Although I don't have an answer, I can confirm the slow query happens on
3.2.1, though for me at least unrepeatable, subsequent runs of the query
are returned sub second.
The query planner shows nothing unusual, also table stats for each of
the query tables shows few table scans. Fortunately it hasn't affected
me enough to investigate further.
I haven't tried header_cache_readonly which may help.
Currently running PostgreSQL 9.2, previously saw more on MySQL 5.1
though no stats to compare fairly.
Regards,
Alan
On 24/11/2014 10:51, Daniel Schütze wrote:
I’ve noticed in my slow query log there is a particular type of query
which is regularly showing up and I was wondering what was triggering it.
The most recent example is this (but it’s being going on since I
turned the slow query log on in July:
SELECT m.message_idnr, n.headername, v.headervalue, CASE WHEN
n.headername='from' THEN 0 WHEN n.headername='to' THEN 1 WHEN
n.headername='cc' THEN 2 WHEN n.headername='bcc' THEN 3 WHEN
n.headername='subject' THEN 4 WHEN n.headername='date' THEN 5 WHEN
n.headername='message-id' THEN 6 WHEN n.headername='priority' THEN 7
WHEN n.headername='x-priority' THEN 8 WHEN n.headername='references'
THEN 9 WHEN n.headername='newsgroups' THEN 10 WHEN
n.headername='in-reply-to' THEN 11 WHEN n.headername='content-type'
THEN 12 WHEN n.headername='reply-to' THEN 13 END AS seq FROM
dbmail_header h LEFT JOIN dbmail_messages m ON
h.physmessage_id=m.physmessage_id LEFT JOIN dbmail_headername n ON
h.headername_id=n.id LEFT JOIN dbmail_headervalue v ON
h.headervalue_id=v.id WHERE m.mailbox_idnr = 170 AND m.message_idnr
BETWEEN 5477613 AND 5479501 AND n.headername IN
('from','to','cc','bcc','subject','date','message-id','priority','x-priority','references','newsgroups','in-reply-to','content-type','reply-to')
ORDER BY message_idnr, seq;
Which slow reports as taking some 33 seconds
# Time: 141124 10:32:05
# User@Host: dbmail[dbmail] @ localhost []
# Query_time: 33.363653 Lock_time: 0.000014 Rows_sent: 0
Rows_examined: 20214893
I’m still using dbmail 3.1.15 so apologies if this is obsolete by the
current 3.2.1 release; but I’m wondering if this query/speed is normal
or a sign something is a miss.
Regards
Daniel Schütze
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