Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 937FF1337B7E for ; Fri, 14 Jan 2011 13:56:18 -0400 (AST) 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 29262-02 for ; Fri, 14 Jan 2011 17:56:11 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id 4CA791337B92 for ; Fri, 14 Jan 2011 13:56:05 -0400 (AST) 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 p0EHu2uA008295; Fri, 14 Jan 2011 12:56:02 -0500 (EST) To: =?iso-2022-jp?B?GyRCQ2ZAbiEhQD81LhsoQg==?= cc: pgsql-sql@postgresql.org Subject: Re: why does seq scan instead of index scan In-reply-to: <49A94E2FF0F642B4ACBE09DB20CA5630@IVPNAKAGAWAPC> References: <49A94E2FF0F642B4ACBE09DB20CA5630@IVPNAKAGAWAPC> Comments: In-reply-to =?iso-2022-jp?B?GyRCQ2ZAbiEhQD81LhsoQg==?= message dated "Fri, 14 Jan 2011 17:58:43 +0900" Date: Fri, 14 Jan 2011 12:56:02 -0500 Message-ID: <8294.1295027762@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-5 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201101/40 X-Sequence-Number: 34987 =?iso-2022-jp?B?GyRCQ2ZAbiEhQD81LhsoQg==?= writes: > I'm trying to use like 'xx%' search on Text[] column. > I thought it uses index scan. But actually it uses seq scan. > Why? Those ANY expressions are not indexable. regards, tom lane