Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id 6188E6335CF for ; Fri, 20 Mar 2009 12:55:55 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.208.211]) (amavisd-maia, port 10024) with ESMTP id 09308-07 for ; Fri, 20 Mar 2009 12:55:52 -0300 (ADT) 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 361B963297E for ; Fri, 20 Mar 2009 12:55:51 -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 n2KFtjr5014218; Fri, 20 Mar 2009 11:55:45 -0400 (EDT) To: Matthew Wakeling cc: Scott Carey , Simon Riggs , "pgsql-performance@postgresql.org" Subject: Re: Proposal of tunable fix for scalability of 8.4 In-reply-to: References: <603c8f070903121829r31cf1472ha9876e5c480a542e@mail.gmail.com> <12292.1236964604@sss.pgh.pa.us> <49BB699D.1070809@enterprisedb.com> , <1237362833.3953.186.camel@ebony.2ndQuadrant> Comments: In-reply-to Matthew Wakeling message dated "Fri, 20 Mar 2009 15:28:44 -0000" Date: Fri, 20 Mar 2009 11:55:45 -0400 Message-ID: <14217.1237564545@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.011 tagged_above=0 required=5 tests=AWL=0.011 X-Spam-Level: X-Archive-Number: 200903/291 X-Sequence-Number: 33213 Matthew Wakeling writes: > As for ProcArrayLock, it sounds like it is very much a special case. Quite. Read the section "Interlocking Transaction Begin, Transaction End, and Snapshots" in src/backend/access/transam/README before proposing any changes in this area --- it's a lot more delicate than one might think. We'd have partitioned the ProcArray long ago if it wouldn't have broken the transaction system. regards, tom lane