>>> Alexander Staubo <alex@xxxxxxxxxx> wrote: > Kevin Grittner <Kevin.Grittner@xxxxxxxxxxxx> wrote: >> Could you show the non-commented lines from old and new >> postgresql.conf files, please? > > Attached. The differences are not performance-related, as far as I > can see, aside from the additional of "synchronous_commit = off". You should definitely set effective_cache_size. If you still see the problem after that, I suggest testing different settings for: bgwriter_lru_maxpages bgwriter_lru_multiplier checkpoint_segments checkpoint_timeout checkpoint_completion_target Both the checkpoint process and the background writer changed quite a bit, and these are the main knobs for tuning the new version. It's possible that under 8.2 your hint bit writes were being combined with other writes due to caching, and differences in the timings now have the hint bit writes happening too long after the initial write to get that benefit. If that's the case, the counterintuitive step of making PostgreSQL more aggressive about writing to the OS cache might reduce your disk write I/O. Making it less aggressive might allow them to combine in the PostgreSQL buffers before making to the OS cache. -Kevin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
