Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id DC41165040A for ; Thu, 21 Aug 2008 22:08:16 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 45377-09 for ; Thu, 21 Aug 2008 22:07:52 -0300 (ADT) 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 postgresql.org (Postfix) with ESMTP id A716C6500AC for ; Thu, 21 Aug 2008 21:49:19 -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 m7M0nHbX027301; Thu, 21 Aug 2008 20:49:17 -0400 (EDT) To: pgsql-performance@ian.org cc: pgsql-performance@postgresql.org Subject: Re: Why do my hash joins turn to nested loops? In-reply-to: References: <20080821223626.39BC212A6CFB@mx2.hub.org> Comments: In-reply-to pgsql-performance@ian.org message dated "Thu, 21 Aug 2008 18:50:35 -0400" Date: Thu, 21 Aug 2008 20:49:17 -0400 Message-ID: <27300.1219366157@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200808/271 X-Sequence-Number: 31152 pgsql-performance@ian.org writes: > One query works fast, returning results in under a second. If I insert > one more join into the table however, it switches to nested-loops and > takes minutes. I think you need to raise from_collapse_limit and/or join_collapse_limit. regards, tom lane