Re: postgres and cache

* Merrill Oveson <merrill(at)actarg(dot)com> [000810 16:50] wrote:
> Greetings:
>
> Upgraded server from a Dual PII-400 to a Dual PIII-750 with Mylex
> RAID-5. We didn't really see an increase of speed, or at least not what
> we expected.
>
> In our quest for speed we put the data onto a RAM drive and the
> queries completed in a third the time. I wouldn't expect to see this
> type of speed gain from a RAM drive because the tables are small enough
> to easily fit into cache. So my question is...Does Postgres force a
> flush to disk while it's working on particular types of queries?

It most certainly does, here's a few tips that may imporve performance:

pass the -F option to the backend so that it doesn't fsync on every
write.

check the manual for ways of increasing the amount of shared memory
buffers that postgresql will attempt to allocate, you may also need
to consult your OS's documentation for directions on increasing those
reasources as well.

best of luck.
--
-Alfred Perlstein - [bright(at)wintelcom(dot)net|alfred(at)freebsd(dot)org]
"I have the heart of a child; I keep it in a jar on my desk."