[Dovecot] body search very slow since upgrade from 1.0.15 to 1.2.10

[Stan Hoeppner]

Timo Sirainen put forth on 2/23/2010 12:33 PM:
> On 23.2.2010, at 16.19, Stan Hoeppner wrote:
> 
>> Did you mislead me Timo?  You said search in 1.1+ is faster than 1.0.  I'm
>> seeing approximately 20x *slower* search times in 1.2.10.
>>
>> Via Thunderbird, a full body search of my 11,000+ message IMAP folder hosted
>> by 1.0.15 used to take less than 10 seconds.  Since upgrading to 1.2.10 the
>> search is taking over 3 minutes, the imap process servicing the client
>> pegging one CPU at 100% for the duration of the search.  Here's the mbox file:
> 
> Well, v1.1+ does case-insensitive searches by converting all mails to UTF-8 first. But it really shouldn't make it that much slower. What OS and CPU is this with?

Debian 5.0.4
Linux kernel 2.6.31.1 rolled by me from kernel.org source
Dovecot, Debian backport Version: 1:1.2.10-1~bpo50+1
Intel 440BX Abit BP6 mobo, Dual Mendocino Celerons @550 MHz, 384MB PC100

> You could also try if it happens to work faster by compiling Dovecot without iconv support.

Was iconv support in dovecot 1.0.15?  How can I check to see if my dovecot
1.2.10 already has iconv support?  Is there a dovecot command similar to
postconf -m which shows what database types were compiled into the postfix
binaries?

> I guess there could also be some kind of a bug that you're triggering.

Is there any setting in dovecot.conf, that if set incorrectly, could cause
this?  If not, and assuming the Debian team didn't screw up the package, I'd
lean toward this bug explanation, except that no one else is reporting this
problem, are they?

These searches used to take about 10 seconds on 1.0.15.  They're taking 3
minutes or more on 1.2.10.  Also, on 1.0.15, if I ran the same search
back-to-back, the second search completed _instantly_.  On 1.2.10, the
second search takes as long as the first.  This leads me to believe the
indexes and caches aren't being used at all during the searches, or
something along these lines.  Shouldn't they be?

Again, if grep can do these searches in less than a second, there's no
reason why imap can't do them in 10 seconds.  Something has got to be
horribly wrong here...

Tell me what I need to do to fix this, whilst not having to go outside the
Debian package system.

Thanks.

-- 
Stan