Op 5-nov-03 om 23:39 heeft Eric Soroos het volgende geschreven:
I have used Evolution, Outlook Express, Mozilla, Thunderbird and to a
lesser extent Outlook. They all work well. To me the main reason to
use dbmail is for IMAP. Traditional unix based imap servers really
hit a performance wall when mailboxes start getting big. dbmail is
MUCH better. I have several mailboxes with well over 25,000 messages
in them, and dbmail doesn't blink.
Maybe it's just my setup, but I've found that synching a 18k item
mailbox gets me a message or two a seconds. Smaller mailboxes are damn
fast.
I'm on debian/stable, updated as of yesterday, running postgresql. The
client is mail.app.
I actually did a bunch of looking at this yesterday, and I think I
can trace it down to a call to db_getmailbox in the course of a uid
fetch command. Since mail.app grabs 2 messages at a time, it's
tablescanning the mailbox table, then sorting, for each two messages.
(This is really because this mailbox is 1/2 the total messages in the
system, so it resorts to tablescanning)
I looked at the 1.2 source and couldn't find the offending call to
db_getmailbox, so I'm in the process of pulling the debian 1.1-1
sources to see how different they are.
Could you set the tracelevel to 5 and send the exact imap commands
mail.app is generating? This way we might be able to speed things up a
bit.
I've also noticed that after every inserted message, there is one
query per folder on my mailbox to determine the total size of my
account. Setting aside the fact that I don't have a quota on my
account, there's no possible need run 20 queries when one join would
do. e.g. select sum(messages.rfcSize) from messages inner join
mailboxes using (mailbox_idnr) where mailbox.owner_idnr='me'. It
would still be a table scan, but at least it would just be one table
scan. (see db_check_sizelimit)
Well, this problem is being addressed in 2.0 - it uses a new field in
the user table which keeps track of the current amount of mail in all
the folders for a certain user. This enables us to determine the
current mailbox size with one real fast query. The reason we currently
use a number of queries instead of one JOINed is performance; we have
encountered numerous cases where looping simple queries performs way
better than having the sql backend joining tables (though i'm not
completely sure this is such a case ;-)
regards
roel
eric
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