Re: Hash index use presently(?) discouraged since 2005: revive or bury it?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Merlin Moncure <mmoncure(at)gmail(dot)com>
Cc: Claudio Freire <klaussfreire(at)gmail(dot)com>, Robert Klemme <shortcutter(at)googlemail(dot)com>, Stefan Keller <sfkeller(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Peter Geoghegan <peter(at)2ndquadrant(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Hash index use presently(?) discouraged since 2005: revive or bury it?
Date: 2011-09-20 16:25:19
Message-ID: 9496.1316535919@sss.pgh.pa.us
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Merlin Moncure <mmoncure(at)gmail(dot)com> writes:
> just selects. update test is also very interesting -- the only test I
> did for for updates is 'update foo set x=x+1' which was a win for
> btree (20-30% faster typically). perhaps this isn't algorithm induced
> though -- lack of wal logging could actually hurt time to commit
> because it deserializes i/o.

In 9.1+, you could remove WAL from the comparison by doing the tests on
an unlogged table.

regards, tom lane

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