Re: Bitmapscan changes

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
Cc: Patches <pgsql-patches(at)postgresql(dot)org>, Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>
Subject: Re: Bitmapscan changes
Date: 2007-03-12 14:36:50
Message-ID: 15358.1173710210@sss.pgh.pa.us
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Heikki Linnakangas <heikki(at)enterprisedb(dot)com> writes:
> The patch also adds support for candidate matches. An index scan can
> indicate that the tuples it's returning are candidates, and the executor
> will recheck the original scan quals of any candidate matches when the
> tuple is fetched from heap.

This will not work, unless we change the planner --- the original quals
aren't necessarily there in some corner cases (partial indexes, if
memory serves).

> The motivation for adding the support for candidate matches is that GIT
> / clustered indexes need it.

You need more than a vague reference to an unapplied patch to convince
me we ought to do this.

regards, tom lane

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