WiredTiger: ex_schema.c

| Version 3.1.0

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ex_schema.c

Shows how to create column-oriented data and access individual columns.

/*-
* Public Domain 2014-2018 MongoDB, Inc.
* Public Domain 2008-2014 WiredTiger, Inc.
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ex_schema.c
* This is an example application demonstrating how to create and access
* tables using a schema.
*/
#include <test_util.h>
static const char *home;
/* The C struct for the data we are storing in a WiredTiger table. */
typedef struct {
char country[5];
uint16_t year;
uint64_t population;
} POP_RECORD;
static POP_RECORD pop_data[] = {
{ "AU", 1900, 4000000 },
{ "AU", 1950, 8267337 },
{ "AU", 2000, 19053186 },
{ "CAN", 1900, 5500000 },
{ "CAN", 1950, 14011422 },
{ "CAN", 2000, 31099561 },
{ "UK", 1900, 369000000 },
{ "UK", 1950, 50127000 },
{ "UK", 2000, 59522468 },
{ "USA", 1900, 76212168 },
{ "USA", 1950, 150697361 },
{ "USA", 2000, 301279593 },
{ "", 0, 0 }
};
int
main(int argc, char *argv[])
{
POP_RECORD *p;
WT_CONNECTION *conn;
WT_CURSOR *country_cursor, *country_cursor2, *cursor, *join_cursor,
*stat_cursor, *subjoin_cursor, *year_cursor;
WT_SESSION *session;
const char *country;
uint64_t recno, population;
uint16_t year;
int ret;
home = example_setup(argc, argv);
error_check(wiredtiger_open(
home, NULL, "create,statistics=(fast)", &conn));
error_check(conn->open_session(conn, NULL, NULL, &session));
/*
* Create the population table.
* Keys are record numbers, the format for values is (5-byte string,
* uint16_t, uint64_t).
* See ::wiredtiger_struct_pack for details of the format strings.
*/
error_check(session->create(session, "table:poptable",
"key_format=r,"
"value_format=5sHQ,"
"columns=(id,country,year,population),"
"colgroups=(main,population)"));
/*
* Create two column groups: a primary column group with the country
* code, year and population (named "main"), and a population column
* group with the population by itself (named "population").
*/
error_check(session->create(session,
"colgroup:poptable:main", "columns=(country,year,population)"));
error_check(session->create(session,
"colgroup:poptable:population", "columns=(population)"));
/* Create an index with a simple key. */
error_check(session->create(session,
"index:poptable:country", "columns=(country)"));
/* Create an index with a composite key (country,year). */
error_check(session->create(session,
"index:poptable:country_plus_year", "columns=(country,year)"));
/* Create an immutable index. */
error_check(session->create(session,
"index:poptable:immutable_year", "columns=(year),immutable"));
/* Insert the records into the table. */
error_check(session->open_cursor(
session, "table:poptable", NULL, "append", &cursor));
for (p = pop_data; p->year != 0; p++) {
cursor->set_value(cursor, p->country, p->year, p->population);
error_check(cursor->insert(cursor));
}
error_check(cursor->close(cursor));
/* Update records in the table. */
error_check(session->open_cursor(session,
"table:poptable", NULL, NULL, &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &recno));
error_check(cursor->get_value(
cursor, &country, &year, &population));
cursor->set_value(cursor, country, year, population + 1);
error_check(cursor->update(cursor));
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/* List the records in the table. */
error_check(session->open_cursor(session,
"table:poptable", NULL, NULL, &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &recno));
error_check(cursor->get_value(
cursor, &country, &year, &population));
printf("ID %" PRIu64, recno);
printf(
": country %s, year %" PRIu16 ", population %" PRIu64 "\n",
country, year, population);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/* List the records in the table using raw mode. */
error_check(session->open_cursor(session,
"table:poptable", NULL, "raw", &cursor));
while ((ret = cursor->next(cursor)) == 0) {
WT_ITEM key, value;
error_check(cursor->get_key(cursor, &key));
error_check(wiredtiger_struct_unpack(
session, key. data, key. size, "r", &recno));
printf("ID %" PRIu64, recno);
error_check(cursor->get_value(cursor, &value));
error_check(wiredtiger_struct_unpack(session,
value.data, value.size,
"5sHQ", &country, &year, &population));
printf(
": country %s, year %" PRIu16 ", population %" PRIu64 "\n",
country, year, population);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/*
* Open a cursor on the main column group, and return the information
* for a particular country.
*/
error_check(session->open_cursor(
session, "colgroup:poptable:main", NULL, NULL, &cursor));
cursor->set_key(cursor, 2);
error_check(cursor->search(cursor));
error_check(cursor->get_value(cursor, &country, &year, &population));
printf(
"ID 2: country %s, year %" PRIu16 ", population %" PRIu64 "\n",
country, year, population);
error_check(cursor->close(cursor));
/*
* Open a cursor on the population column group, and return the
* population of a particular country.
*/
error_check(session->open_cursor(session,
"colgroup:poptable:population", NULL, NULL, &cursor));
cursor->set_key(cursor, 2);
error_check(cursor->search(cursor));
error_check(cursor->get_value(cursor, &population));
printf("ID 2: population %" PRIu64 "\n", population);
error_check(cursor->close(cursor));
/* Search in a simple index. */
error_check(session->open_cursor(session,
"index:poptable:country", NULL, NULL, &cursor));
cursor->set_key(cursor, "AU\0\0\0");
error_check(cursor->search(cursor));
error_check(cursor->get_value(cursor, &country, &year, &population));
printf("AU: country %s, year %" PRIu16 ", population %" PRIu64 "\n",
country, year, population);
error_check(cursor->close(cursor));
/* Search in a composite index. */
error_check(session->open_cursor(session,
"index:poptable:country_plus_year", NULL, NULL, &cursor));
cursor->set_key(cursor, "USA\0\0", (uint16_t)1900);
error_check(cursor->search(cursor));
error_check(cursor->get_value(cursor, &country, &year, &population));
printf(
"US 1900: country %s, year %" PRIu16 ", population %" PRIu64 "\n",
country, year, population);
error_check(cursor->close(cursor));
/*
* Use a projection to return just the table's country and year
* columns.
*/
error_check(session->open_cursor(session,
"table:poptable(country,year)", NULL, NULL, &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_value(cursor, &country, &year));
printf("country %s, year %" PRIu16 "\n", country, year);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/*
* Use a projection to return just the table's country and year
* columns, using raw mode.
*/
error_check(session->open_cursor(session,
"table:poptable(country,year)", NULL, "raw", &cursor));
while ((ret = cursor->next(cursor)) == 0) {
WT_ITEM value;
error_check(cursor->get_value(cursor, &value));
error_check(wiredtiger_struct_unpack(
session, value.data, value.size, "5sH", &country, &year));
printf("country %s, year %" PRIu16 "\n", country, year);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/*
* Use a projection to return just the table's record number key
* from an index.
*/
error_check(session->open_cursor(session,
"index:poptable:country_plus_year(id)", NULL, NULL, &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &country, &year));
error_check(cursor->get_value(cursor, &recno));
printf("row ID %" PRIu64 ": country %s, year %" PRIu16 "\n",
recno, country, year);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/*
* Use a projection to return just the population column from an
* index.
*/
error_check(session->open_cursor(session,
"index:poptable:country_plus_year(population)",
NULL, NULL, &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &country, &year));
error_check(cursor->get_value(cursor, &population));
printf("population %" PRIu64 ": country %s, year %" PRIu16 "\n",
population, country, year);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/*
* Use a projection to avoid accessing any other column groups when
* using an index: supply an empty list of value columns.
*/
error_check(session->open_cursor(session,
"index:poptable:country_plus_year()", NULL, NULL, &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &country, &year));
printf("country %s, year %" PRIu16 "\n", country, year);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
/* Open cursors needed by the join. */
error_check(session->open_cursor(session,
"join:table:poptable", NULL, NULL, &join_cursor));
error_check(session->open_cursor(session,
"index:poptable:country", NULL, NULL, &country_cursor));
error_check(session->open_cursor(session,
"index:poptable:immutable_year", NULL, NULL, &year_cursor));
/* select values WHERE country == "AU" AND year > 1900 */
country_cursor->set_key(country_cursor, "AU\0\0\0");
error_check(country_cursor->search(country_cursor));
error_check(session->join(
session, join_cursor, country_cursor, "compare=eq,count=10"));
year_cursor->set_key(year_cursor, (uint16_t)1900);
error_check(year_cursor->search(year_cursor));
error_check(session->join(session,
join_cursor, year_cursor, "compare=gt,count=10,strategy=bloom"));
/* List the values that are joined */
while ((ret = join_cursor->next(join_cursor)) == 0) {
error_check(join_cursor->get_key(join_cursor, &recno));
error_check(join_cursor->get_value(
join_cursor, &country, &year, &population));
printf("ID %" PRIu64, recno);
printf(
": country %s, year %" PRIu16 ", population %" PRIu64 "\n",
country, year, population);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(session->open_cursor(session,
"statistics:join",
join_cursor, NULL, &stat_cursor));
error_check(stat_cursor->close(stat_cursor));
error_check(join_cursor->close(join_cursor));
error_check(year_cursor->close(year_cursor));
error_check(country_cursor->close(country_cursor));
/* Open cursors needed by the join. */
error_check(session->open_cursor(session,
"join:table:poptable", NULL, NULL, &join_cursor));
error_check(session->open_cursor(session,
"join:table:poptable", NULL, NULL, &subjoin_cursor));
error_check(session->open_cursor(session,
"index:poptable:country", NULL, NULL, &country_cursor));
error_check(session->open_cursor(session,
"index:poptable:country", NULL, NULL, &country_cursor2));
error_check(session->open_cursor(session,
"index:poptable:immutable_year", NULL, NULL, &year_cursor));
/*
* select values WHERE (country == "AU" OR country == "UK")
* AND year > 1900
*
* First, set up the join representing the country clause.
*/
country_cursor->set_key(country_cursor, "AU\0\0\0");
error_check(country_cursor->search(country_cursor));
error_check(session->join(session, subjoin_cursor,
country_cursor, "operation=or,compare=eq,count=10"));
country_cursor2->set_key(country_cursor2, "UK\0\0\0");
error_check(country_cursor2->search(country_cursor2));
error_check(session->join(session, subjoin_cursor,
country_cursor2, "operation=or,compare=eq,count=10"));
/* Join that to the top join, and add the year clause */
error_check(session->join(session, join_cursor, subjoin_cursor, NULL));
year_cursor->set_key(year_cursor, (uint16_t)1900);
error_check(year_cursor->search(year_cursor));
error_check(session->join(session,
join_cursor, year_cursor, "compare=gt,count=10,strategy=bloom"));
/* List the values that are joined */
while ((ret = join_cursor->next(join_cursor)) == 0) {
error_check(join_cursor->get_key(join_cursor, &recno));
error_check(join_cursor->get_value(
join_cursor, &country, &year, &population));
printf("ID %" PRIu64, recno);
printf(
": country %s, year %" PRIu16 ", population %" PRIu64 "\n",
country, year, population);
}
scan_end_check(ret == WT_NOTFOUND);
error_check(join_cursor->close(join_cursor));
error_check(subjoin_cursor->close(subjoin_cursor));
error_check(country_cursor->close(country_cursor));
error_check(country_cursor2->close(country_cursor2));
error_check(year_cursor->close(year_cursor));
error_check(conn->close(conn, NULL));
return (EXIT_SUCCESS);
}