Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 82C5F2E0038 for ; Mon, 18 Feb 2008 06:33:54 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 75635-04 for ; Mon, 18 Feb 2008 06:33:44 -0400 (AST) Received: from oxford.xeocode.com (unknown [62.232.55.118]) by postgresql.org (Postfix) with ESMTP id D7B0C2E002F for ; Mon, 18 Feb 2008 06:33:49 -0400 (AST) Received: from localhost ([127.0.0.1] helo=oxford.xeocode.com) by oxford.xeocode.com with esmtp (Exim 4.69) (envelope-from ) id 1JR3Ja-0001DK-Rh; Mon, 18 Feb 2008 10:33:38 +0000 To: "Tom Lane" Cc: , "Jan Wieck" Subject: Re: Proposed patch to change TOAST compression strategy In-Reply-To: <26048.1203271939@sss.pgh.pa.us> (Tom Lane's message of "Sun\, 17 Feb 2008 13\:12\:19 -0500") User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) X-Draft-From: ("nnimap+mail01.enterprisedb.com:INBOX" 64817) References: <26048.1203271939@sss.pgh.pa.us> From: Gregory Stark Organization: EnterpriseDB Date: Mon, 18 Feb 2008 10:33:38 +0000 Message-ID: <87ir0mo8ot.fsf@oxford.xeocode.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200802/56 X-Sequence-Number: 4908 "Tom Lane" writes: > * Adds an early-failure path to the compressor as suggested by Jan: > if it's been unable to find even one compressible substring in the > first 1KB (parameterizable), assume we're looking at incompressible > input and give up. (There are various ways this could be done, but > this way seems to add the least overhead to the compressor's inner > loop.) I'm not sure how to test the rest of it, but this bit seems testable. I fear this may be too conservative. Even nigh incompressible data will find a few backreferences. I'll try some tests and see. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's On-Demand Production Tuning