2009/9/30 Greg Smith <gsm...@gregsmith.com> > On Tue, 29 Sep 2009, Gy?rgy Vilmos wrote: > > I've done a benchmark of recent versions of PostgreSQL's last five major >> releases to see, how performance has changed during the past years from >> version to version. >> > > Your comments suggest V8.4 moves backwards as far as performance goes, > which is a bit misleading. A more fair characterization would be to > disclaim 8.4 as potentially being slower on the very simple benchmarks you > ran, not necessarily in general. > > What actually happened is some features were retuned to give better results > on difficult queries (increasing default_statistics_target is the main > example there), and one of the major maintenance tasks was removed > (adjusting the max_fsm_* parameters). These and the other 8.4 changes that > touched performance added a small amount of overhead for simple queries, but > in the situations where they help the gain can be big. > > Had you instead benchmarked a complicated query where the statistics change > caused the default behavior to provide better query plans, or you had a > deletion-heavy workload where 8.3 had trouble maintaining database free > space, you could have seen significantly better performance on 8.4. The > improvements in that version just don't help trivial examples like the > sysbench ones you ran. > > P.S. On your write-heavy tests, increasing checkpoint_segments a lot should > improve overall performance, if you re-test at some point. > Thank you very much for the valuable comments, I will keep them in mind for the next test.
BTW, this wasn't a "how could I get the maximum out of PostgreSQL", that would need much more time and research (or inner knowledge about the program). -- http://suckit.blog.hu/
