Received: from localhost (unknown [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id 9FF642E00C4 for ; Sun, 2 Dec 2007 20:56:26 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024) with ESMTP id 72753-01 for ; Sun, 2 Dec 2007 20:56:16 -0400 (AST) Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 15CE52E0032 for ; Sun, 2 Dec 2007 20:56:20 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.1/8.14.1) with ESMTP id lB30uJ5x000240; Sun, 2 Dec 2007 19:56:19 -0500 (EST) To: Michael Glaesemann cc: pgsql-performance@postgresql.org Subject: Re: EXPLAIN ANALYZE time calculations In-reply-to: <8C0EE80A-42A3-4CC1-850B-2A6B9220B422@seespotcode.net> References: <8C0EE80A-42A3-4CC1-850B-2A6B9220B422@seespotcode.net> Comments: In-reply-to Michael Glaesemann message dated "Sun, 02 Dec 2007 19:28:15 -0500" Date: Sun, 02 Dec 2007 19:56:19 -0500 Message-ID: <239.1196643379@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200712/21 X-Sequence-Number: 27837 Michael Glaesemann writes: > I'd like to get confirmation that I'm correctly understanding the > times given in EXPLAIN ANALYZE. > ... > Is this correct? Looks about right to me. Note that some of what you are calling "executor overhead" might also be classed as "gettimeofday overhead". The measured difference between two successive gettimeofday readings presumably includes the actual userland runtime plus the equivalent of one gettimeofday call; but we actually did two calls. IOW the actual time to get in and out of a node is going to be a shade more than is reported. regards, tom lane