Re: Bitmap index scans use of filters on available columns

From: Antonin Houska <ah(at)cybertec(dot)at>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Bitmap index scans use of filters on available columns
Date: 2015-11-04 09:12:21
Message-ID: 20734.1446628341@localhost
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While prefix expression

y like 'abc%'

can be converted to

y >= 'abc'

(see expand_indexqual_opclause()), I'm not sure any kind of expansion is
possible for '%abc%' which would result in a b-tree searchable condition.

Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> Is there a fundamental reason the filter on y is not being applied to
> the index scan, rather than the heap scan?

--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at

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