diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 17 | ||||
| -rw-r--r-- | doc/src/sgml/ddl.sgml | 17 |
2 files changed, 13 insertions, 21 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 8ddab75b5ab..84341a30e56 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -5084,10 +5084,11 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class=" The allowed values of <varname>constraint_exclusion</varname> are <literal>on</literal> (examine constraints for all tables), <literal>off</literal> (never examine constraints), and - <literal>partition</literal> (examine constraints only for inheritance child - tables and <literal>UNION ALL</literal> subqueries). + <literal>partition</literal> (examine constraints only for inheritance + child tables and <literal>UNION ALL</literal> subqueries). <literal>partition</literal> is the default setting. - It is often used with inheritance tables to improve performance. + It is often used with traditional inheritance trees to improve + performance. </para> <para> @@ -5111,15 +5112,19 @@ SELECT * FROM parent WHERE key = 2400; <para> Currently, constraint exclusion is enabled by default only for cases that are often used to implement table partitioning via - inheritance tables. Turning it on for all tables imposes extra + inheritance trees. Turning it on for all tables imposes extra planning overhead that is quite noticeable on simple queries, and most often will yield no benefit for simple queries. If you have no - inheritance partitioned tables you might prefer to turn it off entirely. + tables that are partitioned using traditional inheritance, you might + prefer to turn it off entirely. (Note that the equivalent feature for + partitioned tables is controlled by a separate parameter, + <xref linkend="guc-enable-partition-pruning"/>.) </para> <para> Refer to <xref linkend="ddl-partitioning-constraint-exclusion"/> for - more information on using constraint exclusion and partitioning. + more information on using constraint exclusion to implement + partitioning. </para> </listitem> </varlistentry> diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index cba2ea9b2b7..a0a7435a03d 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -4535,24 +4535,11 @@ EXPLAIN SELECT count(*) FROM measurement WHERE logdate >= DATE '2008-01-01'; <note> <para> - Currently, pruning of partitions during the planning of an - <command>UPDATE</command> or <command>DELETE</command> command is - implemented using the constraint exclusion method (however, it is - controlled by the <literal>enable_partition_pruning</literal> rather than - <literal>constraint_exclusion</literal>) — see the following section - for details and caveats that apply. - </para> - - <para> Execution-time partition pruning currently only occurs for the <literal>Append</literal> and <literal>MergeAppend</literal> node types. It is not yet implemented for the <literal>ModifyTable</literal> node - type. - </para> - - <para> - Both of these behaviors are likely to be changed in a future release - of <productname>PostgreSQL</productname>. + type, but that is likely to be changed in a future release of + <productname>PostgreSQL</productname>. </para> </note> </sect2> |