Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id 89F911336FA7 for ; Thu, 28 Apr 2011 10:25:43 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.29]) (amavisd-maia, port 10024) with ESMTP id 91201-02 for ; Thu, 28 Apr 2011 13:25:38 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id E6EF1133616B for ; Thu, 28 Apr 2011 10:25:35 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id p3SDPX4S025786; Thu, 28 Apr 2011 09:25:33 -0400 (EDT) To: HSIEN-WEN CHU cc: pgsql-hackers@postgresql.org Subject: Re: VX_CONCURRENT flag on vxfs( 5.1 or later) for performance for postgresql? In-reply-to: References: Comments: In-reply-to HSIEN-WEN CHU message dated "Thu, 28 Apr 2011 11:33:44 +0800" Date: Thu, 28 Apr 2011 09:25:33 -0400 Message-ID: <25785.1303997133@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-5 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201104/1722 X-Sequence-Number: 186924 HSIEN-WEN CHU writes: > When database files are on a VxFS filesystem, performance can be > significantly improved by setting the VX_CONCURRENT cache advisory on > the file according to vxfs document, Presumably, if whatever behavior this invokes were an unalloyed good, they'd have just made it the default. The existence of a flag makes me suppose that there are some clear application-visible downsides. What are they? BTW, please do not cross-post the same question to three different lists. regards, tom lane