Re: Large database help

pgsql/PG_VERSION says "7.0". postmaster --version and psql --version don't
tell me anything.

If the machine is completely dedicated to this database, under what
conditions would the kernel make such decisions? Where can I find more
information on this? Are there other users with similar requirements?

Thanks for your reply.

-Xavier

At 06:08 PM 4/22/01 -0400, Tom Lane wrote:
>xbdelacour@yahoo.com writes:
> > Hi everyone, I'm more or less new to PostgreSQL and am trying to setup a
> > rather large database for a data analysis application. Data is collected
> > and dropped into a single table, which will become ~20GB. Analysis happens
> > on a Windows client (over a network) that queries the data in chunks
> across
> > parallel connections. I'm running the DB on a dual gig p3 w/ 512 memory
> > under Redhat 6 (.0 I think).
>
> > I am setting 'echo 402653184 >/proc/sys/kernel/shmmax', which is being
> > reflected in top. I also specify '-B 48000' when starting postmaster.
>
>Hm.  384M shared memory request on a 512M machine.  I'll bet that the
>kernel is deciding you don't need all that stuff in RAM, and is swapping
>out chunks of the shared memory region to make room for processes and
>its own disk buffering activity.  Try a more reasonable -B setting, like
>maybe a quarter of your physical RAM, max.  There's no percentage in -B
>large enough to risk getting swapped.  Moreover, any physical RAM that
>does happen to be free will be exploited by the kernel for disk
>buffering at its level, so you aren't really saving any I/O by
>increasing Postgres' internal buffering.
>
>BTW, what Postgres version are you using?
>
>                         regards, tom lane
>
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