From: Tom Lane <tgl@sss.pgh.pa.us>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
To: Markus Bertheau <mbertheau.pg@googlemail.com>
To: Joshua D. Drake <jd@commandprompt.com>
To: Peter Koczan <pjkoczan@gmail.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
To: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: disabling an index without deleting it?
Date: Wed, 27 Feb 2008 18:33:01 -0500
Message-ID: <12278.1204155181@sss.pgh.pa.us> (raw)
In-Reply-To: <10385.1204153217@sss.pgh.pa.us>
References: <4544e0330802261246t574167fdpc47629d1bbe64fed@mail.gmail.com>
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<20080226130339.64bd4ec3@commandprompt.com>
<9050.1204064560@sss.pgh.pa.us>
<684362e10802261848j79686752k6dfbe032e985b131@mail.gmail.com>
<684362e10802261848j79686752k6dfbe032e985b131@mail.gmail.com>
<13604.1204087729@sss.pgh.pa.us>
<47C578A1.EE98.0025.0@wicourts.gov>
<10385.1204153217@sss.pgh.pa.us>
I wrote:
> In the particular case at hand, a planner hook to make it ignore the
> index is a far better solution anyway...
Just as proof of concept, a quick-and-dirty version of this is attached.
It works in 8.3 and up. Sample (after compiling the .so):
regression=# load '/home/tgl/pgsql/planignoreindex.so';
LOAD
regression=# explain select * from tenk1 where unique1 = 42;
QUERY PLAN
-----------------------------------------------------------------------------
Index Scan using tenk1_unique1 on tenk1 (cost=0.00..8.27 rows=1 width=244)
Index Cond: (unique1 = 42)
(2 rows)
regression=# set ignore_index TO 'tenk1_unique1';
SET
regression=# explain select * from tenk1 where unique1 = 42;
QUERY PLAN
---------------------------------------------------------
Seq Scan on tenk1 (cost=0.00..483.00 rows=1 width=244)
Filter: (unique1 = 42)
(2 rows)
regression=#
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, Kevin.Grittner@wicourts.gov, mbertheau.pg@googlemail.com, jd@commandprompt.com, pjkoczan@gmail.com, scott.marlowe@gmail.com
Subject: Re: disabling an index without deleting it?
In-Reply-To: <12278.1204155181@sss.pgh.pa.us>
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