From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Kevin Brown <blargity@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Simple Join
Date: Sat, 17 Dec 2005 09:56:49 -0500 (EST)
Message-ID: <200512171456.jBHEunM07437@candle.pha.pa.us> (raw)
In-Reply-To: <7484.1134600423@sss.pgh.pa.us>
Tom Lane wrote:
> Kevin Brown <blargity@gmail.com> writes:
> > I'm running 8.1 installed from source on a Debian Sarge server. I have a
> > simple query that I believe I've placed the indexes correctly for, and I
> > still end up with a seq scan. It makes sense, kinda, but it should be able
> > to use the index to gather the right values.
>
> I continue to marvel at how many people think that if it's not using an
> index it must ipso facto be a bad plan ...
>
> That plan looks perfectly fine to me. You could try forcing some other
> choices by fooling with the planner enable switches (eg set
> enable_seqscan = off) but I doubt you'll find much improvement. There
> are too many rows being pulled from ordered_products to make an index
> nestloop a good idea.
We do have an FAQ item:
4.6) Why are my queries slow? Why don't they use my indexes?
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
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To: pgsql-performance@postgresql.org
Cc: pgman@candle.pha.pa.us, tgl@sss.pgh.pa.us, blargity@gmail.com
Subject: Re: Simple Join
In-Reply-To: <200512171456.jBHEunM07437@candle.pha.pa.us>
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