Re: hash index improving v3

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Xiao Meng <mx(dot)cogito(at)gmail(dot)com>
Cc: pgsql-patches(at)postgresql(dot)org, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>
Subject: Re: hash index improving v3
Date: 2008-09-04 02:06:42
Message-ID: 1220494002.4371.813.camel@ebony.2ndQuadrant
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On Mon, 2008-08-18 at 09:46 +0800, Xiao Meng wrote:
> There's minor change against the previous
> one( ).
> * merge branch master(Aug 16) into the patch
> * clean code and make some comment
> Performance result is here
> It seems hash index is a little better on index creation and
> selection.
> But maybe it's in the range of noise, I'm not sure.
> I'd like to try it with a bigger dataset (e.g. table with 10GB) but
> there is not enough space in my computer.
> Anyone interest can make a test on a bigger data set.

You don't give the text of the query used to do these performance tests,
so I can't validate your test results.

Right now it seems strange that the index is larger than a btree, yet
the performance tests show that 3 times as much I/O was used accessing
the btree.

Simon Riggs
PostgreSQL Training, Services and Support

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