mirror of https://github.com/postgres/postgres
Add to qsort TODO.detail.
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Bruce Momjian
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97ae541cf4
commit
ef524d1775
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@ -2456,3 +2456,171 @@ those comparisons.
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TIP 5: don't forget to increase your free space map settings
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From pgsql-hackers-owner+M81282@postgresql.org Tue Mar 21 14:09:22 2006
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Tue, 21 Mar 2006 15:08:41 -0500 (EST)
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To: Gary Doades <gpd@gpdnet.co.uk>
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cc: pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org
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Subject: Re: [HACKERS] qsort again (was Re: [PERFORM] Strange Create Index behaviour)
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In-Reply-To: <20781.1140046109@sss.pgh.pa.us>
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References: <43F38867.6010701@gpdnet.co.uk> <19510.1140036968@sss.pgh.pa.us> <19779.1140038874@sss.pgh.pa.us> <43F39E53.1020009@gpdnet.co.uk> <20781.1140046109@sss.pgh.pa.us>
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Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
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message dated "Wed, 15 Feb 2006 18:28:29 -0500"
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Date: Tue, 21 Mar 2006 15:08:40 -0500
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Message-ID: <19570.1142971720@sss.pgh.pa.us>
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From: Tom Lane <tgl@sss.pgh.pa.us>
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Status: OR
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Last month I wrote:
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> It seems clear that our qsort.c is doing a pretty awful job of picking
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> qsort pivots, while glibc is mostly managing not to make that mistake.
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I re-ran Gary's test script using the just-committed improvements to
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qsort.c, and got pretty nice numbers (attached --- compare to
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http://archives.postgresql.org/pgsql-performance/2006-02/msg00227.php).
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So it was wrong to blame his problems on the pivot selection --- the
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culprit was that ill-considered switch to insertion sort.
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regards, tom lane
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100 runtimes for latest port/qsort.c, sorted ascending:
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Time: 335.481 ms
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Time: 335.606 ms
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Time: 335.932 ms
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Time: 1727.085 ms
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---------------------------(end of broadcast)---------------------------
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TIP 3: Have you checked our extensive FAQ?
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