public inbox for [email protected]
help / color / mirror / Atom feedFrom: Bruce Momjian <[email protected]>
To: David Rowley <[email protected]>
Cc: Amit Langote <[email protected]>
Cc: Jonathan S. Katz <[email protected]>
Cc: [email protected]
Subject: Re: PostgreSQL 12: Feature Highlights
Date: Thu, 13 Jun 2019 23:24:39 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAKJS1f9FL6oKd52PLddKsbjkX26JHp5nMRxVA-W9Uf_1a9TwgA@mail.gmail.com>
References: <[email protected]>
<[email protected]>
<[email protected]>
<CAKJS1f_c8tngWJZjNcQY0KXHWVs4JZxyzoX_cGBEHbaWKUAC=w@mail.gmail.com>
<[email protected]>
<CAKJS1f8R8riwBXw==7ijV=UZNuhP+3qXgDBKSiM+=_cTf4mXXw@mail.gmail.com>
<[email protected]>
<CAKJS1f9TVMvGQdwxMemci34viPZuiLTFOJa4rc1Bfhm57WycFA@mail.gmail.com>
<[email protected]>
<CAKJS1f9FL6oKd52PLddKsbjkX26JHp5nMRxVA-W9Uf_1a9TwgA@mail.gmail.com>
On Wed, May 22, 2019 at 12:33:10PM +1200, David Rowley wrote:
> On Wed, 22 May 2019 at 02:55, Bruce Momjian <[email protected]> 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 <[email protected]> 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 +
Attachments:
[text/x-diff] append.diff (782B, ../[email protected]/2-append.diff)
download | inline 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 <[email protected]>
*** 842,847 ****
--- 842,859 ----
<listitem>
<!--
Author: Tom Lane <[email protected]>
+ 2019-03-25 [8edd0e794] Suppress Append and MergeAppend plan nodes that have a s
+ -->
+
+ <para>
+ Improve optimization of partition and <literal>UNION ALL</literal>
+ queries that have only a single child (David Rowley)
+ </para>
+ </listitem>
+
+ <listitem>
+ <!--
+ Author: Tom Lane <[email protected]>
2018-12-13 [04fe805a1] Drop no-op CoerceToDomain nodes from expressions at plan
-->
view thread (63+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected], [email protected], [email protected], [email protected], [email protected]
Subject: Re: PostgreSQL 12: Feature Highlights
In-Reply-To: <[email protected]>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox