Re: Worsening performance with 7.4 on flash-based system

On 4/29/06, Greg Stumph <gregstumph(at)comcast(dot)net> wrote:
> Well, since I got no response at all to this message, I can only assume that
> I've asked the question in an insufficient way, or else that no one has
> anything to offer on our problem.
>
> This was my first post to the list, so if there's a better way I should be
> asking this, or different data I should provide, hopefully someone will let
> me know...
>
> Thanks,
> Greg
>
> "Greg Stumph" <gregstumph(at)comcast(dot)net> wrote in message
> news:e2b80f$245o$1(at)news(dot)hub(dot)org(dot)(dot)(dot)
> > We are experiencing gradually worsening performance in PostgreSQL 7.4.7,
> > on a system with the following specs:
> > Linux OS (Fedora Core 1, 2.4 kernal)
> > Flash file system (2 Gig, about 80% full)
> > 256 Meg RAM
> > 566 MHz Celeron CPU
> >
> > We use Orbit 2.9.8 to access PostGres. The database contains 62 tables.
> >
> > When the system is running with a fresh copy of the database, performance
> > is fine. At its worst, we are seeing fairly simple SELECT queries taking
> > up to 1 second to execute. When these queries are run in a loop, the loop
> > can take up to 30 seconds to execute, instead of the 2 seconds or so that
> > we would expect.

If you're inserting/updating/deleting a table or tables heavily, then
you'll need to vacuum it a lot more often than a reasonably static
table. Are you running contrib/autovacuum at all? PG 8.0 and above
have autovacuum built in but 7.4.x needs to run the contrib version.

PS - the latest 7.4 version is .12 - see
http://www.postgresql.org/docs/7.4/interactive/release.html for what
has changed (won't be much in performance terms but may fix data-loss
bugs).

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