[Imap-uw] Why Postfix/local is so much faster than UW/tmail?

[Mark Crispin]

On Thu, 27 Sep 2007, "Ing.BcA. Ivan Doležal" wrote:
>   Postfix is the SMTP server and it provides its "local" utility to deliver 
> a mail to MBOX, which does very fast. Today, in preparation to switch, I 
> changed mailbox_transport to tmail and the server died with load >700 during 
> regular working day.
>   Why this?

postfix's local utility undoubtably just appends new messages to the end 
of the mailbox.  tmail on the other hand must maintain an IMAP UID regime;
this requires scanning the entire mailbox in traditional UNIX format.

tmail used to work like postfix, but the requirement to implement UIDPLUS 
forced the more complicated (and slow) code.  This is why I never wanted 
to implement UIDPLUS; I knew that this would happen.  Unfortunately, there 
is a generation of IMAP clients that consider the UIDPLUS option as
mandatory.

> Should this remarkably improve with switching to MIX?

Yes.  Unlike traditional UNIX format, mix was designed with UIDPLUS in 
mind.

-- Mark --

http://panda.com/mrc
Democracy is two wolves and a sheep deciding what to eat for lunch.
Liberty is a well-armed sheep contesting the vote.