Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.84_2) (envelope-from ) id 1coEni-0006yH-Qq for pgsql-hackers@arkaria.postgresql.org; Wed, 15 Mar 2017 19:41:38 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.84_2) (envelope-from ) id 1coEni-0007Gh-A4 for pgsql-hackers@arkaria.postgresql.org; Wed, 15 Mar 2017 19:41:38 +0000 Received: from makus.postgresql.org ([2001:4800:1501:1::229]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1coEng-0007EG-B4 for pgsql-hackers@postgresql.org; Wed, 15 Mar 2017 19:41:36 +0000 Received: from sss.pgh.pa.us ([66.207.139.130]) by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1coEnd-0006hv-S6 for pgsql-hackers@postgresql.org; Wed, 15 Mar 2017 19:41:35 +0000 Received: from sss1.sss.pgh.pa.us (localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.4/8.14.4) with ESMTP id v2FJfMuD003402; Wed, 15 Mar 2017 15:41:22 -0400 From: Tom Lane To: Andres Freund cc: pgsql-hackers@postgresql.org, Heikki Linnakangas , Tomas Vondra Subject: Re: WIP: Faster Expression Processing v4 In-reply-to: <855716B2-7522-4C79-A50E-2EB8E609764F@anarazel.de> References: <20161206034955.bh33paeralxbtluv@alap3.anarazel.de> <20170209003312.rr7atqepgbrf4xqe@alap3.anarazel.de> <20170307030137.lpo4japv5oqgbqpz@alap3.anarazel.de> <2090fd00-4dec-7b42-f700-64308958504c@2ndquadrant.com> <20170313080351.4g5oubxcj4xj5y7t@alap3.anarazel.de> <20170314065259.ffef4tfhgbsaieoe@alap3.anarazel.de> <69b7bb0e-8dab-3d39-1a89-3c6ab6409f64@iki.fi> <20170314224706.nxvtapenky6eom3z@alap3.anarazel.de> <3086.1489606408@sss.pgh.pa.us> <855716B2-7522-4C79-A50E-2EB8E609764F@anarazel.de> Comments: In-reply-to Andres Freund message dated "Wed, 15 Mar 2017 12:38:15 -0700" MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3400.1489606882.1@sss.pgh.pa.us> Content-Transfer-Encoding: quoted-printable Date: Wed, 15 Mar 2017 15:41:22 -0400 Message-ID: <3401.1489606882@sss.pgh.pa.us> X-Pg-Spam-Score: -1.9 (-) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-hackers Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org Andres Freund writes: > On March 15, 2017 12:33:28 PM PDT, Tom Lane wrote: >> So for my money, you should drop 0002 altogether and just have 0004 >> remove get_last_attnums() from execUtils.c and stick it into >> execExpr.c. I suppose you still need the LastAttnumInfo API change >> so as to decouple it from ProjectionInfo, but that's minor. > I think it's quite useful in other places too, we do repeated slot-getatt= rs in a bunch of places in the executor, and it's noticeable performance wi= se.=20 Color me dubious. Which specific other places have you got in mind, and do they have expression trees at hand that would tell them which columns they really need to pull out? regards, tom lane --=20 Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers