Received: from localhost (unknown [200.46.204.184]) by developer.postgresql.org (Postfix) with ESMTP id F064E2E005F for ; Fri, 18 Apr 2008 16:09:21 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 70033-02 for ; Fri, 18 Apr 2008 16:09:09 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by developer.postgresql.org (Postfix) with ESMTP id 468272E003D for ; Fri, 18 Apr 2008 16:09:12 -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 m3IJ984O006257; Fri, 18 Apr 2008 15:09:09 -0400 (EDT) To: "Jeffrey Baker" cc: pgsql-performance@postgresql.org Subject: Re: 3-days-long vacuum of 20GB table In-reply-to: References: <3630.1208538238@sss.pgh.pa.us> Comments: In-reply-to "Jeffrey Baker" message dated "Fri, 18 Apr 2008 10:54:24 -0700" Date: Fri, 18 Apr 2008 15:09:08 -0400 Message-ID: <6256.1208545748@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200804/278 X-Sequence-Number: 29771 "Jeffrey Baker" writes: > I increased it to 1GB, restarted the vacuum, and system performance > seems the same. The root of the problem, that an entire CPU is in the > iowait state and the storage device is doing random i/o, is unchanged: Yeah, but you just reduced the number of index scans that will be needed by a factor of 1GB/16MB. Hang in there ... regards, tom lane