From: Richard Huxton <dev@archonet.com>
To: dmitry potapov <potapov.dmitry@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: "WHERE 1 = 2 OR ..." makes planner choose a very inefficient plan
Date: Thu, 18 Apr 2013 15:43:20 +0100
Message-ID: <51700688.4050505@archonet.com> (raw)
In-Reply-To: <CAJPZb_vmf3dkCv0Rre+VOm6bkJc3hugjEE2h0bgY1WqduDLUbg@mail.gmail.com>
References: <CAJPZb_vmf3dkCv0Rre+VOm6bkJc3hugjEE2h0bgY1WqduDLUbg@mail.gmail.com>
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On 18/04/13 15:20, dmitry potapov wrote:
> Hello,
>
> I recently stumbled upon on what could be a planner bug or a corner
> case. If "<false condition> OR ..." is added to WHERE clause of SELECT
> query, then the planner chooses a very inefficient plan. Consider a query:
> If I comment out "1=2 OR", then the plan changes dramatically:
What happens if you substitute:
1. 1=3 OR
2. false OR
--
Richard Huxton
Archonet Ltd
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To: pgsql-performance@postgresql.org
Cc: dev@archonet.com, potapov.dmitry@gmail.com
Subject: Re: "WHERE 1 = 2 OR ..." makes planner choose a very inefficient plan
In-Reply-To: <51700688.4050505@archonet.com>
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