Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 0F66F1337B34 for ; Tue, 16 Nov 2010 20:51:51 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 38358-09 for ; Wed, 17 Nov 2010 00:51:43 +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 CC75F1335B36 for ; Tue, 16 Nov 2010 20:51:42 -0400 (AST) 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 oAH0pSAK010823; Tue, 16 Nov 2010 19:51:28 -0500 (EST) To: Andres Freund cc: pgsql-performance@postgresql.org, Josh Berkus , Greg Smith Subject: Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1? In-reply-to: <201011170130.10720.andres@anarazel.de> References: <4CE312D9.6030503@agliodbs.com> <9058.1289950294@sss.pgh.pa.us> <201011170130.10720.andres@anarazel.de> Comments: In-reply-to Andres Freund message dated "Wed, 17 Nov 2010 01:30:09 +0100" Date: Tue, 16 Nov 2010 19:51:28 -0500 Message-ID: <10822.1289955088@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-10 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201011/274 X-Sequence-Number: 41298 Andres Freund writes: > On Wednesday 17 November 2010 00:31:34 Tom Lane wrote: >> Well, we're not going to increase the default to gigabytes > Especially not as I don't think it will have any effect after wal_segment_size > as that will force a write-out anyway. Or am I misremembering the > implementation? Well, there's a forced fsync after writing the last page of an xlog file, but I don't believe that proves that more than 16MB of xlog buffers is useless. Other processes could still be busy filling the buffers. regards, tom lane