On Tue, Jul 1, 2014 at 7:36 AM, AI Rumman <rumman...@gmail.com> wrote:
> I see lots of similar log message at a certain time in a day on Postgresql > 9,.1: > > LOG: process 18855 still waiting for ShareLock on transaction 2856146023 > after 1001.209 ms > STATEMENT: UPDATE table1 SET time = $1 WHERE id = $2 > > The table1 size is 17 G. > > What could be the reason for this lock contention? > autovacuum? > This may be a CREATE INDEX query taking some time, perhaps combined with an old prepared transaction still holding a lock? Perhaps a cron job running behind that you are not aware of? You should have a look at pg_stat_activity, pg_prepared_xacts and pg_locks to get more information about the transactions running and the locks being taken. -- Michael