X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 33C02D9743 for ; Thu, 6 Oct 2005 16:57:49 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 03629-01 for ; Thu, 6 Oct 2005 19:57:45 +0000 (GMT) Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by svr1.postgresql.org (Postfix) with ESMTP id E3C2EDA41E for ; Thu, 6 Oct 2005 16:57:45 -0300 (ADT) 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 j96Jvc0d025131; Thu, 6 Oct 2005 15:57:38 -0400 (EDT) To: Martijn van Oosterhout Cc: Ron Peacetree , "Jonah H. Harris" , pgsql-hackers@postgresql.org, pgsql-performance@postgresql.org Subject: Re: [HACKERS] A Better External Sort? In-reply-to: <20051006165725.GF10127@svana.org> References: <138872.1128556455518.JavaMail.root@elwamui-milano.atl.sa.earthlink.net> <20051006165725.GF10127@svana.org> Comments: In-reply-to Martijn van Oosterhout message dated "Thu, 06 Oct 2005 18:57:30 +0200" Date: Thu, 06 Oct 2005 15:57:38 -0400 Message-ID: <25130.1128628658@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.006 required=5 tests=[AWL=0.006] X-Spam-Level: X-Archive-Number: 200510/128 X-Sequence-Number: 14896 Martijn van Oosterhout writes: > Indeed, one of the things on my list is to remove all the lseeks in > favour of pread. Halving the number of kernel calls has got to be worth > something right? Portability is an issue ofcourse... Being sure that it's not a pessimization is another issue. I note that glibc will emulate these functions if the kernel doesn't have them; which means you could be replacing one kernel call with three. And I don't think autoconf has any way to determine whether a libc function represents a native kernel call or not ... regards, tom lane