From: Leonardo Francalanci <m_lists@yahoo.it>
To: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <peter@2ndquadrant.com>
Cc: Stefan Keller <sfkeller@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Hash index use presently(?) discouraged since 2005: revive or bury it?
Date: Wed, 14 Sep 2011 10:43:27 +0100 (BST)
Message-ID: <1315993407.43414.YahooMailNeo@web29009.mail.ird.yahoo.com> (raw)
In-Reply-To: <16096.1315959870@sss.pgh.pa.us>
References: <CAFcOn293Rzi7cZYWBT8tjxCtNX5pYdbknANXgf9mWfBizK8Frg@mail.gmail.com>
<CAEYLb_Udue8_XSE9K0KMqKBE_62yurv1bY4Wc+qJoGykZ_rXtA@mail.gmail.com>
<16096.1315959870@sss.pgh.pa.us>
>> Hash indexes have been improved since 2005 - their performance was
>> improved quite a bit in 9.0. Here's a more recent analysis:
>
>> http://www.depesz.com/index.php/2010/06/28/should-you-use-hash-index/
>
> The big picture though is that we're not going to remove hash indexes,
> even if they're nearly useless in themselves
Well, if they provide 3x the performance of btree indexes on index creation,
I wouldn't call them "useless" just because they're not logged or they can't
be unique. In fact, I think the docs should specify that in index creation
they're actually better than btree (if, in fact, they are and the "depesz" test
is not a corner case).
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To: pgsql-performance@postgresql.org
Cc: m_lists@yahoo.it, tgl@sss.pgh.pa.us, peter@2ndquadrant.com, sfkeller@gmail.com
Subject: Re: Hash index use presently(?) discouraged since 2005: revive or bury it?
In-Reply-To: <1315993407.43414.YahooMailNeo@web29009.mail.ird.yahoo.com>
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