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Re: Merge join performance

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-hackers(at)postgresql(dot)org, Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Merge join performance
Date: 2006-08-24 01:22:39
Message-ID: 27586.1156382559@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Heikki Linnakangas <heikki(at)enterprisedb(dot)com> writes:
> We can make markpos fast, if we make the copy lazily in _bt_steppage, 

Nice hack.  Getting rid of the buffer refcount manipulations is probably
even more useful than avoiding the memcpy.

> I did some micro-benchmarking of merge join performance, see attached 
> test. Test results, on my laptop:

> 8_1_STABLE: 1.77 s
> HEAD, with patch: 1.65 s
> HEAD, without patch: 2.46 s

Hm, I don't see a performance regression on my machine, but there is a
measureable improvement with the patch:

8.1 branch:	10.6 s
CVS HEAD:	10.1 s
w/patch:	 9.3 s

Patch applied ...

			regards, tom lane

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