diff --git a/doc/TODO.detail/qsort b/doc/TODO.detail/qsort index e7833d01ffcefb2a400f7085cdb3de8b715c4c9e..5dfe921ad7c31321166292dd14bf24962dcb0118 100644 --- a/doc/TODO.detail/qsort +++ b/doc/TODO.detail/qsort @@ -2456,3 +2456,171 @@ those comparisons. ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings +From pgsql-hackers-owner+M81282@postgresql.org Tue Mar 21 14:09:22 2006 +Return-path: <pgsql-hackers-owner+M81282@postgresql.org> +Received: from ams.hub.org (ams.hub.org [200.46.204.13]) + by candle.pha.pa.us (8.11.6/8.11.6) with ESMTP id k2LK9KM11902 + for <pgman@candle.pha.pa.us>; Tue, 21 Mar 2006 15:09:21 -0500 (EST) +Received: from postgresql.org (postgresql.org [200.46.204.71]) + by ams.hub.org (Postfix) with ESMTP id 6B1CF67BBF6; + Tue, 21 Mar 2006 16:09:18 -0400 (AST) +X-Original-To: pgsql-hackers-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 0B2E19DCA0F; + Tue, 21 Mar 2006 16:08:50 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54998-02; Tue, 21 Mar 2006 16:08:50 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by postgresql.org (Postfix) with ESMTP id C39619DC9E6; + Tue, 21 Mar 2006 16:08:45 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id k2LK8flq019571; + Tue, 21 Mar 2006 15:08:41 -0500 (EST) +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) +In-Reply-To: <20781.1140046109@sss.pgh.pa.us> +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> +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> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.113 required=5 tests=[AWL=0.113] +X-Spam-Score: 0.113 +X-Mailing-List: pgsql-hackers +List-Archive: <http://archives.postgresql.org/pgsql-hackers> +List-Help: <mailto:majordomo@postgresql.org?body=help> +List-Id: <pgsql-hackers.postgresql.org> +List-Owner: <mailto:pgsql-hackers-owner@postgresql.org> +List-Post: <mailto:pgsql-hackers@postgresql.org> +List-Subscribe: <mailto:majordomo@postgresql.org?body=sub%20pgsql-hackers> +List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-hackers> +Precedence: bulk +Sender: pgsql-hackers-owner@postgresql.org +Status: OR + +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 +Time: 342.213 ms +Time: 342.452 ms +Time: 342.515 ms +Time: 342.540 ms +Time: 342.928 ms +Time: 343.548 ms +Time: 343.663 ms +Time: 344.192 ms +Time: 344.952 ms +Time: 345.152 ms +Time: 345.174 ms +Time: 345.444 ms +Time: 346.848 ms +Time: 348.144 ms +Time: 348.842 ms +Time: 354.550 ms +Time: 356.877 ms +Time: 357.475 ms +Time: 358.487 ms +Time: 364.178 ms +Time: 370.730 ms +Time: 493.098 ms +Time: 648.009 ms +Time: 849.345 ms +Time: 860.616 ms +Time: 936.800 ms +Time: 1727.085 ms + +---------------------------(end of broadcast)--------------------------- +TIP 3: Have you checked our extensive FAQ? + + http://www.postgresql.org/docs/faq +