From: Tom Lane <tgl@sss.pgh.pa.us>
To: scott.marlowe <scott.marlowe@ihs.com>
Cc: Stephan Szabo <sszabo@megazone.bigpanda.com>
Cc: brad-pgperf@duttonbros.com
Cc: pgsql-performance@postgresql.org
Subject: Re: index usage
Date: Wed, 28 Apr 2004 12:41:40 -0400
Message-ID: <424.1083170500@sss.pgh.pa.us> (raw)
In-Reply-To: <Pine.LNX.4.33.0404280935510.6453-100000@css120.ihs.com>
References: <Pine.LNX.4.33.0404280935510.6453-100000@css120.ihs.com>
"scott.marlowe" <scott.marlowe@ihs.com> writes:
> There are tons of hints that it works this way in how they're written, but
> nothing that just comes out and says that with pgsql's mvcc
> implementation, an index scan still has to hit the pages that contain the
> tuples, so often in pgsql a seq scan is a win where in other databases and
> index scan would have been a win?
> If not, where would I add it if I were going to write something up for the
> docs? Just wondering...
AFAIR the only place in the docs that mentions seqscan or indexscan at
all is the discussion of EXPLAIN in "Performance Tips". Perhaps a
suitably-enlarged version of that section could cover this.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, scott.marlowe@ihs.com, sszabo@megazone.bigpanda.com, brad-pgperf@duttonbros.com
Subject: Re: index usage
In-Reply-To: <424.1083170500@sss.pgh.pa.us>
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