Jay Levitt 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? There's nothing wrong with the idea except for the amount of WAL and a huge checkpoint that can stall your system for a while in a worst-case scenario. You can't get rid of checkpoint I/O completely. I'd tune to a more conservative value, maybe 30 or at most 100 and see if that solves your problem. Check statistics to see if checkpoints are time-driven or not. As soon as almost all checkpoints are time- driven, further raising of checkpoint_segments won't do anything for you. Yours, Laurenz Albe -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
