_table != NO_TMP_TABLE)
      {
	if (find_temporary_table(thd,new_db,new_name_buff))
	{
	  my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_name_buff);
	  DBUG_RETURN(TRUE);
	}
      }
      else
      {
        MDL_request_list mdl_requests;
        MDL_request target_db_mdl_request;

        target_mdl_request.init(MDL_key::TABLE, new_db, new_name,
                                MDL_EXCLUSIVE, MDL_TRANSACTION);
        mdl_requests.push_front(&target_mdl_request);

        /*
          If we are moving the table to a different database, we also
          need IX lock on the database name so that the target database
          is protected by MDL while the table is moved.
        */
        if (new_db != db)
        {
          target_db_mdl_request.init(MDL_key::SCHEMA, new_db, "",
                                     MDL_INTENTION_EXCLUSIVE,
                                     MDL_TRANSACTION);
          mdl_requests.push_front(&target_db_mdl_request);
        }

        /*
          Global intention exclusive lock must have been already acquired when
          table to be altered was open, so there is no need to do it here.
        */
        DBUG_ASSERT(thd->mdl_context.is_lock_owner(MDL_key::GLOBAL,
                                                   "", "",
                                                   MDL_INTENTION_EXCLUSIVE));

        if (thd->mdl_context.acquire_locks(&mdl_requests,
                                           thd->variables.lock_wait_timeout))
          DBUG_RETURN(TRUE);

        DEBUG_SYNC(thd, "locked_table_name");
        /*
          Table maybe does not exist, but we got an exclusive lock
          on the name, now we can safely try to find out for sure.
        */
        build_table_filename(new_name_buff, sizeof(new_name_buff) - 1,
                             new_db, new_name_buff, reg_ext, 0);
        build_table_filename(old_name_buff, sizeof(old_name_buff) - 1,
                             db, table_name, reg_ext, 0);
        if (check_table_file_presence(old_name_buff, new_name_buff, new_db,
                                      new_name, new_alias, TRUE))
	{
	  /* Table will be closed in do_command() */
          goto err;
	}
      }
    }
  }
  else
  {
    new_alias= (lower_case_table_names == 2) ? alias : table_name;
    new_name= table_name;
  }

  old_db_type= table->s->db_type();
  if (!create_info->db_type)
  {
#ifdef WITH_PARTITION_STORAGE_ENGINE
    if (table->part_info &&
        create_info->used_fields & HA_CREATE_USED_ENGINE)
    {
      /*
        This case happens when the user specified
        ENGINE = x where x is a non-existing storage engine
        We set create_info->db_type to default_engine_type
        to ensure we don't change underlying engine type
        due to a erroneously given engine name.
      */
      create_info->db_type= table->part_info->default_engine_type;
    }
    else
#endif
      create_info->db_type= old_db_type;
  }

  if (check_engine(thd, new_db, new_name, create_info))
    goto err;
  new_db_type= create_info->db_type;

  if ((new_db_type != old_db_type ||
       alter_info->flags & ALTER_PARTITION) &&
      !table->file->can_switch_engines())
  {
    my_error(ER_ROW_IS_REFERENCED, MYF(0));
    goto err;
  }

  /*
   If foreign key is added then check permission to access parent table.

   In function "check_fk_parent_table_access", create_info->db_type is used
   to identify whether engine supports FK constraint or not. Since
   create_info->db_type is set here, check to parent table access is delayed
   till this point for the alter operation.
  */
  if ((alter_info->flags & ALTER_FOREIGN_KEY) &&
      check_fk_parent_table_access(thd, create_info, alter_info, new_db))
    goto err;

  /*
    If this is an ALTER TABLE and no explicit row type specified reuse
    the table's row type.
    Note: this is the same as if the row type was specified explicitly and
    we must thus set HA_CREATE_USED_ROW_FORMAT!
  */
  if (create_info->row_type == ROW_TYPE_NOT_USED)
  {
    /* ALTER TABLE without explicit row type */
    create_info->row_type= table->s->row_type;
    /*
      We have to mark the row type as used, as otherwise the engine may
      change the row format in update_create_info().
    */
    create_info->used_fields|= HA_CREATE_USED_ROW_FORMAT;
    explicit_used_fields|= HA_CREATE_USED_ROW_FORMAT;
  }

  DBUG_PRINT("info", ("old type: %s  new type: %s",
             ha_resolve_storage_engine_name(old_db_type),
             ha_resolve_storage_engine_name(new_db_type)));
  if (ha_check_storage_engine_flag(old_db_type, HTON_ALTER_NOT_SUPPORTED) ||
      ha_check_storage_engine_flag(new_db_type, HTON_ALTER_NOT_SUPPORTED))
  {
    DBUG_PRINT("info", ("doesn't support alter"));
    my_error(ER_ILLEGAL_HA, MYF(0), table_name);
    goto err;
  }

  if (table->s->tmp_table == NO_TMP_TABLE)
    mysql_audit_alter_table(thd, table_list);
  
  thd_proc_info(thd, "setup");
  if (!(alter_info->flags & ~(ALTER_RENAME | ALTER_KEYS_ONOFF)) &&
      !table->s->tmp_table) // no need to touch frm
  {
    switch (alter_info->keys_onoff) {
    case LEAVE_AS_IS:
      break;
    case ENABLE:
      if (wait_while_table_is_used(thd, table, extra_func,
                                   TDC_RT_REMOVE_NOT_OWN_AND_MARK_NOT_USABLE))
        goto err;
      DEBUG_SYNC(thd,"alter_table_enable_indexes");
      error= table->file->ha_enable_indexes(HA_KEY_SWITCH_NONUNIQ_SAVE);
      table->s->allow_access_to_protected_table();
      break;
    case DISABLE:
      if (wait_while_table_is_used(thd, table, extra_func,
                                   TDC_RT_REMOVE_NOT_OWN_AND_MARK_NOT_USABLE))
        goto err;
      error=table->file->ha_disable_indexes(HA_KEY_SWITCH_NONUNIQ_SAVE);
      table->s->allow_access_to_protected_table();
      break;
    default:
      DBUG_ASSERT(FALSE);
      error= 0;
      break;
    }
    if (error == HA_ERR_WRONG_COMMAND)
    {
      error= 0;
      push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
			  ER_ILLEGAL_HA, ER(ER_ILLEGAL_HA),
			  table->alias.c_ptr());
    }

    if (!error && (new_name != table_name || new_db != db))
    {
      thd_proc_info(thd, "rename");
      /*
        Then do a 'simple' rename of the table. First we need to close all
        instances of 'source' table.
        Note that if wait_while_table_is_used() returns error here (i.e. if
        this thread was killed) then it must be that previous step of
        simple rename did nothing and therefore we can safely return
        without additional clean-up.
      */
      if (wait_while_table_is_used(thd, table, extra_func,
                                   TDC_RT_REMOVE_NOT_OWN_AND_MARK_NOT_USABLE))
        goto err;
      close_all_tables_for_name(thd, table->s, HA_EXTRA_PREPARE_FOR_RENAME);
      /*
        Then, we want check once again that target table does not exist.
        Actually the order of these two steps does not matter since
        earlier we took exclusive metadata lock on the target table, so
        we do them in this particular order only to be consistent with 5.0,
        in which we don't take this lock and where this order really matters.
        TODO: Investigate if we need this access() check at all.
      */
      if (!access(new_name_buff,F_OK))
      {
        my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_name);
        error= -1;
      }
      else
      {
        *fn_ext(new_name)=0;
        if (mysql_rename_table(old_db_type,db,table_name,new_db,new_alias, 0))
          error= -1;
        else if (Table_triggers_list::change_table_name(thd, db,
                                                        alias, table_name,
                                                        new_db, new_alias))
        {
          (void) mysql_rename_table(old_db_type, new_db, new_alias, db,
                                    table_name, NO_FK_CHECKS);
          error= -1;
        }
      }
    }

    if (error == HA_ERR_WRONG_COMMAND)
    {
      error= 0;
      push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
			  ER_ILLEGAL_HA, ER(ER_ILLEGAL_HA),
			  table->alias.c_ptr());
    }

    if (!error)
    {
      error= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
      if (!error)
        my_ok(thd);
    }
    else if (error > 0)
    {
      table->file->print_error(error, MYF(0));
      error= -1;
    }
    table_list->table= NULL;                    // For query cache
    query_cache_invalidate3(thd, table_list, 0);

    if ((thd->locked_tables_mode == LTM_LOCK_TABLES ||
         thd->locked_tables_mode == LTM_PRELOCKED_UNDER_LOCK_TABLES))
    {
      /*
        Under LOCK TABLES we should adjust meta-data locks before finishing
        statement. Otherwise we can rely on them being released
        along with the implicit commit.
      */
      if (new_name != table_name || new_db != db)
        thd->mdl_context.release_all_locks_for_name(mdl_ticket);
      else
        mdl_ticket->downgrade_exclusive_lock(MDL_SHARED_NO_READ_WRITE);
    }
    DBUG_RETURN(error);
  }

  /* We have to do full alter table. */

#ifdef WITH_PARTITION_STORAGE_ENGINE
  if (prep_alter_part_table(thd, table, alter_info, create_info, old_db_type,
                            &partition_changed,
                            db, table_name, path,
                            &table_for_fast_alter_partition))
    goto err;
#endif
  /*
    If the old table had partitions and we are doing ALTER TABLE ...
    engine= <new_engine>, the new table must preserve the original
    partitioning. That means that the new engine is still the
    partitioning engine, not the engine specified in the parser.
    This is discovered  in prep_alter_part_table, which in such case
    updates create_info->db_type.
    Now we need to update the stack copy of create_info->db_type,
    as otherwise we won't be able to correctly move the files of the
    temporary table to the result table files.
  */
  new_db_type= create_info->db_type;

  if (is_index_maintenance_unique (table, alter_info))
    need_copy_table= ALTER_TABLE_DATA_CHANGED;

  if (mysql_prepare_alter_table(thd, table, create_info, alter_info))
    goto err;
  
  /* Remove markers set for update_create_info */
  create_info->used_fields&= ~explicit_used_fields;

  if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
    need_copy_table= alter_info->change_level;

  set_table_default_charset(thd, create_info, db);

  if (thd->variables.old_alter_table
      || (table->s->db_type() != create_info->db_type)
#ifdef WITH_PARTITION_STORAGE_ENGINE
      || partition_changed
#endif
     )
    need_copy_table= ALTER_TABLE_DATA_CHANGED;
  else
  {
    enum_alter_table_change_level need_copy_table_res;
    /* Check how much the tables differ. */
    if (mysql_compare_tables(table, alter_info,
                             create_info, order_num,
                             &need_copy_table_res,
                             &key_info_buffer,
                             &index_drop_buffer, &index_drop_count,
                             &index_add_buffer, &index_add_count,
                             &candidate_key_count))
      goto err;
   
    DBUG_EXECUTE_IF("alter_table_only_metadata_change", {
      if (need_copy_table_res != ALTER_TABLE_METADATA_ONLY)
        goto err; });
    DBUG_EXECUTE_IF("alter_table_only_index_change", {
      if (need_copy_table_res != ALTER_TABLE_INDEX_CHANGED)
        goto err; });
   
    if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
      need_copy_table= need_copy_table_res;
  }

  /*
    If there are index changes only, try to do them in-place. "Index
    changes only" means also that the handler for the table does not
    change. The table is open and locked. The handler can be accessed.
  */
  if (need_copy_table == ALTER_TABLE_INDEX_CHANGED)
  {
    int   pk_changed= 0;
    ulong alter_flags= 0;
    ulong needed_inplace_with_read_flags= 0;
    ulong needed_inplace_flags= 0;
    KEY   *key;
    uint  *idx_p;
    uint  *idx_end_p;

    alter_flags= table->file->alter_table_flags(alter_info->flags);
    DBUG_PRINT("info", ("alter_flags: %lu", alter_flags));
    /* Check dropped indexes. */
    for (idx_p= index_drop_buffer, idx_end_p= idx_p + index_drop_count;
         idx_p < idx_end_p;
         idx_p++)
    {
      key= table->key_info + *idx_p;
      DBUG_PRINT("info", ("index dropped: '%s'", key->name));
      if (key->flags & HA_NOSAME)
      {
        /* 
           Unique key. Check for "PRIMARY". 
           or if dropping last unique key
        */
        if ((uint) (key - table->key_info) == table->s->primary_key)
        {
          DBUG_PRINT("info", ("Dropping primary key"));
          /* Primary key. */
          needed_inplace_with_read_flags|= HA_INPLACE_DROP_PK_INDEX_NO_WRITE;
          needed_inplace_flags|= HA_INPLACE_DROP_PK_INDEX_NO_READ_WRITE;
          pk_changed++;
          candidate_key_count--;
        }
        else
        {
          KEY_PART_INFO *part_end= key->key_part + key->key_parts;
          bool is_candidate_key= true;

          /* Non-primary unique key. */
          needed_inplace_with_read_flags|=
            HA_INPLACE_DROP_UNIQUE_INDEX_NO_WRITE;
          needed_inplace_flags|= HA_INPLACE_DROP_UNIQUE_INDEX_NO_READ_WRITE;

          /*
            Check if all fields in key are declared
            NOT NULL and adjust candidate_key_count
          */
          for (KEY_PART_INFO *key_part= key->key_part;
               key_part < part_end;
               key_part++)
            is_candidate_key=
              (is_candidate_key && 
               (! table->field[key_part->fieldnr-1]->maybe_null()));
          if (is_candidate_key)
            candidate_key_count--;
        }
      }
      else
      {
        /* Non-unique key. */
        needed_inplace_with_read_flags|= HA_INPLACE_DROP_INDEX_NO_WRITE;
        needed_inplace_flags|= HA_INPLACE_DROP_INDEX_NO_READ_WRITE;
      }
    }
    no_pk= ((table->s->primary_key == MAX_KEY) ||
            (needed_inplace_with_read_flags &
             HA_INPLACE_DROP_PK_INDEX_NO_WRITE));
    /* Check added indexes. */
    for (idx_p= index_add_buffer, idx_end_p= idx_p + index_add_count;
         idx_p < idx_end_p;
         idx_p++)
    {
      key= key_info_buffer + *idx_p;
      DBUG_PRINT("info", ("index added: '%s'", key->name));
      if (key->flags & HA_NOSAME)
      {
        /* Unique key */

        KEY_PART_INFO *part_end= key->key_part + key->key_parts;    
        bool is_candidate_key= true;

        /*
          Check if all fields in key are declared
          NOT NULL
         */
        for (KEY_PART_INFO *key_part= key->key_part;
             key_part < part_end;
             key_part++)
          is_candidate_key=
            (is_candidate_key && 
             (! table->field[key_part->fieldnr]->maybe_null()));

        /*
           Check for "PRIMARY"
           or if adding first unique key
           defined on non-nullable fields
        */

        if ((!my_strcasecmp(system_charset_info,
                            key->name, primary_key_name)) ||
            (no_pk && candidate_key_count == 0 && is_candidate_key))
        {
          DBUG_PRINT("info", ("Adding primary key"));
          /* Primary key. */
          needed_inplace_with_read_flags|= HA_INPLACE_ADD_PK_INDEX_NO_WRITE;
          needed_inplace_flags|= HA_INPLACE_ADD_PK_INDEX_NO_READ_WRITE;
          pk_changed++;
          no_pk= false;
        }
        else
        {
          /* Non-primary unique key. */
          needed_inplace_with_read_flags|= HA_INPLACE_ADD_UNIQUE_INDEX_NO_WRITE;
          needed_inplace_flags|= HA_INPLACE_ADD_UNIQUE_INDEX_NO_READ_WRITE;
          if (ignore)
          {
            /*
              If ignore is used, we have to remove all duplicate rows,
              which require a full table copy.
            */
            need_copy_table= ALTER_TABLE_DATA_CHANGED;
            pk_changed= 2;                      // Don't change need_copy_table
            break;
          }
        }
      }
      else
      {
        /* Non-unique key. */
        needed_inplace_with_read_flags|= HA_INPLACE_ADD_INDEX_NO_WRITE;
        needed_inplace_flags|= HA_INPLACE_ADD_INDEX_NO_READ_WRITE;
      }
    }

    if ((candidate_key_count > 0) &&
        (needed_inplace_with_read_flags & HA_INPLACE_DROP_PK_INDEX_NO_WRITE))
    {
      /*
        Dropped primary key when there is some other unique 
        not null key that should be converted to primary key
      */
      needed_inplace_with_read_flags|= HA_INPLACE_ADD_PK_INDEX_NO_WRITE;
      needed_inplace_flags|= HA_INPLACE_ADD_PK_INDEX_NO_READ_WRITE;
      pk_changed= 2;
    }

    DBUG_PRINT("info",
          ("needed_inplace_with_read_flags: 0x%lx, needed_inplace_flags: 0x%lx",
           needed_inplace_with_read_flags, needed_inplace_flags));
    /*
      In-place add/drop index is possible only if
      the primary key is not added and dropped in the same statement.
      Otherwise we have to recreate the table.
      need_copy_table is no-zero at this place.

      Also, in-place is not possible if we add a primary key
      and drop another key in the same statement. If the drop fails,
      we will not be able to revert adding of primary key.
    */
    if ( pk_changed < 2 )
    {
      if ((needed_inplace_with_read_flags & HA_INPLACE_ADD_PK_INDEX_NO_WRITE) &&
          index_drop_count > 0)
      {
        /*
          Do copy, not in-place ALTER.
          Avoid setting ALTER_TABLE_METADATA_ONLY.
        */
      }
      else if ((alter_flags & needed_inplace_with_read_flags) ==
               needed_inplace_with_read_flags)
      {
        /* All required in-place flags to allow concurrent reads are present. */
        need_copy_table= ALTER_TABLE_METADATA_ONLY;
        need_lock_for_indexes= FALSE;
      }
      else if ((alter_flags & needed_inplace_flags) == needed_inplace_flags)
      {
        /* All required in-place flags are present. */
        need_copy_table= ALTER_TABLE_METADATA_ONLY;
      }
    }
    DBUG_PRINT("info", ("need_copy_table: %u  need_lock: %d",
                        need_copy_table, need_lock_for_indexes));
  }

  /*
    better have a negative test here, instead of positive, like
    alter_info->flags & ALTER_ADD_COLUMN|ALTER_ADD_INDEX|...
    so that ALTER TABLE won't break when somebody will add new flag
  */
  if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
    create_info->frm_only= 1;

#ifdef WITH_PARTITION_STORAGE_ENGINE
  if (table_for_fast_alter_partition)
  {
    DBUG_RETURN(fast_alter_partition_table(thd, table, alter_info,
                                           create_info, table_list,
                                           db, table_name,
                                           table_for_fast_alter_partition));
  }
#endif

  my_snprintf(tmp_name, sizeof(tmp_name), "%s-%lx_%lx", tmp_file_prefix,
	      current_pid, thd->thread_id);
  /* Safety fix for innodb */
  if (lower_case_table_names)
    my_casedn_str(files_charset_info, tmp_name);

  /*
    Handling of symlinked tables:
    If no rename:
      Create new data file and index file on the same disk as the
      old data and index files.
      Copy data.
      Rename new data file over old data file and new index file over
      old index file.
      Symlinks are not changed.

   If rename:
      Create new data file and index file on the same disk as the
      old data and index files.  Create also symlinks to point at
      the new tables.
      Copy data.
      At end, rename intermediate tables, and symlinks to intermediate
      table, to final table name.
      Remove old table and old symlinks

    If rename is made to another database:
      Create new tables in new database.
      Copy data.
      Remove old table and symlinks.
  */
  if (!strcmp(db, new_db))		// Ignore symlink if db changed
  {
    if (create_info->index_file_name)
    {
      /* Fix index_file_name to have 'tmp_name' as basename */
      strmov(index_file, tmp_name);
      create_info->index_file_name=fn_same(index_file,
					   create_info->index_file_name,
					   1);
    }
    if (create_info->data_file_name)
    {
      /* Fix data_file_name to have 'tmp_name' as basename */
      strmov(data_file, tmp_name);
      create_info->data_file_name=fn_same(data_file,
					  create_info->data_file_name,
					  1);
    }
  }
  else
    create_info->data_file_name=create_info->index_file_name=0;

  DEBUG_SYNC(thd, "alter_table_before_create_table_no_lock");
  DBUG_EXECUTE_IF("sleep_before_create_table_no_lock",
                  my_sleep(100000););
  /*
    Create a table with a temporary name.
    With create_info->frm_only == 1 this creates a .frm file only and
    we keep the original row format.
    We don't log the statement, it will be logged later.
  */
  if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
  {
    DBUG_ASSERT(create_info->frm_only);
    /* Ensure we keep the original table format */
    create_info->table_options= ((create_info->table_options &
                                  ~HA_OPTION_PACK_RECORD) |
                                 (table->s->db_create_options &
                                  HA_OPTION_PACK_RECORD));
  }
  tmp_disable_binlog(thd);
  create_info->options|=HA_CREATE_TMP_ALTER;
  error= mysql_create_table_no_lock(thd, new_db, tmp_name,
                                    create_info,
                                    alter_info,
                                    1, 0, NULL);
  reenable_binlog(thd);
  if (error)
    goto err;

  /* Open the table if we need to copy the data. */
  DBUG_PRINT("info", ("need_copy_table: %u", need_copy_table));
  if (need_copy_table != ALTER_TABLE_METADATA_ONLY)
  {
    if (table->s->tmp_table)
    {
      Open_table_context ot_ctx(thd, (MYSQL_OPEN_IGNORE_FLUSH |
                                      MYSQL_OPEN_FOR_REPAIR |
                                      MYSQL_LOCK_IGNORE_TIMEOUT));
      TABLE_LIST tbl;
      bzero((void*) &tbl, sizeof(tbl));
      tbl.db= new_db;
      tbl.table_name= tbl.alias= tmp_name;
      /* Table is in thd->temporary_tables */
      (void) open_table(thd, &tbl, thd->mem_root, &ot_ctx);
      new_table= tbl.table;
    }
    else
    {
      char path[FN_REFLEN + 1];
      /* table is a normal table: Create temporary table in same directory */
      build_table_filename(path, sizeof(path) - 1, new_db, tmp_name, "",
                           FN_IS_TMP);
      /* Open our intermediate table. */
      new_table= open_table_uncached(thd, path, new_db, tmp_name, TRUE);
    }
    if (!new_table)
      goto err_new_table_cleanup;
    /*
      Note: In case of MERGE table, we do not attach children. We do not
      copy data for MERGE tables. Only the children have data.
    */
  }

  /* Check if we can do the ALTER TABLE as online */
  if (require_online)
  {
    if (index_add_count || index_drop_count ||
        (new_table &&
         !(new_table->file->ha_table_flags() & HA_NO_COPY_ON_ALTER)))
    {
      my_error(ER_CANT_DO_ONLINE, MYF(0), "ALTER");
      goto err_new_table_cleanup;
    }
  }

  /* Copy the data if necessary. */
  thd->count_cuted_fields= CHECK_FIELD_WARN;	// calc cuted fields
  thd->cuted_fields=0L;
  copied=deleted=0;

  /*
    We do not copy data for MERGE tables. Only the children have data.
    MERGE tables have HA_NO_COPY_ON_ALTER set.
  */
  if (new_table && !(new_table->file->ha_table_flags() & HA_NO_COPY_ON_ALTER))
  {
    /* We don't want update TIMESTAMP fields during ALTER TABLE. */
    new_table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;
    new_table->next_number_field=new_table->found_next_number_field;
    DBUG_EXECUTE_IF("abort_copy_table", {
        my_error(ER_LOCK_WAIT_TIMEOUT, MYF(0));
        goto err_new_table_cleanup;
      });
    error= copy_data_between_tables(thd, table, new_table,
                                    alter_info->create_list, ignore,
                                    order_num, order, &copied, &deleted,
                                    alter_info->keys_onoff,
                                    alter_info->error_if_not_empty);
  }
  else
  {
    /*
      Ensure that we will upgrade the metadata lock if
      handler::enable/disable_indexes() will be called.
    */
    if (alter_info->keys_onoff != LEAVE_AS_IS ||
        table->file->indexes_are_disabled())
      need_lock_for_indexes= true;
    if (!table->s->tmp_table && need_lock_for_indexes &&
        wait_while_table_is_used(thd, table, extra_func,
                                 TDC_RT_REMOVE_NOT_OWN_AND_MARK_NOT_USABLE))
      goto err_new_table_cleanup;
    thd_proc_info(thd, "manage keys");
    DEBUG_SYNC(thd, "alter_table_manage_keys");
    alter_table_manage_keys(table, table->file->indexes_are_disabled(),
                            alter_info->keys_onoff);
    error= trans_commit_stmt(thd);
    if (trans_commit_implicit(thd))
      error= 1;
    /*
      If the table was locked, allow one to still run SHOW commands against it
    */
    if (table->s->protected_against_usage())
      table->s->allow_access_to_protected_table();
  }
  thd->count_cuted_fields= CHECK_FIELD_IGNORE;

  if (error)
    goto err_new_table_cleanup;

  /* If we did not need to copy, we might still need to add/drop indexes. */
  if (! new_table)
  {
    uint          *key_numbers;
    uint          *keyno_p;
    KEY           *key_info;
    KEY           *key;
    uint          *idx_p;
    uint          *idx_end_p;
    KEY_PART_INFO *key_part;
    KEY_PART_INFO *part_end;
    DBUG_PRINT("info", ("No new_table, checking add/drop index"));

    table->file->ha_prepare_for_alter();
    if (index_add_count)
    {
      /* The add_index() method takes an array of KEY structs. */
      key_info= (KEY*) thd->alloc(sizeof(KEY) * index_add_count);
      key= key_info;
      for (idx_p= index_add_buffer, idx_end_p= idx_p + index_add_count;
           idx_p < idx_end_p;
           idx_p++, key++)
      {
        /* Copy the KEY struct. */
        *key= key_info_buffer[*idx_p];
        /* Fix the key parts. */
        part_end= key->key_part + key->key_parts;
        for (key_part= key->key_part; key_part < part_end; key_part++)
          key_part->field= table->field[key_part->fieldnr];
      }
      /* Add the indexes. */
      if ((error= table->file->add_index(table, key_info, index_add_count,
                                         &add)))
      {
        /* Only report error if handler has not already reported an error */
        if (!thd->is_error())
        {
          /*
            HACK HACK HACK
            Prepare the list of keys for an error message.
            It must match what the engine does internally in ::add_index().
            Here we emulate what innobase_create_key_def() does.
            Luckily, in 10.0 this will go away.
          */
          KEY *save_key_info= table->key_info;
          uint add_cnt= index_add_count, old_cnt= table->s->keys;
          KEY *merged= (KEY*)thd->alloc((old_cnt + add_cnt) * sizeof(KEY));
#define is_PK(K) (!my_strcasecmp(system_charset_info, (K)->name, "PRIMARY"))

          if (is_PK(key_info))
          {
            merged[0]= key_info[0];
            if (table->key_info && is_PK(table->key_info))
            {
              old_cnt--;
              table->key_info++;
            }
            memcpy(merged + 1, table->key_info, old_cnt * sizeof(KEY));
            memcpy(merged + old_cnt + 1, key_info + 1, (add_cnt - 1) * sizeof(KEY));
          }
          else
            merged= key_info;

          table->key_info= merged;
          table->file->print_error(error, MYF(0));
          table->key_info= save_key_info;
        }
        goto err_new_table_cleanup;
      }
      pending_inplace_add_index= true;
    }
    /*end of if (index_add_count)*/

    if (index_drop_count)
    {
      /* Currently we must finalize add index if we also drop indexes */
      if (pending_inplace_add_index)
      {
        /* Committing index changes needs exclusive metadata lock. */
        DBUG_ASSERT(thd->mdl_context.is_lock_owner(MDL_key::TABLE,
                                                   table_list->db,
                                                   table_list->table_name,
                                                   MDL_EXCLUSIVE));
        if ((error= table->file->final_add_index(add, true)))
        {
          table->file->print_error(error, MYF(0));
          goto err_new_table_cleanup;
        }
        pending_inplace_add_index= false;
      }
      /* The prepare_drop_index() method takes an array of key numbers. */
      key_numbers= (uint*) thd->alloc(sizeof(uint) * index_drop_count);
      keyno_p= key_numbers;
      /* Get the number of each key. */
      for (idx_p= index_drop_buffer, idx_end_p= idx_p + index_drop_count;
           idx_p < idx_end_p;
           idx_p++, keyno_p++)
        *keyno_p= *idx_p;
      /*
        Tell the handler to prepare for drop indexes.
        This re-numbers the indexes to get rid of gaps.
      */
      error= table->file->prepare_drop_index(table, key_numbers,
                                             index_drop_count);
      if (!error)
      {
        /* Tell the handler to finally drop the indexes. */
        error= table->file->final_drop_index(table);
      }

      if (error)
      {
        table->file->print_error(error, MYF(0));
        if (index_add_count) // Drop any new indexes added.
        {
          /*
            Temporarily set table-key_info to include information about the
            indexes added above that we now need to drop.
          */
          KEY *save_key_info= table->key_info;
          table->key_info= key_info_buffer;
          if ((error= table->file->prepare_drop_index(table, index_add_buffer,
                                                      index_add_count)))
            table->file->print_error(error, MYF(0));
          else if ((error= table->file->final_drop_index(table)))
            table->file->print_error(error, MYF(0));
          table->key_info= save_key_info;
        }

        /*
          Mark this TABLE instance as stale to avoid
          out-of-sync index information.
        */
        table->m_needs_reopen= true;
        goto err_new_table_cleanup;
      }
    }
    /*end of if (index_drop_count)*/

    /*
      The final .frm file is already created as a temporary file
      and will be renamed to the original table name later.
    */

    /* Need to commit before a table is unlocked (NDB requirement). */
    DBUG_PRINT("info", ("Committing before unlocking table"));
    if (trans_commit_stmt(thd) || trans_commit_implicit(thd))
      goto err_new_table_cleanup;
  }
  /*end of if (! new_table) for add/drop index*/

  DBUG_ASSERT(error == 0);

  if (table->s->tmp_table != NO_TMP_TABLE)
  {
    /*
      In-place operations are not supported for temporary tables, so
      we don't have to call final_add_index() in this case. The assert
      verifies that in-place add index has not been done.
    */
    DBUG_ASSERT(!pending_inplace_add_index);
    /* Close lock if this is a transactional table */
    if (thd->lock)
    {
      if (thd->locked_tables_mode != LTM_LOCK_TABLES &&
          thd->locked_tables_mode != LTM_PRELOCKED_UNDER_LOCK_TABLES)
      {
        mysql_unlock_tables(thd, thd->lock);
        thd->lock=0;
      }
      else
      {
        /*
          If LOCK TABLES list is not empty and contains this table,
          unlock the table and remove the table from this list.
        */
        mysql_lock_remove(thd, thd->lock, table);
      }
    }
    /* Remove link to old table and rename the new one */
    close_temporary_table(thd, table, 1, 1);
    /* Should pass the 'new_name' as we store table name in the cache */
    if (rename_temporary_table(thd, new_table, new_db, new_name))
      goto err_new_table_cleanup;
    /* We don't replicate alter table statement on temporary tables */
    if (!thd->is_current_stmt_binlog_format_row() &&
        write_bin_log(thd, TRUE, thd->query(), thd->query_length()))
      DBUG_RETURN(TRUE);
    goto end_temporary;
  }

  /*
    Close the intermediate table that will be the new table, but do
    not delete it! Even altough MERGE tables do not have their children
    attached here it is safe to call close_temporary_table().
  */
  if (new_table)
  {
    close_temporary_table(thd, new_table, 1, 0);
    new_table= 0;
  }
  DEBUG_SYNC(thd, "alter_table_before_rename_result_table");

  /*
    Data is copied. Now we:
    1) Wait until all other threads will stop using old version of table
       by upgrading shared metadata lock to exclusive one.
    2) Close instances of table open by this thread and replace them
       with placeholders to simplify reopen process.
    3) Rename the old table to a temp name, rename the new one to the
       old name.
    4) If we are under LOCK TABLES and don't do ALTER TABLE ... RENAME
       we reopen new version of table.
    5) Write statement to the binary log.
    6) If we are under LOCK TABLES and do ALTER TABLE ... RENAME we
       remove placeholders and release metadata locks.
    7) If we are not not under LOCK TABLES we rely on the caller
      (mysql_execute_command()) to release metadata locks.
  */

  thd_proc_info(thd, "rename result table");
  my_snprintf(old_name, sizeof(old_name), "%s2-%lx-%lx", tmp_file_prefix,
	      current_pid, thd->thread_id);
  if (lower_case_table_names)
    my_casedn_str(files_charset_info, old_name);

  if (wait_while_table_is_used(thd, table, HA_EXTRA_PREPARE_FOR_RENAME,
                               TDC_RT_REMOVE_NOT_OWN_AND_MARK_NOT_USABLE))
  {
    if (pending_inplace_add_index)
    {
      pending_inplace_add_index= false;
      table->file->final_add_index(add, false);
    }
    // Mark this TABLE instance as stale to avoid out-of-sync index information.
    table->m_needs_reopen= true;
    goto err_new_table_cleanup;
  }
  if (pending_inplace_add_index)
  {
    pending_inplace_add_index= false;
    DBUG_EXECUTE_IF("alter_table_rollback_new_index", {
      table->file->final_add_index(add, false);
      my_error(ER_UNKNOWN_ERROR, MYF(0));
      goto err_new_table_cleanup;
    });
    if ((error= table->file->final_add_index(add, true)))
    {
      table->file->print_error(error, MYF(0));
      goto err_new_table_cleanup;
    }
  }

  close_all_tables_for_name(thd, table->s,
                            new_name != table_name || new_db != db ?
                            HA_EXTRA_PREPARE_FOR_RENAME :
                            HA_EXTRA_NOT_USED);

  error=0;
  table_list->table= table= 0;                  /* Safety */
  save_old_db_type= old_db_type;

  /*
    This leads to the storage engine (SE) not being notified for renames in
    mysql_rename_table(), because we just juggle with the FRM and nothing
    more. If we have an intermediate table, then we notify the SE that
    it should become the actual table. Later, we will recycle the old table.
    However, in case of ALTER TABLE RENAME there might be no intermediate
    table. This is when the old and new tables are compatible, according to
    mysql_compare_table(). Then, we need one additional call to
    mysql_rename_table() with flag NO_FRM_RENAME, which does nothing else but
    actual rename in the SE and the FRM is not touched. Note that, if the
    table is renamed and the SE is also changed, then an intermediate table
    is created and the additional call will not take place.
  */
  if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
  {
    DBUG_ASSERT(new_db_type == old_db_type);
    /* This type cannot happen in regular ALTER. */
    new_db_type= old_db_type= NULL;
  }
  if (mysql_rename_table(old_db_type, db, table_name, db, old_name,
                         FN_TO_IS_TMP))
  {
    error=1;
    (void) quick_rm_table(new_db_type, new_db, tmp_name, FN_IS_TMP);
  }
  else if (mysql_rename_table(new_db_type, new_db, tmp_name, new_db,
                              new_alias, FN_FROM_IS_TMP))
  {
    /* Try to get everything back. */
    error= 1;
    (void) quick_rm_table(new_db_type, new_db, tmp_name, FN_IS_TMP);
    (void) mysql_rename_table(old_db_type, db, old_name, db, alias,
                            FN_FROM_IS_TMP | NO_FK_CHECKS);
  }
  else if (new_name != table_name || new_db != db)
  {
    if (need_copy_table == ALTER_TABLE_METADATA_ONLY &&
        mysql_rename_table(save_old_db_type, db, table_name, new_db,
                           new_alias, NO_FRM_RENAME))
    {
      /* Try to get everything back. */
      error= 1;
      (void) quick_rm_table(new_db_type, new_db, new_alias, 0);
      (void) mysql_rename_table(old_db_type, db, old_name, db, alias,
                                FN_FROM_IS_TMP | NO_FK_CHECKS);
    }
    else if (Table_triggers_list::change_table_name(thd, db, alias, 
                                                    table_name, new_db, 
                                                    new_alias))
    {
      /* Try to get everything back. */
      error= 1;
      (void) quick_rm_table(new_db_type, new_db, new_alias, 0);
      (void) mysql_rename_table(old_db_type, db, old_name, db,
                                alias, FN_FROM_IS_TMP | NO_FK_CHECKS);
      /*
        If we were performing "fast"/in-place ALTER TABLE we also need
        to restore old name of table in storage engine as a separate
        step, as the above rename affects .FRM only.
      */
      if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
      {
        (void) mysql_rename_table(save_old_db_type, new_db, new_alias,
                                  db, table_name, 
                                  NO_FRM_RENAME | NO_FK_CHECKS); 
      }
    }
  }

  if (! error)
    (void) quick_rm_table(old_db_type, db, old_name, FN_IS_TMP);

  if (error)
  {
    /* This shouldn't happen. But let us play it safe. */
    goto err_with_mdl;
  }

  if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
  {
    /*
      Now we have to inform handler that new .FRM file is in place.
      To do this we need to obtain a handler object for it.
      NO need to tamper with MERGE tables. The real open is done later.
    */
    Open_table_context ot_ctx(thd, MYSQL_OPEN_REOPEN);
    TABLE_LIST temp_table_list;
    TABLE_LIST *t_table_list;
    if (new_name != table_name || new_db != db)
    {
      temp_table_list.init_one_table(new_db, strlen(new_db),
                                     new_name, strlen(new_name),
                                     new_name, TL_READ_NO_INSERT);
      temp_table_list.mdl_request.ticket= target_mdl_request.ticket;
      t_table_list= &temp_table_list;
    }
    else
    {
      /*
        Under LOCK TABLES, we have a different mdl_lock_ticket
        points to a different instance than the one set initially
        to request the lock.
      */
      table_list->mdl_request.ticket= mdl_ticket;
      t_table_list= table_list;
    }
    if (open_table(thd, t_table_list, thd->mem_root, &ot_ctx))
    {
      goto err_with_mdl;
    }

    /* Tell the handler that a new frm file is in place. */
    error= t_table_list->table->file->ha_create_handler_files(path, NULL,
                                                              CHF_INDEX_FLAG,
                                                              create_info);

    DBUG_ASSERT(thd->open_tables == t_table_list->table);
    close_thread_table(thd, &thd->open_tables);
    t_table_list->table= NULL;

    if (error)
      goto err_with_mdl;
  }
  if (thd->locked_tables_list.reopen_tables(thd))
    goto err_with_mdl;

  thd_proc_info(thd, "end");

  DBUG_EXECUTE_IF("sleep_alter_before_main_binlog", my_sleep(6000000););
  DEBUG_SYNC(thd, "alter_table_before_main_binlog");

  ha_binlog_log_query(thd, create_info->db_type, LOGCOM_ALTER_TABLE,
                      thd->query(), thd->query_length(),
                      db, table_name);

  DBUG_ASSERT(!(mysql_bin_log.is_open() &&
                thd->is_current_stmt_binlog_format_row() &&
                (create_info->options & HA_LEX_CREATE_TMP_TABLE)));
  if (write_bin_log(thd, TRUE, thd->query(), thd->query_length()))
    DBUG_RETURN(TRUE);

  table_list->table=0;				// For query cache
  query_cache_invalidate3(thd, table_list, 0);

  if (thd->locked_tables_mode == LTM_LOCK_TABLES ||
      thd->locked_tables_mode == LTM_PRELOCKED_UNDER_LOCK_TABLES)
  {
    if ((new_name != table_name || new_db != db))
      thd->mdl_context.release_all_locks_for_name(mdl_ticket);
    else
      mdl_ticket->downgrade_exclusive_lock(MDL_SHARED_NO_READ_WRITE);
  }

end_temporary:
  my_snprintf(tmp_name, sizeof(tmp_name), ER(ER_INSERT_INFO),
	      (ulong) (copied + deleted), (ulong) deleted,
	      (ulong) thd->warning_info->statement_warn_count());
  my_ok(thd, copied + deleted, 0L, tmp_name);
  DBUG_RETURN(FALSE);

err_new_table_cleanup:
  if (new_table)
  {
    /* close_temporary_table() frees the new_table pointer. */
    close_temporary_table(thd, new_table, 1, 1);
  }
  else
    (void) quick_rm_table(new_db_type, new_db, tmp_name,
                          create_info->frm_only ? FN_IS_TMP | FRM_ONLY : FN_IS_TMP);

err:
#ifdef WITH_PARTITION_STORAGE_ENGINE
  /* If prep_alter_part_table created an intermediate table, destroy it. */
  if (table_for_fast_alter_partition)
    close_temporary(table_for_fast_alter_partition, 1, 0);
#endif /* WITH_PARTITION_STORAGE_ENGINE */
  /*
    No default value was provided for a DATE/DATETIME field, the
    current sql_mode doesn't allow the '0000-00-00' value and
    the table to be altered isn't empty.
    Report error here.
  */
  if (alter_info->error_if_not_empty &&
      thd->warning_info->current_row_for_warning())
  {
    const char *f_val= 0;
    enum enum_mysql_timestamp_type t_type= MYSQL_TIMESTAMP_DATE;
    switch (alter_info->datetime_field->sql_type)
    {
      case MYSQL_TYPE_DATE:
      case MYSQL_TYPE_NEWDATE:
        f_val= "0000-00-00";
        t_type= MYSQL_TIMESTAMP_DATE;
        break;
      case MYSQL_TYPE_DATETIME:
        f_val= "0000-00-00 00:00:00";
        t_type= MYSQL_TIMESTAMP_DATETIME;
        break;
      default:
        /* Shouldn't get here. */
        DBUG_ASSERT(0);
    }
    bool save_abort_on_warning= thd->abort_on_warning;
    thd->abort_on_warning= TRUE;
    make_truncated_value_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                                 f_val, strlength(f_val), t_type,
                                 alter_info->datetime_field->field_name);
    thd->abort_on_warning= save_abort_on_warning;
  }

  DBUG_RETURN(TRUE);

err_with_mdl:
  /*
    An error happened while we were holding exclusive name metadata lock
    on table being altered. To be safe under LOCK TABLES we should
    remove all references to the altered table from the list of locked
    tables and release the exclusive metadata lock.
  */
  thd->locked_tables_list.unlink_all_closed_tables(thd, NULL, 0);
  thd->mdl_context.release_all_locks_for_name(mdl_ticket);
  DBUG_RETURN(TRUE);
}


/* Copy all rows from one table to another */



/**
  Prepare the transaction for the alter table's copy phase.
*/

bool mysql_trans_prepare_alter_copy_data(THD *thd)
{
  DBUG_ENTER("mysql_trans_prepare_alter_copy_data");
  /*
    Turn off recovery logging since rollback of an alter table is to
    delete the new table so there is no need to log the changes to it.
    
    This needs to be done before external_lock.
  */
  if (ha_enable_transaction(thd, FALSE))
    DBUG_RETURN(TRUE);
  DBUG_RETURN(FALSE);
}


/**
  Commit the copy phase of the alter table.
*/

bool mysql_trans_commit_alter_copy_data(THD *thd)
{
  bool error= FALSE;
  DBUG_ENTER("mysql_trans_commit_alter_copy_data");

  if (ha_enable_transaction(thd, TRUE))
    DBUG_RETURN(TRUE);
  
  /*
    Ensure that the new table is saved properly to disk before installing
    the new .frm.
    And that InnoDB's internal latches are released, to avoid deadlock
    when waiting on other instances of the table before rename (Bug#54747).
  */
  if (trans_commit_stmt(thd))
    error= TRUE;
  if (trans_commit_implicit(thd))
    error= TRUE;

  DBUG_RETURN(error);
}


static int
copy_data_between_tables(THD *thd, TABLE *from,TABLE *to,
			 List<Create_field> &create,
                         bool ignore,
			 uint order_num, ORDER *order,
			 ha_rows *copied,
			 ha_rows *deleted,
                         enum enum_enable_or_disable keys_onoff,
                         bool error_if_not_empty)
{
  int error= 1, errpos= 0;
  Copy_field *copy= NULL, *copy_end;
  ha_rows found_count= 0, delete_count= 0;
  uint length= 0;
  SORT_FIELD *sortorder;
  READ_RECORD info;
  TABLE_LIST   tables;
  List<Item>   fields;
  List<Item>   all_fields;
  ha_rows examined_rows;
  bool auto_increment_field_copied= 0;
  ulonglong save_sql_mode= thd->variables.sql_mode;
  ulonglong prev_insert_id, time_to_report_progress;
  List_iterator<Create_field> it(create);
  Create_field *def;
  DBUG_ENTER("copy_data_between_tables");

  /* Two or 3 stages; Sorting, copying data and update indexes */
  thd_progress_init(thd, 2 + test(order));

  if (mysql_trans_prepare_alter_copy_data(thd))
    goto err;
  errpos=1;

  if (!(copy= new Copy_field[to->s->fields]))
    goto err;		/* purecov: inspected */

  if (to->file->ha_external_lock(thd, F_WRLCK))
    goto err;
  errpos= 2;

  /* We need external lock before we can disable/enable keys */
  alter_table_manage_keys(to, from->file->indexes_are_disabled(), keys_onoff);

  /* We can abort alter table for any table type */
  thd->abort_on_warning= !ignore && test(thd->variables.sql_mode &
                                         (MODE_STRICT_TRANS_TABLES |
                                          MODE_STRICT_ALL_TABLES));

  from->file->info(HA_STATUS_VARIABLE);
  to->file->ha_start_bulk_insert(from->file->stats.records);
  errpos= 3;

  copy_end=copy;
  for (Field **ptr=to->field ; *ptr ; ptr++)
  {
    def=it++;
    if (def->field)
    {
      if (*ptr == to->next_number_field)
      {
        auto_increment_field_copied= TRUE;
        /*
          If we are going to copy contents of one auto_increment column to
          another auto_increment column it is sensible to preserve zeroes.
          This condition also covers case when we are don't actually alter
          auto_increment column.
        */
        if (def->field == from->found_next_number_field)
          thd->variables.sql_mode|= MODE_NO_AUTO_VALUE_ON_ZERO;
      }
      (copy_end++)->set(*ptr,def->field,0);
    }

  }

  if (order)
  {
    if (to->s->primary_key != MAX_KEY &&
        to->file->ha_table_flags() & HA_TABLE_SCAN_ON_INDEX)
    {
      char warn_buff[MYSQL_ERRMSG_SIZE];
      my_snprintf(warn_buff, sizeof(warn_buff), 
                  "ORDER BY ignored as there is a user-defined clustered index"
                  " in the table '%-.192s'", from->s->table_name.str);
      push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN, ER_UNKNOWN_ERROR,
                   warn_buff);
    }
    else
    {
      from->sort.io_cache=(IO_CACHE*) my_malloc(sizeof(IO_CACHE),
                                                MYF(MY_FAE | MY_ZEROFILL));
      bzero((char *) &tables, sizeof(tables));
      tables.table= from;
      tables.alias= tables.table_name= from->s->table_name.str;
      tables.db= from->s->db.str;

      thd_proc_info(thd, "Sorting");
      if (thd->lex->select_lex.setup_ref_array(thd, order_num) ||
          setup_order(thd, thd->lex->select_lex.ref_pointer_array,
                      &tables, fields, all_fields, order) ||
          !(sortorder= make_unireg_sortorder(order, &length, NULL)) ||
          (from->sort.found_records= filesort(thd, from, sortorder, length,
                                              (SQL_SELECT *) 0, HA_POS_ERROR,
                                              1, &examined_rows)) ==
          HA_POS_ERROR)
        goto err;
    }
    thd_progress_next_stage(thd);
  }

  thd_proc_info(thd, "copy to tmp table");
  /* Tell handler that we have values for all columns in the to table */
  to->use_all_columns();
  to->mark_virtual_columns_for_write(TRUE);
  if (init_read_record(&info, thd, from, (SQL_SELECT *) 0, 1, 1, FALSE))
    goto err;
  errpos= 4;
  if (ignore)
    to->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
  thd->warning_info->reset_current_row_for_warning();
  restore_record(to, s->default_values);        // Create empty record

  thd->progress.max_counter= from->file->records();
  time_to_report_progress= MY_HOW_OFTEN_TO_WRITE/10;

  while (!(error=info.read_record(&info)))
  {
    if (thd->killed)
    {
      thd->send_kill_message();
      error= 1;
      break;
    }
    if (from->vfield)
      update_virtual_fields(thd, from);
    if (++thd->progress.counter >= time_to_report_progress)
    {
      time_to_report_progress+= MY_HOW_OFTEN_TO_WRITE/10;
      thd_progress_report(thd, thd->progress.counter,
                          thd->progress.max_counter);
    }

    /* Return error if source table isn't empty. */
    if (error_if_not_empty)
    {
      error= 1;
      break;
    }
    if (to->next_number_field)
    {
      if (auto_increment_field_copied)
        to->auto_increment_field_not_null= TRUE;
      else
        to->next_number_field->reset();
    }
    
    for (Copy_field *copy_ptr=copy ; copy_ptr != copy_end ; copy_ptr++)
    {
      copy_ptr->do_copy(copy_ptr);
    }
    prev_insert_id= to->file->next_insert_id;
    if (to->vfield)
      update_virtual_fields(thd, to, VCOL_UPDATE_FOR_WRITE);
    if (thd->is_error())
    {
      error= 1;
      break;
    }
    error=to->file->ha_write_row(to->record[0]);
    to->auto_increment_field_not_null= FALSE;
    if (error)
    {
      if (!ignore ||
          to->file->is_fatal_error(error, HA_CHECK_DUP))
      {
         if (!to->file->is_fatal_error(error, HA_CHECK_DUP))
         {
           uint key_nr= to->file->get_dup_key(error);
           if ((int) key_nr >= 0)
           {
             const char *err_msg= ER(ER_DUP_ENTRY_WITH_KEY_NAME);
             if (key_nr == 0 &&
                 (to->key_info[0].key_part[0].field->flags &
                  AUTO_INCREMENT_FLAG))
               err_msg= ER(ER_DUP_ENTRY_AUTOINCREMENT_CASE);
             to->file->print_keydup_error(key_nr, err_msg, MYF(0));
             error= 1;
             break;
           }
         }

	to->file->print_error(error,MYF(0));
        error= 1;
	break;
      }
      to->file->restore_auto_increment(prev_insert_id);
      delete_count++;
    }
    else
      found_count++;
    thd->warning_info->inc_current_row_for_warning();
  }

err:
  if (errpos >= 4)
    end_read_record(&info);
  free_io_cache(from);
  delete [] copy;

  thd_proc_info(thd, "Enabling keys");
  thd_progress_next_stage(thd);

  if (error > 0)
  {
    /* We are going to drop the temporary table */
    to->file->extra(HA_EXTRA_PREPARE_FOR_DROP);
  }
  if (errpos >= 3 && to->file->ha_end_bulk_insert() && error <= 0)
  {
    to->file->print_error(my_errno,MYF(0));
    error= 1;
  }
  to->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY);

  if (errpos >= 1 && mysql_trans_commit_alter_copy_data(thd))
    error= 1;

  thd->variables.sql_mode= save_sql_mode;
  thd->abort_on_warning= 0;
  *copied= found_count;
  *deleted=delete_count;
  to->file->ha_release_auto_increment();
  if (errpos >= 2 && to->file->ha_external_lock(thd,F_UNLCK))
    error=1;
  if (error < 0 && to->file->extra(HA_EXTRA_PREPARE_FOR_RENAME))
    error= 1;
  thd_progress_end(thd);
  DBUG_RETURN(error > 0 ? -1 : 0);
}


/*
  Recreates one table by calling mysql_alter_table().

  SYNOPSIS
    mysql_recreate_table()
    thd			Thread handler
    table_list          Table to recreate

 RETURN
    Like mysql_alter_table().
*/
bool mysql_recreate_table(THD *thd, TABLE_LIST *table_list)
{
  HA_CREATE_INFO create_info;
  Alter_info alter_info;
  TABLE_LIST *next_table= table_list->next_global;

  DBUG_ENTER("mysql_recreate_table");
  /*
    table_list->table has been closed and freed. Do not reference
    uninitialized data. open_tables() could fail.
  */
  table_list->table= NULL;
  /* Same applies to MDL ticket. */
  table_list->mdl_request.ticket= NULL;
  /* Set lock type which is appropriate for ALTER TABLE. */
  table_list->lock_type= TL_READ_NO_INSERT;
  /* Same applies to MDL request. */
  table_list->mdl_request.set_type(MDL_SHARED_NO_WRITE);
  /* hide following tables from open_tables() */
  table_list->next_global= NULL;

  bzero((char*) &create_info, sizeof(create_info));
  create_info.row_type=ROW_TYPE_NOT_USED;
  create_info.default_table_charset=default_charset_info;
  /* Force alter table to recreate table */
  alter_info.flags= (ALTER_CHANGE_COLUMN | ALTER_RECREATE);
  bool res= mysql_alter_table(thd, NullS, NullS, &create_info,
                                table_list, &alter_info, 0,
                                (ORDER *) 0, 0, 0);
  table_list->next_global= next_table;
  DBUG_RETURN(res);
}


bool mysql_checksum_table(THD *thd, TABLE_LIST *tables,
                          HA_CHECK_OPT *check_opt)
{
  TABLE_LIST *table;
  List<Item> field_list;
  Item *item;
  Protocol *protocol= thd->protocol;
  DBUG_ENTER("mysql_checksum_table");

  /*
    CHECKSUM TABLE returns results and rollbacks statement transaction,
    so it should not be used in stored function or trigger.
  */
  DBUG_ASSERT(! thd->in_sub_stmt);

  field_list.push_back(item = new Item_empty_string("Table", NAME_LEN*2));
  item->maybe_null= 1;
  field_list.push_back(item= new Item_int("Checksum", (longlong) 1,
                                          MY_INT64_NUM_DECIMAL_DIGITS));
  item->maybe_null= 1;
  if (protocol->send_result_set_metadata(&field_list,
                            Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
    DBUG_RETURN(TRUE);

  /* Open one table after the other to keep lock time as short as possible. */
  for (table= tables; table; table= table->next_local)
  {
    char table_name[SAFE_NAME_LEN*2+2];
    TABLE *t;

    strxmov(table_name, table->db ,".", table->table_name, NullS);

    t= table->table= open_n_lock_single_table(thd, table, TL_READ, 0);

    protocol->prepare_for_resend();
    protocol->store(table_name, system_charset_info);

    if (!t)
    {
      /* Table didn't exist */
      protocol->store_null();
    }
    else
    {
      /* Call ->checksum() if the table checksum matches 'old_mode' settings */
      if (!(check_opt->flags & T_EXTEND) &&
          (((t->file->ha_table_flags() & HA_HAS_OLD_CHECKSUM) && thd->variables.old_mode) ||
           ((t->file->ha_table_flags() & HA_HAS_NEW_CHECKSUM) && !thd->variables.old_mode)))
	protocol->store((ulonglong)t->file->checksum());
      else if (check_opt->flags & T_QUICK)
	protocol->store_null();
      else
      {
	/* calculating table's checksum */
	ha_checksum crc= 0;
        DBUG_ASSERT(t->s->last_null_bit_pos < 8);
        uchar null_mask= (t->s->last_null_bit_pos ?
                          (256 -  (1 << t->s->last_null_bit_pos)):
                          0);

        t->use_all_columns();

	if (t->file->ha_rnd_init(1))
	  protocol->store_null();
	else
	{
	  for (;;)
	  {
            if (thd->killed)
            {
              /* 
                 we've been killed; let handler clean up, and remove the 
                 partial current row from the recordset (embedded lib) 
              */
              t->file->ha_rnd_end();
              thd->protocol->remove_last_row();
              goto err;
            }
	    ha_checksum row_crc= 0;
            int error= t->file->ha_rnd_next(t->record[0]);
            if (unlikely(error))
            {
              if (error == HA_ERR_RECORD_DELETED)
                continue;
              break;
            }
	    if (t->s->null_bytes)
            {
              /* fix undefined null bits */
              t->record[0][t->s->null_bytes-1] |= null_mask;
              if (!(t->s->db_create_options & HA_OPTION_PACK_RECORD))
                t->record[0][0] |= 1;

	      row_crc= my_checksum(row_crc, t->record[0], t->s->null_bytes);
            }

	    for (uint i= 0; i < t->s->fields; i++ )
	    {
	      Field *f= t->field[i];

              if (! thd->variables.old_mode && f->is_real_null(0))
                continue;
             /*
               BLOB and VARCHAR have pointers in their field, we must convert
               to string; GEOMETRY is implemented on top of BLOB.
               BIT may store its data among NULL bits, convert as well.
             */
              switch (f->type()) {
                case MYSQL_TYPE_BLOB:
                case MYSQL_TYPE_VARCHAR:
                case MYSQL_TYPE_GEOMETRY:
                case MYSQL_TYPE_BIT:
                {
                  String tmp;
                  f->val_str(&tmp);
                  row_crc= my_checksum(row_crc, (uchar*) tmp.ptr(),
                           tmp.length());
                  break;
                }
                default:
                  row_crc= my_checksum(row_crc, f->ptr, f->pack_length());
                  break;
	      }
	    }

	    crc+= row_crc;
	  }
	  protocol->store((ulonglong)crc);
          t->file->ha_rnd_end();
	}
      }
      trans_rollback_stmt(thd);
      close_thread_tables(thd);
      /*
        Don't release metadata locks, this will be done at
        statement end.
      */
      table->table=0;				// For query cache
    }

    if (thd->transaction_rollback_request)
    {
      /*
        If transaction rollback was requested we honor it. To do this we
        abort statement and return error as not only CHECKSUM TABLE is
        rolled back but the whole transaction in which it was used.
      */
      thd->protocol->remove_last_row();
      goto err;
    }

    /* Hide errors from client. Return NULL for problematic tables instead. */
    thd->clear_error();

    if (protocol->write())
      goto err;
  }

  my_eof(thd);
  DBUG_RETURN(FALSE);

err:
  DBUG_RETURN(TRUE);
}

/**
  @brief Check if the table can be created in the specified storage engine.

  Checks if the storage engine is enabled and supports the given table
  type (e.g. normal, temporary, system). May do engine substitution
  if the requested engine is disabled.

  @param thd          Thread descriptor.
  @param db_name      Database name.
  @param table_name   Name of table to be created.
  @param create_info  Create info from parser, including engine.

  @retval true  Engine not available/supported, error has been reported.
  @retval false Engine available/supported.
*/
static bool check_engine(THD *thd, const char *db_name,
                         const char *table_name, HA_CREATE_INFO *create_info)
{
  DBUG_ENTER("check_engine");
  handlerton **new_engine= &create_info->db_type;
  handlerton *req_engine= *new_engine;
  bool no_substitution=
        test(thd->variables.sql_mode & MODE_NO_ENGINE_SUBSTITUTION);
  if (!(*new_engine= ha_checktype(thd, ha_legacy_type(req_engine),
                                  no_substitution, 1)))
    DBUG_RETURN(true);

  if (req_engine && req_engine != *new_engine)
  {
    push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
                       ER_WARN_USING_OTHER_HANDLER,
                       ER(ER_WARN_USING_OTHER_HANDLER),
                       ha_resolve_storage_engine_name(*new_engine),
                       table_name);
  }
  if (create_info->options & HA_LEX_CREATE_TMP_TABLE &&
      ha_check_storage_engine_flag(*new_engine, HTON_TEMPORARY_NOT_SUPPORTED))
  {
    if (create_info->used_fields & HA_CREATE_USED_ENGINE)
    {
      my_error(ER_ILLEGAL_HA_CREATE_OPTION, MYF(0),
               hton_name(*new_engine)->str, "TEMPORARY");
      *new_engine= 0;
      DBUG_RETURN(true);
    }
    *new_engine= myisam_hton;
  }

  DBUG_RETURN(false);
}
