Fix run-time partition pruning for appends with multiple source rels.

The previous coding here supposed that if run-time partitioning applied to
a particular Append/MergeAppend plan, then all child plans of that node
must be members of a single partitioning hierarchy.  This is totally wrong,
since an Append could be formed from a UNION ALL: we could have multiple
hierarchies sharing the same Append, or child plans that aren't part of any
hierarchy.

To fix, restructure the related plan-time and execution-time data
structures so that we can have a separate list or array for each
partitioning hierarchy.  Also track subplans that are not part of any
hierarchy, and make sure they don't get pruned.

Per reports from Phil Florent and others.  Back-patch to v11, since
the bug originated there.

David Rowley, with a lot of cosmetic adjustments by me; thanks also
to Amit Langote for review.

Discussion: https://postgr.es/m/HE1PR03MB17068BB27404C90B5B788BCABA7B0@HE1PR03MB1706.eurprd03.prod.outlook.com

1 files changed, 38 insertions, 16 deletions

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index b80df601cd..7c2abbd03a 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -241,6 +241,8 @@ typedef struct ModifyTable
 	List	   *exclRelTlist;	/* tlist of the EXCLUDED pseudo relation */
 } ModifyTable;
 
+struct PartitionPruneInfo;		/* forward reference to struct below */
+
 /* ----------------
  *	 Append node -
  *		Generate the concatenation of the results of sub-plans.
@@ -260,8 +262,8 @@ typedef struct Append
 	/* RT indexes of non-leaf tables in a partition tree */
 	List	   *partitioned_rels;
 
-	/* Info for run-time subplan pruning, one entry per partitioned_rels */
-	List	   *part_prune_infos;	/* List of PartitionPruneInfo */
+	/* Info for run-time subplan pruning; NULL if we're not doing that */
+	struct PartitionPruneInfo *part_prune_info;
 } Append;
 
 /* ----------------
@@ -281,9 +283,8 @@ typedef struct MergeAppend
 	Oid		   *sortOperators;	/* OIDs of operators to sort them by */
 	Oid		   *collations;		/* OIDs of collations */
 	bool	   *nullsFirst;		/* NULLS FIRST/LAST directions */
-
-	/* Info for run-time subplan pruning, one entry per partitioned_rels */
-	List	   *part_prune_infos;	/* List of PartitionPruneInfo */
+	/* Info for run-time subplan pruning; NULL if we're not doing that */
+	struct PartitionPruneInfo *part_prune_info;
 } MergeAppend;
 
 /* ----------------
@@ -1063,12 +1064,32 @@ typedef struct PlanRowMark
  * We also store various details to tell the executor when it should be
  * performing partition pruning.
  *
- * Each PartitionPruneInfo describes the partitioning rules for a single
- * partitioned table (a/k/a level of partitioning).  For a multilevel
- * partitioned table, we have a List of PartitionPruneInfos, where the
- * first entry represents the topmost partitioned table and additional
- * entries represent non-leaf child partitions, ordered such that parents
- * appear before their children.
+ * Each PartitionedRelPruneInfo describes the partitioning rules for a single
+ * partitioned table (a/k/a level of partitioning).  Since a partitioning
+ * hierarchy could contain multiple levels, we represent it by a List of
+ * PartitionedRelPruneInfos, where the first entry represents the topmost
+ * partitioned table and additional entries represent non-leaf child
+ * partitions, ordered such that parents appear before their children.
+ * Then, since an Append-type node could have multiple partitioning
+ * hierarchies among its children, we have an unordered List of those Lists.
+ *
+ * prune_infos			List of Lists containing PartitionedRelPruneInfo nodes,
+ *						one sublist per run-time-prunable partition hierarchy
+ *						appearing in the parent plan node's subplans.
+ * other_subplans		Indexes of any subplans that are not accounted for
+ *						by any of the PartitionedRelPruneInfo nodes in
+ *						"prune_infos".  These subplans must not be pruned.
+ */
+typedef struct PartitionPruneInfo
+{
+	NodeTag		type;
+	List	   *prune_infos;
+	Bitmapset  *other_subplans;
+} PartitionPruneInfo;
+
+/*
+ * PartitionedRelPruneInfo - Details required to allow the executor to prune
+ * partitions for a single partitioned table.
  *
  * subplan_map[] and subpart_map[] are indexed by partition index (where
  * zero is the topmost partition, and non-leaf partitions must come before
@@ -1076,11 +1097,12 @@ typedef struct PlanRowMark
  * zero-based index of the partition's subplan in the parent plan's subplan
  * list; it is -1 if the partition is non-leaf or has been pruned.  For a
  * non-leaf partition p, subpart_map[p] contains the zero-based index of
- * that sub-partition's PartitionPruneInfo in the plan's PartitionPruneInfo
- * list; it is -1 if the partition is a leaf or has been pruned.  All these
- * indexes are global across the whole partitioned table and Append plan node.
+ * that sub-partition's PartitionedRelPruneInfo in the hierarchy's
+ * PartitionedRelPruneInfo list; it is -1 if the partition is a leaf or has
+ * been pruned.  Note that subplan indexes are global across the parent plan
+ * node, but partition indexes are valid only within a particular hierarchy.
  */
-typedef struct PartitionPruneInfo
+typedef struct PartitionedRelPruneInfo
 {
 	NodeTag		type;
 	Oid			reloid;			/* OID of partition rel for this level */
@@ -1098,7 +1120,7 @@ typedef struct PartitionPruneInfo
 	bool		do_exec_prune;	/* true if pruning should be performed during
 								 * executor run. */
 	Bitmapset  *execparamids;	/* All PARAM_EXEC Param IDs in pruning_steps */
-} PartitionPruneInfo;
+} PartitionedRelPruneInfo;
 
 /*
  * Abstract Node type for partition pruning steps (there are no concrete