Re: Logging WAL when updating hintbit

On 20 November 2013 22:12, Sawada Masahiko Wrote

> >
> > 1. Patch applies cleanly to master HEAD.
> > 2. No Compilation Warning.
> > 3. It works as per the patch expectation.
> >
> > Some Suggestion:
> > 1. Add new WAL level ("all") in comment in postgresql.conf
> > wal_level = hot_standby # minimal, archive,
> or hot_standby
>
> Thank you for reviewing the patch.
> Yes, I will do that. And I'm going to implement documentation patch.

OK, once I get it, I will review the same.

> >
> > Performance Test Result:
> > Run with pgbench for 300 seconds
> >
> > WAL level : hot_standby
> > WAL Size : 111BF8A8
> > TPS : 125
> >
> > WAL level : all
> > WAL Size : 11DB5AF8
> > TPS : 122
> >
> > * TPS is almost constant but WAL size is increased around 11M.
> >
> > This is the first level of observation, I will continue to test few
> more scenarios including performance test on standby.
>
> Thank you for performance testing.
> According of test result, TPS of 'all' lower than 'hot_standby',but
> WAL size is increased.
> I think that it should be separate parameter.
> And TPS on master side is is almost constant. so this patch might have
> several benefit for performance improvement on standby side if the
> result of performance test on standby side is improved.

[Performance test on standby:]

I have executed pgbench on master with WAL LEVEL "hot_stanby" and "all" option, and after that run pgbench on standby with "select-only" option.

WAL LEVEL (on master) : hot_standby
Select TPS (on standby) : 4098

WAL LEVEL (on master) : all
Select TPS (on standby) : 4115

Regards,
Dilip