Subject: [Imap-uw] Large mailboxes: limits, algorithmical complexity?

From: "Aaron W. LaFramboise" <[email-masked]>
Date: Fri, 03 Feb 2006 19:46:45 -0600

Hello :)

1) My gcc-patches mailbox, MBX, recently passed 50k messages.  I'm a 
little curious whats going to happen at 65k.  What is the maximum amount 
of message allowed?  Is there a maximum total disk size?  (So far, the 
mailbox only takes about 300MB or about 7KB per message.)

2) What is the algorithmical complexity of selecting and synchronizing a 
MBX mailbox?  On my machine, it appears to be roughly proportional to 
the time it takes to 'cat' the mailbox, so I'd suspect its linear.  The 
above mailbox takes about five seconds to open on an unloaded machine 
with a clear disk cache (or about half a second if its in cache).

2.5) Is there any possibility of a c-client compatible mailbox format 
for which selecting, synchronizing, and other common operations are 
constant-time?  Presently my mail usually takes about half a minute to 
open (There are many folders.), and if I could get that down to less 
than a second, I'd be tickled silly.

Thanks in advance for any insight and advice!

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---

From: Mark Crispin <[email-masked]>
Date: Fri, 3 Feb 2006 18:31:23 -0800 (Pacific Standard Time)

On Fri, 3 Feb 2006, Aaron W. LaFramboise wrote:
> 1) My gcc-patches mailbox, MBX, recently passed 50k messages.  I'm a little 
> curious whats going to happen at 65k.

Nothing special.

> What is the maximum amount of message allowed?

It's limited only by virtual memory on your system and your disk's 
filesystem.

> Is there a maximum total disk size?  (So far, the mailbox only 
> takes about 300MB or about 7KB per message.)

On many UNIX systems, the limit is 2GB.

> 2) What is the algorithmical complexity of selecting and synchronizing a MBX 
> mailbox?  On my machine, it appears to be roughly proportional to the time it 
> takes to 'cat' the mailbox, so I'd suspect its linear.

It is linear following the number of messages in the mailbox.

With traditional UNIX mailbox format, it is linear following the number of 
bytes in the file.

> 2.5) Is there any possibility of a c-client compatible mailbox format for 
> which selecting, synchronizing, and other common operations are 
> constant-time?

I am developing such a format now.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.
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