From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Mon, 17 Dec 2018 14:44:36 +0000 (-0300)
Subject: Clarify runtime pruning in EXPLAIN
X-Git-Tag: REL_12_BETA1~1065
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1e6240a3fe919e19676875927681a861e13f93c2;p=thirdparty%2Fpostgresql.git

Clarify runtime pruning in EXPLAIN

Author: Amit Langote
Reviewed-by: David Rowley
Discussion: https://postgr.es/m/002dec69-9afb-b621-5630-235eceafe0bd@lab.ntt.co.jp
---

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 1925ff45509..85e43589882 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -4421,8 +4421,12 @@ EXPLAIN SELECT count(*) FROM measurement WHERE logdate &gt;= DATE '2008-01-01';
        query, partition pruning is performed whenever one of the
        execution parameters being used by partition pruning changes.
        Determining if partitions were pruned during this phase requires
-       careful inspection of the <literal>nloops</literal> property in
-       the <command>EXPLAIN ANALYZE</command> output.
+       careful inspection of the <literal>loops</literal> property in
+       the <command>EXPLAIN ANALYZE</command> output.  Subplans
+       corresponding to different partitions may have different values
+       for it depending on how many times each of them was pruned during
+       execution.  Some may be shown as <literal>(never executed)</literal>
+       if they were pruned every time.
       </para>
      </listitem>
     </itemizedlist>