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