Re: Re: Memory Tuning

> I am currently interested in the general issue of how to use memory
> efficiently rather than speeding up specific queries. I may revisit
> that later to see if controlling join order would help.
>
> Right now I am interested in such things such as:
>
> Should I leave postgres tuning alone and let Linux use all of the memory
> for buffer caching?

  We have a server with 512 MB of RAM, and I've tried pretty hard to get
PostgreSQL to use it all - but it just doesn't need it.  My startup line
goes like this:

su postgres -c '/usr/local/pgsql/bin/postmaster -i -S -B 8192 -N 64 -d
3 -D/usr/local/pgsql/data -o "-S 65536"'

  Now I know that I could set those numbers higher, but doing so does me no
good - PostgreSQL simply doesn't need that much memory for what we do.
They used to be set at about half of their current levels (buffers, etc.),
and I doubled them just because I could, but saw no further performance
increases or memory usage increases.   The machine generally runs with
around 275 megs doing nothing but disk cache, even under moderate usage.
The limiting factor is the CPU speed, now.  Having watched the lights on the
disks, I feel that's enough cache - the lights only give a quick blink
occasionally, when we do an insert/update.  Other than that, everything runs
out of cache.

steve