Add to qsort TODO.detail.

doc/TODO.detail/qsort

@@ -2456,3 +2456,171 @@ those comparisons.
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+To: Gary Doades <gpd@gpdnet.co.uk>
+cc: pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org
+Subject: Re: [HACKERS] qsort again (was Re: [PERFORM] Strange Create Index behaviour) 
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+Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
+	message dated "Wed, 15 Feb 2006 18:28:29 -0500"
+Date: Tue, 21 Mar 2006 15:08:40 -0500
+Message-ID: <19570.1142971720@sss.pgh.pa.us>
+From: Tom Lane <tgl@sss.pgh.pa.us>
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+
+Last month I wrote:
+> It seems clear that our qsort.c is doing a pretty awful job of picking
+> qsort pivots, while glibc is mostly managing not to make that mistake.
+
+I re-ran Gary's test script using the just-committed improvements to
+qsort.c, and got pretty nice numbers (attached --- compare to
+http://archives.postgresql.org/pgsql-performance/2006-02/msg00227.php).
+So it was wrong to blame his problems on the pivot selection --- the
+culprit was that ill-considered switch to insertion sort.
+
+			regards, tom lane
+
+100 runtimes for latest port/qsort.c, sorted ascending:
+
+Time: 335.481 ms
+Time: 335.606 ms
+Time: 335.932 ms
+Time: 336.039 ms
+Time: 336.182 ms
+Time: 336.231 ms
+Time: 336.711 ms
+Time: 336.721 ms
+Time: 336.971 ms
+Time: 336.982 ms
+Time: 337.036 ms
+Time: 337.190 ms
+Time: 337.223 ms
+Time: 337.312 ms
+Time: 337.350 ms
+Time: 337.423 ms
+Time: 337.523 ms
+Time: 337.528 ms
+Time: 337.565 ms
+Time: 337.566 ms
+Time: 337.732 ms
+Time: 337.741 ms
+Time: 337.744 ms
+Time: 337.786 ms
+Time: 337.790 ms
+Time: 337.898 ms
+Time: 337.905 ms
+Time: 337.952 ms
+Time: 337.976 ms
+Time: 338.017 ms
+Time: 338.123 ms
+Time: 338.206 ms
+Time: 338.306 ms
+Time: 338.514 ms
+Time: 338.594 ms
+Time: 338.597 ms
+Time: 338.683 ms
+Time: 338.705 ms
+Time: 338.729 ms
+Time: 338.748 ms
+Time: 338.816 ms
+Time: 338.958 ms
+Time: 338.963 ms
+Time: 338.997 ms
+Time: 339.074 ms
+Time: 339.106 ms
+Time: 339.134 ms
+Time: 339.159 ms
+Time: 339.226 ms
+Time: 339.260 ms
+Time: 339.289 ms
+Time: 339.341 ms
+Time: 339.500 ms
+Time: 339.585 ms
+Time: 339.595 ms
+Time: 339.774 ms
+Time: 339.897 ms
+Time: 339.927 ms
+Time: 340.064 ms
+Time: 340.133 ms
+Time: 340.172 ms
+Time: 340.219 ms
+Time: 340.261 ms
+Time: 340.323 ms
+Time: 340.708 ms
+Time: 340.761 ms
+Time: 340.785 ms
+Time: 340.900 ms
+Time: 340.986 ms
+Time: 341.339 ms
+Time: 341.564 ms
+Time: 341.707 ms
+Time: 342.155 ms
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+Time: 342.452 ms
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+Time: 342.540 ms
+Time: 342.928 ms
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+Time: 348.842 ms
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+Time: 356.877 ms
+Time: 357.475 ms
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+Time: 364.178 ms
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+Time: 493.098 ms
+Time: 648.009 ms
+Time: 849.345 ms
+Time: 860.616 ms
+Time: 936.800 ms
+Time: 1727.085 ms
+
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