[rt-users] Postgresql 4.4.1 slow queries?

Joel Bergmark joel.bergmark at t3.se
Tue Sep 27 03:52:52 EDT 2016


After upgrading to version 4.4.1 i have noticed that the SQL-queries takes significant longer time to produce a result, on average on my system, running Ubuntu 14.04 LTS, Postgres 9.3, Apache with perlmod. 8 gigram and plenty of CPU in a vmware cluster on SSD:s (likely not a hardware issue). We did not experience RT to have been this slow on 4.4.0.

Each query takes about 350ms to give a result, occasionally up to 4000ms have been seen, not a big problem but somethings that needs to be fixed.

Postgres have access to shared buffers = 2048 and effective_cache_size = 4096MB that was modified yesterday but queries still are same speed.

I have read plenty on postgres optimizing but not much seem to make a difference, and the https://rt-wiki.bestpractical.com/wiki/PerformanceTuning seems a bit out of date.

Example of problem: - - [27/Sep/2016:09:06:49 +0200] "GET /Search/Build.html?NewQuery=1 HTTP/1.1" 200 12072 Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.101 Safari/537.36"
09:06:52 CEST LOG:  duration: 3362.432 ms  execute dbdpg_p2242_1745: SELECT DISTINCT main.* FROM Users main CROSS JOIN ACL ACL_3 JOIN Principals Principals_1  ON ( Principals_1.id = main.id ) JOIN CachedGroupMembers CachedGroupMembers_2  ON ( CachedGroupMembers_2.MemberId = Principals_1.id ) JOIN CachedGroupMembers CachedGroupMembers_4  ON ( CachedGroupMembers_4.MemberId = Principals_1.id )  WHERE ((ACL_3.ObjectType = 'RT::Queue') OR (ACL_3.ObjectType = 'RT::System' AND ACL_3.ObjectId   = 1)) AND (ACL_3.PrincipalId = CachedGroupMembers_4.GroupId) AND (ACL_3.PrincipalType = 'Group') AND (ACL_3.RightName = 'OwnTicket' OR ACL_3.RightName = 'SuperUser') AND (CachedGroupMembers_2.Disabled = '0') AND (CachedGroupMembers_2.GroupId = '4') AND (CachedGroupMembers_4.Disabled = '0') AND (Principals_1.Disabled = '0') AND (Principals_1.PrincipalType = 'User') AND (Principals_1.id != '1')  ORDER BY main.Name ASC
I'm looking for any suggestions about this, and I'm not an expert on postgresql, but guess that this could have something to do with RT:s "($UseSQLForACLChecks, 1);" or modperl via Apache or simply some index in postgres?

Appreciate any feedback :-)

Regards, Joel

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