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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2018-07-19 13:49:43 +0300 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2018-07-19 13:49:43 +0300 |
| commit | 5220bb7533f9891b1e071da6461d5c387e8f7b09 (patch) | |
| tree | bdf9a0a35879d8d1eacae28f9eac2cfdea79c3cf /doc/src | |
| parent | b33ef397a1698ddd06f325d0f92a6643ec55577f (diff) | |
Expand run-time partition pruning to work with MergeAppend
This expands the support for the run-time partition pruning which was added
for Append in 499be013de to also allow unneeded subnodes of a MergeAppend
to be removed.
Author: David Rowley
Discussion: https://www.postgresql.org/message-id/CAKJS1f_F_V8D7Wu-HVdnH7zCUxhoGK8XhLLtd%3DCu85qDZzXrgg%40mail.gmail.com
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/perform.sgml | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml index b50357c3b4e..262f30fd4c7 100644 --- a/doc/src/sgml/perform.sgml +++ b/doc/src/sgml/perform.sgml @@ -899,12 +899,12 @@ EXPLAIN ANALYZE SELECT * FROM tenk1 WHERE unique1 < 100 AND unique2 > 9000 Generally, the <command>EXPLAIN</command> output will display details for every plan node which was generated by the query planner. However, there are cases where the executor is able to determine that certain nodes are - not required; currently, the only node type to support this is the - <literal>Append</literal> node. This node type has the ability to discard - subnodes which it is able to determine won't contain any records required - by the query. It is possible to determine that nodes have been removed in - this way by the presence of a "Subplans Removed" property in the - <command>EXPLAIN</command> output. + not required; currently, the only node types to support this are the + <literal>Append</literal> and <literal>MergeAppend</literal> nodes. These + node types have the ability to discard subnodes which they are able to + determine won't contain any records required by the query. It is possible + to determine that nodes have been removed in this way by the presence of a + "Subplans Removed" property in the <command>EXPLAIN</command> output. </para> </sect2> |