diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml index 715aff6..0f61b09 100644 --- a/doc/src/sgml/perform.sgml +++ b/doc/src/sgml/perform.sgml @@ -896,15 +896,16 @@ EXPLAIN ANALYZE SELECT * FROM tenk1 WHERE unique1 < 100 AND unique2 > 9000 - Generally, the EXPLAIN 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 types to support this are the - Append and MergeAppend 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 EXPLAIN output. + Normally, EXPLAIN will display every plan node + created by the planner. However, there are cases where the executor + can determine that certain nodes need not be executed because they + cannot produce any rows, based on parameter values that were not + available at planning time. (Currently this can only happen for child + nodes of an Append or MergeAppend node that is scanning a partitioned + table.) When this happens, those plan nodes are omitted from + the EXPLAIN output and a Subplans + Removed: N annotation appears + instead.