X-Original-To: pgsql-hackers-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [200.46.204.2]) by svr1.postgresql.org (Postfix) with ESMTP id EB0A6D1B8A3 for ; Thu, 5 Feb 2004 16:22:37 +0000 (GMT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) with ESMTP id 59450-07 for ; Thu, 5 Feb 2004 12:22:21 -0400 (AST) Received: from sss.pgh.pa.us (unknown [192.204.191.242]) by svr1.postgresql.org (Postfix) with ESMTP id 86208D1B4B7 for ; Thu, 5 Feb 2004 12:22:20 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.12.11/8.12.11) with ESMTP id i15GM0VA003594; Thu, 5 Feb 2004 11:22:00 -0500 (EST) To: shridhar@frodo.hserus.net Cc: "PostgreSQL-development" Subject: Re: [pgsql-hackers-win32] Sync vs. fsync during checkpoint In-reply-to: <200402052045.48448.shridhar@frodo.hserus.net> References: <46C15C39FEB2C44BA555E356FBCD6FA49620A3@m0114.s-mxs.net> <2297.1075992889@sss.pgh.pa.us> <200402052045.48448.shridhar@frodo.hserus.net> Comments: In-reply-to Shridhar Daithankar message dated "Thu, 05 Feb 2004 20:45:48 +0530" Date: Thu, 05 Feb 2004 11:22:00 -0500 Message-ID: <3593.1075998120@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: by amavisd-new at postgresql.org X-Archive-Number: 200402/191 X-Sequence-Number: 49780 Shridhar Daithankar writes: > There are other benefits of writing pages earlier even though they might not > get synced immediately. Such as? > It would tell kernel that this is latest copy of updated buffer. Kernel VFS > should make that copy visible to every other backend as well. The buffer > manager will fetch the updated copy from VFS cache next time. All without > going to disk actually..(Within the 30 seconds window of course..) This seems quite irrelevant given the way we handle shared buffers. > frequent fsyncs or frequent fsyncs per file descriptor written? I thought it > was later. You can only fsync one FD at a time (too bad ... if there were a multi-file-fsync API it'd solve the overspecified-write-ordering issue). regards, tom lane