[Dovecot] Possible sort optimization (?)
Michael M Slusarz
slusarz at curecanti.org
Wed Feb 6 01:02:38 EET 2013
Maybe this is just noise... but I can reproduce this fairly reliably.
Mailbox with 21,000+ messages
This query:
a UID SORT RETURN (ALL COUNT) (DATE) UTF-8 SUBJECT "foo"
is always about 10 percent slower than this split query (I've done
this 4-5 times, and the numbers are similar):
a UID SEARCH RETURN (SAVE) CHARSET UTF-8 SUBJECT "foo"
b UID SORT RETURN (ALL COUNT) (DATE) UTF-8 UID $
(The particular query I used matched 5 messages out of the 21,000+)
My not-very-scientific benchmarking process:
1.) Stop dovecot process
2.) Delete all dovecot index files for that mailbox
3.) Flush linux paging cache (sync && echo 3 > /proc/sys/vm/drop_caches)
4.) Restart dovecot
5.) Access dovecot via command-line (PREAUTH)
6.) SELECT mailbox
7.) Issue command(s)
Could be a potential area for performance improvement or could simply
be lazy benchmarking.
michael
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