Re: shared_buffers documentation

Robert Haas <robertmhaas@gmail.com> wrote:
> 2. Reading the section on checkpoint_segments reminds me, again,
> that the current value seems extremely conservative on modern
> hardware.  It's quite easy to hit this when doing large bulk data
> loads or even a big ol' CTAS.  I think we should consider raising
> this for 9.1.
Perhaps, but be aware the current default benchmarked better
than a larger setting in bulk loads.
http://archives.postgresql.org/pgsql-hackers/2009-06/msg01382.php
The apparent reason is that when there were fewer of them the WAL
files were re-used before the RAID controller flushed them from BBU
cache, causing an overall reduction in disk writes.  I have little
doubt that *without* a good BBU cached controller a larger setting
is better, but it's not universally true that bigger is better on
this one.
-Kevin