From f760a8b5cc1fa8c9d341faaf2cbda3b94d5a20d9 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Mon, 17 Dec 2018 11:44:19 -0300 Subject: [PATCH] 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 --- doc/src/sgml/ddl.sgml | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index 5ae3cacbf0..5e5c3d7057 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -3921,8 +3921,12 @@ EXPLAIN SELECT count(*) FROM measurement WHERE logdate >= 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 nloops property in - the EXPLAIN ANALYZE output. + careful inspection of the loops property in + the EXPLAIN ANALYZE 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 (never executed) + if they were pruned every time.