Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hbcqd-0004yZ-H5 for pgsql-advocacy@arkaria.postgresql.org; Fri, 14 Jun 2019 03:25:51 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.89) (envelope-from ) id 1hbcpe-0008SK-5y for pgsql-advocacy@arkaria.postgresql.org; Fri, 14 Jun 2019 03:24:50 +0000 Received: from makus.postgresql.org ([2001:4800:3e1:1::229]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hbcpd-0008S6-KU for pgsql-advocacy@lists.postgresql.org; Fri, 14 Jun 2019 03:24:49 +0000 Received: from momjian.us ([72.94.173.45]) by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hbcpW-0003yk-MN; Fri, 14 Jun 2019 03:24:48 +0000 Received: from bruce by momjian.us with local (Exim 4.89) (envelope-from ) id 1hbcpT-0001sH-Ox; Thu, 13 Jun 2019 23:24:39 -0400 Date: Thu, 13 Jun 2019 23:24:39 -0400 From: Bruce Momjian To: David Rowley Cc: Amit Langote , "Jonathan S. Katz" , pgsql-advocacy@lists.postgresql.org Subject: Re: PostgreSQL 12: Feature Highlights Message-ID: <20190614032439.vrv7tvvyez5j2xog@momjian.us> References: <20190516182628.kbkiajfnlooocgyg@momjian.us> <0cf10a27-c6a0-de4a-cd20-ab7493ea7422@lab.ntt.co.jp> <20190517153653.pmolnulev6imwsn3@momjian.us> <20190518023017.nkucoc5xgoebtvfw@momjian.us> <20190518132031.zjyxgvys7unan53f@momjian.us> <20190521145509.s6bme6pgww3glmku@momjian.us> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="y22ljr5u4c2irt4p" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk --y22ljr5u4c2irt4p Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, May 22, 2019 at 12:33:10PM +1200, David Rowley wrote: > On Wed, 22 May 2019 at 02:55, Bruce Momjian wrote: > > This brings up a few points. First, it seems the change affects > > partitioned tables and UNION ALL, which means it probably needs to be > > listed in two sections. Second, is it only parallelism paths that are > > added? I am not sure if people care about a node being removed, > > especially when the might not even know we do that step, but they do > > care if there are new optimization possibilities. > > Like Amit, I think the optimizer section is fine. Another thing that > is affected is that you may no longer get a Materialize node in the > plan. Previously you might have gotten something like Merge Join -> > Materialize -> Append -> Seq Scan, now you might just get Merge Join > -> Seq Scan. This is because Append / MergeAppend don't support mark > and restore. Removing them would allow the materialize node to be > skipped in cases where the single subpath of the Append does support > mark and restore. How is this patch for the item? I put it in the Optimizer section. -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription + --y22ljr5u4c2irt4p Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="append.diff" diff --git a/doc/src/sgml/release-12.sgml b/doc/src/sgml/release-12.sgml new file mode 100644 index 76abc95..aa3845f *** a/doc/src/sgml/release-12.sgml --- b/doc/src/sgml/release-12.sgml *************** Author: Tom Lane *** 842,847 **** --- 842,859 ---- + + + Improve optimization of partition and UNION ALL + queries that have only a single child (David Rowley) + + + + + --y22ljr5u4c2irt4p--