On Tue, Jan 24, 2012 at 1:26 AM, Tatsuo Ishii <ishii@postgresql.org> wrote:
>> ** pgbench, permanent tables, scale factor 100, 300 s **
>> 1 group-commit-2012-01-21 614.425851 -10.4%
>> 8 group-commit-2012-01-21 4705.129896 +6.3%
>> 16 group-commit-2012-01-21 7962.131701 +2.0%
>> 24 group-commit-2012-01-21 13074.939290 -1.5%
>> 32 group-commit-2012-01-21 12458.962510 +4.5%
>> 80 group-commit-2012-01-21 12907.062908 +2.8%
>
> Interesting. Comparing with this:
> http://archives.postgresql.org/pgsql-hackers/2012-01/msg00804.php
> you achieved very small enhancement. Do you think of any reason which
> makes the difference?
My test was run with synchronous_commit=off, so I didn't expect the
group commit patch to have much of an impact. I included it mostly to
see whether by chance it helped anyway (since it also helps other WAL
flushes, not just commits) or whether it caused any regression.
One somewhat odd thing about these numbers is that, on permanent
tables, all of the patches seemed to show regressions vs. master in
single-client throughput. That's a slightly difficult result to
believe, though, so it's probably a testing artifact of some kind.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company