Hi David. On 2018/04/09 12:48, David Rowley wrote: > While looking at the docs in , I saw that we still mention: > > 4. Ensure that the constraint_exclusion configuration parameter is not > disabled in postgresql.conf. If it is, queries will not be optimized > as desired. > > This is no longer true. The attached patch removed it. > >  https://www.postgresql.org/docs/10/static/ddl-partitioning.htm Thanks. I was aware of the changes that would need to be made, but you beat me to writing the patch itself.
About the patch: While the users no longer need to enable constraint_exclusion true for select queries, one would still need it for update/delete queries, because the new pruning logic only gets invoked for the former. Alas... Also, further down on that page, there is a 5.10.4 Partitioning and Constraint Exclusion sub-section. I think it would also need some tweaks due to new developments. I updated your patch to fix that. Please take a look. Thanks, Amit
From a4fe924936fe623ff95e6aa050b8fd7d22dbbb84 Mon Sep 17 00:00:00 2001 From: "dgrow...@gmail.com" <dgrow...@gmail.com> Date: Mon, 9 Apr 2018 15:43:32 +1200 Subject: [PATCH v2] Remove mention of constraint_exclusion in partitioning docs As of 9fdb675fc5d2, this GUC now no longer has an affect on partition pruning. --- doc/src/sgml/ddl.sgml | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index feb2ab7792..eed8753e24 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -3194,13 +3194,14 @@ CREATE INDEX ON measurement (logdate); </para> </listitem> - <listitem> - <para> - Ensure that the <xref linkend="guc-constraint-exclusion"/> - configuration parameter is not disabled in <filename>postgresql.conf</filename>. - If it is, queries will not be optimized as desired. - </para> - </listitem> + <listitem> + <para> + Ensure that the <xref linkend="guc-constraint-exclusion"/> + configuration parameter is not disabled in <filename>postgresql.conf</filename>. + While enabling it is not required for select queries, not doing so will result + in update and delete queries to not be optimized as desired. + </para> + </listitem> </orderedlist> </para> @@ -3767,10 +3768,12 @@ ANALYZE measurement; </indexterm> <para> - <firstterm>Constraint exclusion</firstterm> is a query optimization technique - that improves performance for partitioned tables defined in the - fashion described above (both declaratively partitioned tables and those - implemented using inheritance). As an example: + <firstterm>Constraint exclusion</firstterm> is a query optimization + technique that improves performance for partitioned tables defined in the + fashion described above. While it is used only for update and delete + queries in the case of declaratively partitioned tables, it is used for all + queries in the case of table partitioning implemented using inheritance. + As an example: <programlisting> SET constraint_exclusion = on; -- 2.11.0