X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id F422A9DCC49 for ; Tue, 28 Feb 2006 19:45:14 -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 44754-02 for ; Tue, 28 Feb 2006 19:45:17 -0400 (AST) 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 2A8889DCB82 for ; Tue, 28 Feb 2006 19:45:10 -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 k1SNj6i6003868; Tue, 28 Feb 2006 18:45:06 -0500 (EST) To: PFC cc: "Bruce Momjian" , "Javier Somoza" , "Evgeny Gridasov" , pgsql-performance@postgresql.org Subject: Re: wal sync method In-reply-to: References: <200602280114.k1S1EAQ17159@candle.pha.pa.us> Comments: In-reply-to PFC message dated "Wed, 01 Mar 2006 00:31:33 +0100" Date: Tue, 28 Feb 2006 18:45:06 -0500 Message-ID: <3867.1141170306@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.111 required=5 tests=[AWL=0.111] X-Spam-Score: 0.111 X-Spam-Level: X-Archive-Number: 200602/447 X-Sequence-Number: 17433 PFC writes: > Just a stupid question about the various fsync settings. > There is fsync=off, but is there fsync=fflush ? > fflush would mean only an OS crash could cause data loss, > I think.it could be useful for some applications where you need a speed > boost (like testing database import scripts...) without being as scary as > fsync=off... I think you misunderstand. There aren't any scenarios where a PG crash (without hardware/OS crash) risks data, because we always at least write() data before commit. The only issue is how hard do we try to get the OS+hardware to push that data down to disk. regards, tom lane