Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id 49BFF29F0D5 for ; Mon, 12 Mar 2012 13:34:51 -0300 (ADT) Received: from sam.nabble.com ([216.139.236.26]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1S78Cv-0004j2-Eq for pgsql-performance@postgresql.org; Mon, 12 Mar 2012 16:34:50 +0000 Received: from [192.168.236.26] (helo=sam.nabble.com) by sam.nabble.com with esmtp (Exim 4.72) (envelope-from ) id 1S78Cj-0006Vs-4y for pgsql-performance@postgresql.org; Mon, 12 Mar 2012 09:34:37 -0700 Date: Mon, 12 Mar 2012 09:34:37 -0700 (PDT) From: ddgs To: pgsql-performance@postgresql.org Message-ID: <1331570077139-5558345.post@n5.nabble.com> In-Reply-To: <4F5DD88F020000250004610B@gw.wicourts.gov> References: <1331307029713-5550894.post@n5.nabble.com> <4F5DC49D02000025000460F6@gw.wicourts.gov> <1331567213547-5558198.post@n5.nabble.com> <4F5DD88F020000250004610B@gw.wicourts.gov> Subject: Re: count on transaction ID MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: 0.0 (/) X-Archive-Number: 201203/97 X-Sequence-Number: 46547 Is it a good starting point to the basic reason of doing vacuum? from the manual, "PostgreSQL's VACUUM command must be run on a regular basis for several reasons: To recover disk space occupied by updated or deleted rows. To update data statistics used by the PostgreSQL query planner. To protect against loss of very old data due to transaction ID wraparound. " It seems that only transaction ID wraparound can cause system failure in loading-in new data. For the dead rows problem, it just a matter of space; the data statistics is just relate to the query performance. -- View this message in context: http://postgresql.1045698.n5.nabble.com/count-on-transaction-ID-tp5550894p5558345.html Sent from the PostgreSQL - performance mailing list archive at Nabble.com.