Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id CDDE911DF225; Thu, 31 May 2012 12:25:51 -0300 (ADT) Received: from sss.pgh.pa.us ([66.207.139.130]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1Sa7G3-0000UZ-0b; Thu, 31 May 2012 15:25:51 +0000 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 q4VFPbqP013350; Thu, 31 May 2012 11:25:37 -0400 (EDT) To: Claudio Freire cc: Robert Haas , Robert Klemme , Tatsuo Ishii , pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org Subject: Re: [HACKERS] pg_dump and thousands of schemas In-reply-to: References: <20120529.185149.1127748531209576379.t-ishii@sraoss.co.jp> <20120531.174526.2183902405630094684.t-ishii@sraoss.co.jp> <20120531.230757.2014494683420217075.t-ishii@sraoss.co.jp> <9787.1338474676@sss.pgh.pa.us> <10443.1338475851@sss.pgh.pa.us> Comments: In-reply-to Claudio Freire message dated "Thu, 31 May 2012 12:01:42 -0300" Date: Thu, 31 May 2012 11:25:37 -0400 Message-ID: <13349.1338477937@sss.pgh.pa.us> From: Tom Lane X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201205/194 X-Sequence-Number: 47018 Claudio Freire writes: > On Thu, May 31, 2012 at 11:50 AM, Tom Lane wrote: >> The performance patches we applied to pg_dump over the past couple weeks >> were meant to relieve pain in situations where the big server-side >> lossage wasn't the dominant factor in runtime (ie, partial dumps). >> But this one is targeting exactly that area, which is why it looks like >> a band-aid and not a fix to me. > No, Tatsuo's patch attacks a phase dominated by latency in some > setups. No, it does not. The reason it's a win is that it avoids the O(N^2) behavior in the server. Whether the bandwidth savings is worth worrying about cannot be proven one way or the other as long as that elephant is in the room. regards, tom lane