Re: wal_buffer tests in

On Wed, 27 Jul 2005 13:30:01 -0700
Josh Berkus <josh@agliodbs.com> wrote:

> Folks,
> 
> I ran a wal_buffer test series.   It appears that increasing the 
> wal_buffers is indeed very important for OLTP applications, potentially 
> resulting in as much as a 15% average increase in transaction processing.  
> What's interesting is that this is not just true for 8.1, it's true for 
> 8.0.3 as well.   
> 
> More importantly, 8.1 performance is somehow back up to above-8.0 levels.  
> Something was broken in June that's got fixed (this test series is based 
> on July 3 CVS) but I don't know what.  Clues?
> 
> Test results are here:
> http://pgfoundry.org/docman/view.php/1000041/79/wal_buffer_test.pdf
> 
> As always, detailed test results are available from OSDL, just use:
> http://khack.osdl.org/stp/#
> where # is the test number.

The increase could actually be higher than 15% as 1800 notpm is about
the max throughput you can have with 150 warehouses with the default
thinktimes.  The rule of thumb is about 12 * warehouses, for the
throughput.

Mark