On 2015-04-16 14:23:25 -0700, Qingqing Zhou wrote: > On Thu, Apr 16, 2015 at 1:24 PM, Andomar <andomar@xxxxxxxx> wrote: > > After upgrading our database from 9.3.5 to 9.4.1 last night, the server > > suffers from high CPU spikes. During these spikes, there are a lot of these > > messages in the logs: > > > > process X still waiting for ExclusiveLock on extension of relation Y of > > database Z after 1036.234 ms > > > This issue has been complained several times, and here is the most recent one: > http://www.postgresql.org/message-id/0DDFB621-7282-4A2B-8879-A47F7CECBCE4@xxxxxxxxxxx > > PG 9.4.1 shall have much alleviated it by relaxing buffer pool related > locks. Hm. I'm not aware of related changes in 9.4? 9.5 should be a bit better, but I don't think 9.4 will make much of a difference. > > b) How can you find the name of the relation being extended? based on the > > relation number. > select <number>::regclass; That's not correct. The relfilenode is only equivalent to the relation's oid when you initially create it. But once rewritten it'll change. Rather use SELECT oid::regclass FROM pg_class WHERE pg_relation_filenode(oid) = 2937136; > > Any suggestions on how to approach this issue are welcome. > > > There are some diagnosis in above link, see if it rings any bell. From > PG kernel side, I think fundamentally we may want to extend many pages > each time instead of one. I don't really agree that that's the most important bit. See http://archives.postgresql.org/message-id/20150329185619.GA29062%40alap3.anarazel.de Greetings, Andres Freund -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
