From: | Gregory Stark <stark(at)enterprisedb(dot)com> |
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To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | "Simon Riggs" <simon(at)2ndquadrant(dot)com>, "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com>, "Patches" <pgsql-patches(at)postgresql(dot)org> |
Subject: | Re: A little COPY speedup |
Date: | 2007-03-02 16:25:53 |
Message-ID: | 87ejo7r4ry.fsf@stark.xeocode.com |
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Lists: | pgsql-patches |
"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> "Simon Riggs" <simon(at)2ndquadrant(dot)com> writes:
>> I'm slightly worried though since that seems to have changed from 8.2,
>> which I oprofiled over Christmas.
>
> If you were testing a case with wider rows than Heikki tested, you'd see
> less impact --- the cost of the old way was O(N^2) in the number of
> tuples that fit on a page, so the behavior gets rapidly worse as you get
> down to smaller tuple sizes. (Come to think of it, the cmin/cmax
> collapse would be a factor here too.)
Or larger block sizes of course. A 32kb block would be 16x as bad which starts
to be pretty serious.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
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