X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [64.117.224.130]) by svr1.postgresql.org (Postfix) with ESMTP id C7B96D1C4D5 for ; Thu, 14 Aug 2003 18:57:02 +0000 (GMT) Received: from svr1.postgresql.org ([64.117.224.193]) by localhost (neptune.hub.org [64.117.224.130]) (amavisd-new, port 10024) with ESMTP id 34304-07 for ; Thu, 14 Aug 2003 15:56:53 -0300 (ADT) Received: from smtp101.mail.sc5.yahoo.com (smtp101.mail.sc5.yahoo.com [216.136.174.139]) by svr1.postgresql.org (Postfix) with SMTP id C74F6D1C9BE for ; Thu, 14 Aug 2003 15:56:50 -0300 (ADT) Received: from pcp01341166pcs.wilog301.pa.comcast.net (HELO europa.janwieck.net) (janwieck@68.80.245.191 with login) by smtp.mail.vip.sc5.yahoo.com with SMTP; 14 Aug 2003 18:56:51 -0000 Received: from Yahoo.com (ismtp.afilias.com [216.217.55.254]) (authenticated) by europa.janwieck.net (8.11.6/8.11.6) with ESMTP id h7EIusH14569; Thu, 14 Aug 2003 14:56:54 -0400 Message-ID: <3F3BDB2A.40506@Yahoo.com> Date: Thu, 14 Aug 2003 14:55:38 -0400 From: Jan Wieck Organization: Unorganized User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Tom Lane Cc: Scott Cain , PgSQL Performance ML , pgsql-sql@postgresql.org Subject: Re: [SQL] EXTERNAL storage and substring on long strings References: <1059679600.1429.41.camel@localhost.localdomain> <3F297CBA.1080703@joeconway.com> <1059686498.7505.558.camel@haggis> <1060010735.1433.26.camel@localhost.localdomain> <3574.1060012423@sss.pgh.pa.us> <3F3BA49D.9070405@Yahoo.com> <6311.1060884021@sss.pgh.pa.us> In-Reply-To: <6311.1060884021@sss.pgh.pa.us> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at postgresql.org X-Archive-Number: 200308/267 X-Sequence-Number: 3083 Tom Lane wrote: > Jan Wieck writes: >> Doesn't look that unrealistic to me. A plain text based substring >> function will reassemble the whole beast first before cutting out the >> wanted part. His manually chunked version will read only those chunks >> needed. > > So does substr(), if applied to EXTERNAL (non-compressed) toasted text. > See John Gray's improvements a release or two back. Duh ... of course, EXTERNAL is uncompressed ... where do I have my head? Jan -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck@Yahoo.com #