From: Carlo Stonebanks <stonec.register@sympatico.ca>
To: pgsql-performance@postgresql.org
Subject: How planner decides left-anchored LIKE can use index
Date: Thu, 6 Sep 2007 20:06:44 -0400
Message-ID: <fbq4md$3056$1@news.hub.org> (raw)
Exactly when does the planner decide that a left-anchored like can use the
index?
I have replaced a WHEN lower(last_name) = 'smith'
with WHEN lower(last_name) like 'smith%'
There is an index on lower(last_name). I have seen the planner convert the
LIKE to lower(last_name) >= 'smith' and lower(last_name) < 'smiti' on 8.2.4
systems, but a slow sequence scan and filter on 8.1.9 - is this related to
the version difference (8.1.9 vs 8.2.4) or is this related to something like
operators/classes that have been installed?
Carlo
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To: pgsql-performance@postgresql.org
Cc: stonec.register@sympatico.ca
Subject: Re: How planner decides left-anchored LIKE can use index
In-Reply-To: <fbq4md$3056$1@news.hub.org>
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