Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 35BA1B5DC23 for ; Thu, 15 Sep 2011 19:38:21 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 00903-06 for ; Thu, 15 Sep 2011 22:38:15 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0-rc2 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id D0EB7B5DC16 for ; Thu, 15 Sep 2011 19:38:14 -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 p8FMc8WM013743; Thu, 15 Sep 2011 18:38:08 -0400 (EDT) To: Merlin Moncure cc: Heikki Linnakangas , Peter Geoghegan , Stefan Keller , pgsql-performance@postgresql.org Subject: Re: Hash index use presently(?) discouraged since 2005: revive or bury it? In-reply-to: References: <16096.1315959870@sss.pgh.pa.us> <4E706DFE.40801@enterprisedb.com> Comments: In-reply-to Merlin Moncure message dated "Thu, 15 Sep 2011 15:00:28 -0500" Date: Thu, 15 Sep 2011 18:38:08 -0400 Message-ID: <13742.1316126288@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-2.404 tagged_above=-10 required=5 tests=BAYES_00=-1.9, RP_MATCHES_RCVD=-0.504 X-Spam-Level: X-Archive-Number: 201109/228 X-Sequence-Number: 45004 Merlin Moncure writes: > HM, what if you junked the current hash indexam, and just implemented > a wrapper over btree so that the 'hash index' was just short hand for > hashing the value into a standard index? Surely creating such a wrapper would be *more* work than adding WAL support to the hash AM. I'm not entirely following this eagerness to junk that AM, anyway. We've put a lot of sweat into it over the years, in the hopes that it would eventually be good for something. It's on the edge of being good for something now, and there's doubtless room for more improvements, so why are the knives out? regards, tom lane