Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1Txo7S-0000Ip-Oq for pgsql-admin@arkaria.postgresql.org; Wed, 23 Jan 2013 00:23:10 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.72) (envelope-from ) id 1Txo7R-0003hG-IE for pgsql-admin@arkaria.postgresql.org; Wed, 23 Jan 2013 00:23:09 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1Txo7Q-0003hA-KZ for pgsql-admin@postgresql.org; Wed, 23 Jan 2013 00:23:08 +0000 Received: from mout.gmx.net ([74.208.4.200]) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1Txo7L-0001Vu-TG for pgsql-admin@postgresql.org; Wed, 23 Jan 2013 00:23:07 +0000 Received: from mailout-us.gmx.com ([172.19.198.46]) by mrigmx.server.lan (mrigmxus001) with ESMTP (Nemesis) id 0LjZi0-1TMXUc03Uu-00bbbc for ; Wed, 23 Jan 2013 01:23:02 +0100 Received: (qmail 1059 invoked by uid 0); 23 Jan 2013 00:23:01 -0000 Received: from 76.255.19.161 by rms-us013 with HTTP Content-Type: text/plain; charset="utf-8" Date: Tue, 22 Jan 2013 19:23:01 -0500 From: "Kevin Grittner" Message-ID: <20130123002301.120590@gmx.com> MIME-Version: 1.0 Subject: Re: Schema design question as it pertains to performance To: "Benjamin Krajmalnik" ,pgsql-admin@postgresql.org X-Authenticated: #138763884 X-Flags: 0001 X-Mailer: GMX.com Web Mailer x-registered: 0 Content-Transfer-Encoding: 8bit X-GMX-UID: MkiNcH9O3zOlOQ09LnwhCBp+IGRvbwA8 X-Pg-Spam-Score: -2.6 (--) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-admin Precedence: bulk Sender: pgsql-admin-owner@postgresql.org Benjamin Krajmalnik wrote: > Kevin Grittner wrote: >> Benjamin Krajmalnik wrote: >>> I also assume that if no data has changed in an index, nothing >>> is done when the record is updated as pertains to the >>> particular index - am I correct in this assumption? >> >> No. [...] If any indexed column is updated, [...] it needs new >> entries in all the indexes. > That was my intent - if no column of an index changes in an > update then no changes are done on the index. I don't think you understood -- if any column referenced by any index is updated, then all indexes must get a new entry for that row whether or not they include that column. The new version of the row will be at a new location, so new entries are needed in all indexes to point to the new location. I did *not* say that only indexes referencing the updated column need a new entry. -Kevin -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin