[Dovecot] Very slow select() command on large mailboxes

[Timo Sirainen]

On Thu, 2005-07-14 at 11:59 +0200, Sebastjan Trepca wrote:
> Hi,
> 
> I'm trying to decide if I could use you mail server in our enviroment
> which has about 10k users and mailboxes size about ~1GB. 
> So I made a few tests and it all worked quite fast, except that select
> command on large mailboxes. The first time I select a mailbox which
> has 10k messages it takes about 4s to process. I am deliberately
> trying this on a Celeron 850Mhz, 512 MB memory and some shitty
> hard-drive to maximize the times.
> So why is this so slow? Does it index the messages on select? It's
> even slower when I have some new messages in folder, more that I have
> more I wait. So I presume it must be something with indexing? Anyway,
> how could I optimize this? Why don't you index when a mail arrives
> instead of on select? 

mbox or maildir? mbox can be optimized in different ways with
1.0-stable/test releases, but maildir itself needs to be rescanned all
too often..