From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)svr1(dot)postgresql(dot)org> |
Cc: | pgsql-committers(at)postgresql(dot)org |
Subject: | Re: pgsql-server/src/backend/utils/sort tuplesort.c |
Date: | 2004-03-17 22:31:56 |
Message-ID: | 200403172231.i2HMVun00293@candle.pha.pa.us |
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Lists: | pgsql-committers |
Tom Lane wrote:
> CVSROOT: /cvsroot
> Module name: pgsql-server
> Changes by: tgl(at)svr1(dot)postgresql(dot)org 04/03/17 18:24:58
>
> Modified files:
> src/backend/utils/sort: tuplesort.c
>
> Log message:
> During btree index build, sort equal-keyed tuples according to their
> TID (heap position). This doesn't do anything to the validity of the
> finished index, but by pretending to qsort() that there are no really
> equal keys in the sort, we can avoid performance problems with qsort
> implementations that have trouble with large numbers of equal keys.
> Patch from Manfred Koizar.
I think there is also the advantage that many equal keys will access the
heap in a more sequential, rather than random, order, which is the part
that really excited me.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
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