---------------------------(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