Vlad Bailescu <vlad@xxxxxxxxxxxxxxxxxx> wrote: > Because of our application stack (Hibernate ORM) we use a > before_insert trigger to insert rows into the right partition and > in the master table and then an after_insert trigger to delete > them from master table (we need the original insert to return the > inserted row info). This means the master table becomes quickly > populated with dead tuples and triggers the autovacuum frequently > (we are using default settings for autovacuum). > > After upgrading our DB from 8.4 to 9.1 (and moving from Debian 6 > to Ubuntu 12.04) we noticed a large increase in IO and traced it > back to auto vacuum: iotop and collectd report bursts of 4-6M/s > taking 90 seconds followed by a 30 seconds pause. That's a lot of > data to chew on especially since the master table is only a > couple of megabytes (indexes included). > > Can anyone please explain why this is happening and how we can > get around it? It sounds like it could be an issue which will be fixed in the next minor release: http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=5454344b968d6a189219cfd49af609a3e7d6af33 If this is the issue, a periodic manual VACUUM of the master table should help for now. When 9.1.8 is released you might want to upgrade without a lot of delay, and see if you are then OK without the manual vacuums. -Kevin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
