Re: Performance evaluation of PostgreSQL's historic releases

2009/9/30 Greg Smith <gsmith(at)gregsmith(dot)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).

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