On Tue, Feb 14, 2012 at 10:57 PM, Venkat Balaji <venkat.balaji@xxxxxxxx> wrote: > > On Wed, Feb 15, 2012 at 1:35 AM, Jay Levitt <jay.levitt@xxxxxxxxx> wrote: >> >> We need to do a few bulk updates as Rails migrations. We're a typical >> read-mostly web site, so at the moment, our checkpoint settings and WAL are >> all default (3 segments, 5 min, 16MB), and updating a million rows takes 10 >> minutes due to all the checkpointing. >> >> We have no replication or hot standbys. As a consumer-web startup, with >> no SLA, and not a huge database, and if we ever do have to recover from >> downtime it's ok if it takes longer.. is there a reason NOT to always run >> with something like checkpoint_segments = 1000, as long as I leave the >> timeout at 5m? > > > Still checkpoints keep occurring every 5 mins. Anyways > checkpoint_segments=1000 is huge, this implies you are talking about > 16MB * 1000 = 16000MB worth pg_xlog data, which is not advisable from I/O > perspective and data loss perspective. Even in the most unimaginable case if > all of these 1000 files get filled up in less than 5 mins, there are chances > that system will slow down due to high IO and CPU. As far as I know there is no data loss issue with a lot of checkpoint segments. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
