Received: from localhost (maia-1.hub.org [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id DEE289FA141 for ; Thu, 22 Mar 2007 12:37:21 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.191]) (amavisd-new, port 10024) with ESMTP id 33161-01-10 for ; Thu, 22 Mar 2007 12:37:11 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id E4FC99FA2C4 for ; Thu, 22 Mar 2007 12:35:41 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.6/8.13.6) with ESMTP id l2MFZadR003702; Thu, 22 Mar 2007 11:35:37 -0400 (EDT) To: Bill Moran cc: David Brain , pgsql-performance@postgresql.org Subject: Re: Potential memory usage issue In-reply-to: <20070322091700.9d1553e6.wmoran@collaborativefusion.com> References: <460271B9.8050600@bandwidth.com> <20070322085037.54780906.wmoran@collaborativefusion.com> <46027F65.9080909@bandwidth.com> <20070322091700.9d1553e6.wmoran@collaborativefusion.com> Comments: In-reply-to Bill Moran message dated "Thu, 22 Mar 2007 09:17:00 -0400" Date: Thu, 22 Mar 2007 11:35:36 -0400 Message-ID: <3701.1174577736@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200703/332 X-Sequence-Number: 23737 Bill Moran writes: > In response to David Brain : >> I am curious as to why 'top' gives such different output on the two >> systems - the datasets are large and so I know I benefit from having >> high shared_buffers and effective_cache_size settings. > Have you done any actual queries on the new system? PG won't use the > shm until it needs it -- and that doesn't occur until it gets a request > for data via a query. More accurately, top won't consider shared mem to be part of the process address space until it's actually touched by that process. regards, tom lane