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. PG 9.4.1 shall be actually better in relation extension handling - a possible explanation is that your 9.3.5 database has been used for a while thus there are holes in pages, so not many extensions are required. > > a) I'm assuming "extension" means growing the physical diskspace used by a > table-- is that correct? Yes. > b) How can you find the name of the relation being extended? based on the > relation number. select <number>::regclass; > c) Why would Postgres grow a table twice in the same millisecond? Could it > be an index with a high fill factor? PG extends one page each time when new space needed. > 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. Regards, Qingqing -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
