Re: postgres 7.4 vs 8.x redux: query plans

Ok, well, I dropped the DB and reloaded it and now all seems to be
fine and performing well. I'm not sure what was going on before.
Thanks for everyone's help!

Alex

On 4/3/07, Alex Deucher <alexdeucher(at)gmail(dot)com> wrote:
> On 4/3/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > "Alex Deucher" <alexdeucher(at)gmail(dot)com> writes:
> > > Turning off bitmapscan ends up doing a sequential scan. Turning off
> > > both bitmapscan and seqscan results in a bitmap heap scan. It doesn't
> > > seem to want to use the index at all. Any ideas?
> >
> > The "ORed indexscans" plan style that was in 7.4 isn't there anymore;
> > we use bitmap OR'ing instead. There actually are repeated indexscans
> > hidden under the "= ANY" indexscan condition in 8.2, it's just that
> > the mechanism for detecting duplicate matches is different. AFAIK the
> > index access costs ought to be about the same either way, and the other
> > costs the same or better as what we did in 7.4. It's clear though that
> > 8.2 is taking some kind of big hit in the index access in your case.
> > There's something very strange going on here.
> >
> > You do have both lc_collate and lc_ctype set to C, right? What about
> > database encoding?
> >
>
> hmmm... ok, this is weird. performance seems to have improved
> significantly after I reloaded postgres after adding some hew hosts to
> the pg_hba.conf. I'll run some more tests and let you know what
> happens.
>
> Alex
>