From: Tom Lane <tgl@sss.pgh.pa.us>
To: Willy-Bas Loos <willybas@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: not using partial index
Date: Wed, 20 Apr 2011 09:25:57 -0400
Message-ID: <25018.1303305957@sss.pgh.pa.us> (raw)
In-Reply-To: <BANLkTikUt403PkMGb4bFMHMBZsJZRPV5Bw@mail.gmail.com>
References: <BANLkTikUt403PkMGb4bFMHMBZsJZRPV5Bw@mail.gmail.com>
Willy-Bas Loos <willybas@gmail.com> writes:
> [ NOT field1 ISNULL is not seen as equivalent to field1 IS NOT NULL ]
> Any ideas why this might be?
The planner does not spend an infinite number of cycles on trying to
make different expressions look alike.
As it happens, 9.1 does know this equivalence, as a byproduct of
http://git.postgresql.org/gitweb?p=postgresql.git&a=commitdiff&h=220e45bf325b061b8dbd7451f87...
But I don't consider it a bug that older versions don't do it.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, willybas@gmail.com
Subject: Re: not using partial index
In-Reply-To: <25018.1303305957@sss.pgh.pa.us>
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