Re: shared_buffers documentation

Robert Haas wrote:
> > Well, the point is that you are getting it for _unusual_ circumstances.
> > Seems it is only when you are getting it for typical workloads that it
> > should be increased.
>
> I guess. I am not sure we should consider "doing a large CTAS" to be
> an unusual workload, though. Sure, most of us don't do that every
> day, but what do we get out of having it be slow when we do decide to
> do it? Up until today, I had never heard anyone say that there was
> any possible performance trade-off, and...
>
> > However, this is the first time I am hearing that
> > battery-backed cache favors the default value.
>
> ...if that's as bad as it gets, I'm still not sure we shouldn't
> increase the default. Most people will not have their first
> experience of PG on a server with a battery-backed RAID controller,
> I'm thinking. And people who do have battery-backed RAID controllers
> can tune the value down if need be. I have never yet heard anyone
> justify why all the values in postgresql.conf should be defined as
> "the lowest value that works best for at least 1 user".
>
> Then again, I don't really know what I'm talking about. I think we
> should be listening very carefully to people who have spent a lot of
> time tuning this and taking their advice on how it should be set by
> default.

The current default was just chosen to reduce the PG disk footprint. It
probably should be increased, unless we find that the smaller working
set is a win in many cases.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com