Received: from localhost (unknown [200.46.204.184]) by developer.postgresql.org (Postfix) with ESMTP id 449C62E0051 for ; Tue, 29 Apr 2008 10:48:41 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 04318-02 for ; Tue, 29 Apr 2008 10:48:29 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from oxford.xeocode.com (unknown [62.232.55.118]) by developer.postgresql.org (Postfix) with ESMTP id 5E0EE2E0041 for ; Tue, 29 Apr 2008 10:48:37 -0300 (ADT) Received: from localhost ([127.0.0.1] helo=oxford.xeocode.com) by oxford.xeocode.com with esmtp (Exim 4.69) (envelope-from ) id 1JqqC7-0004vf-Vo; Tue, 29 Apr 2008 09:48:32 -0400 To: "Pavan Deolasee" Cc: "Gauri Kanekar" , "Greg Smith" , Subject: Re: Replication Syatem In-Reply-To: <2e78013d0804290425n402f5e94i90bc7206aeefffdc@mail.gmail.com> (Pavan Deolasee's message of "Tue\, 29 Apr 2008 16\:55\:38 +0530") User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) X-Draft-From: ("nnimap+mail01.enterprisedb.com:INBOX.performance" 5414) References: <7e4ba9550804280638ie81dc23w472785c83cd38fcf@mail.gmail.com> <7e4ba9550804280705q43c51e66l104a5ff9272bbd4d@mail.gmail.com> <20080428162243.GN2970@commandprompt.com> <7e4ba9550804282246p73c62fc6y5e7cb7dda55a6b50@mail.gmail.com> <7e4ba9550804290405i4c0d3a57x1640239c9995c13@mail.gmail.com> <2e78013d0804290425n402f5e94i90bc7206aeefffdc@mail.gmail.com> From: Gregory Stark Organization: EnterpriseDB Date: Tue, 29 Apr 2008 09:48:31 -0400 Message-ID: <87lk2w4vrk.fsf@oxford.xeocode.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.121 tagged_above=0 required=5 tests=AWL=-1.878, FS_REPLICA=1.179, RDNS_NONE=0.1, SARE_SPEC_REPLICA=0.72 X-Spam-Level: X-Archive-Number: 200804/440 X-Sequence-Number: 29933 "Pavan Deolasee" writes: >> Any special guideline to follow to make HOT working?? >> > > You can do couple of things to benefit from HOT. > > 1. HOT addresses a special, but common case where UPDATE operation > does not change any of the index keys. So check if your UPDATE changes > any of the index keys. If so, see if you can avoid having index > involving that column. Of course, I won't advocate dropping an index > if it would drastically impact your frequently run queries. > > 2. You may leave some free space in the heap (fillfactor less than > 100). My recommendation would be to leave space worth of one row or > slightly more than that to let first UPDATE be an HOT update. > Subsequent UPDATEs in the page may reuse the dead row created by > earlier UPDATEs. > > 3. Avoid any long running transactions. Perhaps we should put this list in the FAQ. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's 24x7 Postgres support!