Move PartitionPruneInfo out of plan nodes into PlannedStmt

This moves PartitionPruneInfo from plan nodes to PlannedStmt,
simplifying traversal by centralizing all PartitionPruneInfo
structures in a single list in it, which holds all instances for the
main query and its subqueries. Instead of plan nodes (Append or
MergeAppend) storing PartitionPruneInfo pointers, they now reference
an index in this list.

A bitmapset field is added to PartitionPruneInfo to store the RT
indexes corresponding to the apprelids field in Append or MergeAppend.
This allows execution pruning logic to verify that it operates on the
correct plan node, mainly to facilitate debugging.

Duplicated code in set_append_references() and
set_mergeappend_references() is refactored into a new function,
register_pruneinfo(). This updates RT indexes by applying rtoffet
and adds PartitionPruneInfo to the global list in PlannerGlobal.

By allowing pruning to be performed without traversing the plan tree,
this change lays the groundwork for runtime initial pruning to occur
independently of plan tree initialization.

Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org> (earlier version)
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Discussion: https://postgr.es/m/CA+HiwqFGkMSge6TgC9KQzde0ohpAycLQuV7ooitEEpbKB0O_mg@mail.gmail.com

src/backend/executor/execMain.c

@@ -853,6 +853,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	ExecInitRangeTable(estate, rangeTable, plannedstmt->permInfos);
 
 	estate->es_plannedstmt = plannedstmt;
+	estate->es_part_prune_infos = plannedstmt->partPruneInfos;
 
 	/*
 	 * Next, build the ExecRowMark array from the PlanRowMark(s), if any.

src/backend/executor/execParallel.c

@@ -181,6 +181,7 @@ ExecSerializePlan(Plan *plan, EState *estate)
 	pstmt->dependsOnRole = false;
 	pstmt->parallelModeNeeded = false;
 	pstmt->planTree = plan;
+	pstmt->partPruneInfos = estate->es_part_prune_infos;
 	pstmt->rtable = estate->es_range_table;
 	pstmt->permInfos = estate->es_rteperminfos;
 	pstmt->resultRelations = NIL;

src/backend/executor/execPartition.c

@@ -1786,6 +1786,9 @@ adjust_partition_colnos_using_map(List *colnos, AttrMap *attrMap)
  *		Initialize data structure needed for run-time partition pruning and
  *		do initial pruning if needed
  *
+ * 'relids' identifies the relation to which both the parent plan and the
+ * PartitionPruneInfo given by 'part_prune_index' belong.
+ *
  * On return, *initially_valid_subplans is assigned the set of indexes of
  * child subplans that must be initialized along with the parent plan node.
  * Initial pruning is performed here if needed and in that case only the
@@ -1798,11 +1801,23 @@ adjust_partition_colnos_using_map(List *colnos, AttrMap *attrMap)
 PartitionPruneState *
 ExecInitPartitionPruning(PlanState *planstate,
 						 int n_total_subplans,
-						 PartitionPruneInfo *pruneinfo,
+						 int part_prune_index,
+						 Bitmapset *relids,
 						 Bitmapset **initially_valid_subplans)
 {
 	PartitionPruneState *prunestate;
 	EState	   *estate = planstate->state;
+	PartitionPruneInfo *pruneinfo;
+
+	/* Obtain the pruneinfo we need. */
+	pruneinfo = list_nth_node(PartitionPruneInfo, estate->es_part_prune_infos,
+							  part_prune_index);
+
+	/* Its relids better match the plan node's or the planner messed up. */
+	if (!bms_equal(relids, pruneinfo->relids))
+		elog(ERROR, "wrong pruneinfo with relids=%s found at part_prune_index=%d contained in plan node with relids=%s",
+			 bmsToString(pruneinfo->relids), part_prune_index,
+			 bmsToString(relids));
 
 	/* We may need an expression context to evaluate partition exprs */
 	ExecAssignExprContext(estate, planstate);

src/backend/executor/execUtils.c

@@ -118,6 +118,7 @@ CreateExecutorState(void)
 	estate->es_rowmarks = NULL;
 	estate->es_rteperminfos = NIL;
 	estate->es_plannedstmt = NULL;
+	estate->es_part_prune_infos = NIL;
 
 	estate->es_junkFilter = NULL;
 

src/backend/executor/nodeAppend.c

@@ -135,7 +135,7 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 	appendstate->as_begun = false;
 
 	/* If run-time partition pruning is enabled, then set that up now */
-	if (node->part_prune_info != NULL)
+	if (node->part_prune_index >= 0)
 	{
 		PartitionPruneState *prunestate;
 
@@ -146,7 +146,8 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		 */
 		prunestate = ExecInitPartitionPruning(&appendstate->ps,
 											  list_length(node->appendplans),
-											  node->part_prune_info,
+											  node->part_prune_index,
+											  node->apprelids,
 											  &validsubplans);
 		appendstate->as_prune_state = prunestate;
 		nplans = bms_num_members(validsubplans);

src/backend/executor/nodeMergeAppend.c

@@ -83,7 +83,7 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 	mergestate->ps.ExecProcNode = ExecMergeAppend;
 
 	/* If run-time partition pruning is enabled, then set that up now */
-	if (node->part_prune_info != NULL)
+	if (node->part_prune_index >= 0)
 	{
 		PartitionPruneState *prunestate;
 
@@ -94,7 +94,8 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		 */
 		prunestate = ExecInitPartitionPruning(&mergestate->ps,
 											  list_length(node->mergeplans),
-											  node->part_prune_info,
+											  node->part_prune_index,
+											  node->apprelids,
 											  &validsubplans);
 		mergestate->ms_prune_state = prunestate;
 		nplans = bms_num_members(validsubplans);

src/backend/optimizer/plan/createplan.c

@@ -1227,7 +1227,6 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	ListCell   *subpaths;
 	int			nasyncplans = 0;
 	RelOptInfo *rel = best_path->path.parent;
-	PartitionPruneInfo *partpruneinfo = NULL;
 	int			nodenumsortkeys = 0;
 	AttrNumber *nodeSortColIdx = NULL;
 	Oid		   *nodeSortOperators = NULL;
@@ -1378,6 +1377,9 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 		subplans = lappend(subplans, subplan);
 	}
 
+	/* Set below if we find quals that we can use to run-time prune */
+	plan->part_prune_index = -1;
+
 	/*
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
@@ -1401,8 +1403,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 		}
 
 		if (prunequal != NIL)
-			partpruneinfo =
-				make_partition_pruneinfo(root, rel,
+			plan->part_prune_index = make_partition_pruneinfo(root, rel,
 															  best_path->subpaths,
 															  prunequal);
 	}
@@ -1410,7 +1411,6 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	plan->appendplans = subplans;
 	plan->nasyncplans = nasyncplans;
 	plan->first_partial_plan = best_path->first_partial_path;
-	plan->part_prune_info = partpruneinfo;
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -1449,7 +1449,6 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	List	   *subplans = NIL;
 	ListCell   *subpaths;
 	RelOptInfo *rel = best_path->path.parent;
-	PartitionPruneInfo *partpruneinfo = NULL;
 
 	/*
 	 * We don't have the actual creation of the MergeAppend node split out
@@ -1542,6 +1541,9 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		subplans = lappend(subplans, subplan);
 	}
 
+	/* Set below if we find quals that we can use to run-time prune */
+	node->part_prune_index = -1;
+
 	/*
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
@@ -1557,13 +1559,12 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		Assert(best_path->path.param_info == NULL);
 
 		if (prunequal != NIL)
-			partpruneinfo = make_partition_pruneinfo(root, rel,
+			node->part_prune_index = make_partition_pruneinfo(root, rel,
 															  best_path->subpaths,
 															  prunequal);
 	}
 
 	node->mergeplans = subplans;
-	node->part_prune_info = partpruneinfo;
 
 	/*
 	 * If prepare_sort_from_pathkeys added sort columns, but we were told to

src/backend/optimizer/plan/planner.c

@@ -555,6 +555,7 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 	result->dependsOnRole = glob->dependsOnRole;
 	result->parallelModeNeeded = glob->parallelModeNeeded;
 	result->planTree = top_plan;
+	result->partPruneInfos = glob->partPruneInfos;
 	result->rtable = glob->finalrtable;
 	result->permInfos = glob->finalrteperminfos;
 	result->resultRelations = glob->resultRelations;

src/backend/optimizer/plan/setrefs.c

@@ -1731,6 +1731,53 @@ set_customscan_references(PlannerInfo *root,
 	cscan->custom_relids = offset_relid_set(cscan->custom_relids, rtoffset);
 }
 
+/*
+ * register_partpruneinfo
+ *		Subroutine for set_append_references and set_mergeappend_references
+ *
+ * Add the PartitionPruneInfo from root->partPruneInfos at the given index
+ * into PlannerGlobal->partPruneInfos and return its index there.
+ *
+ * Also update the RT indexes present in PartitionedRelPruneInfos to add the
+ * offset.
+ */
+static int
+register_partpruneinfo(PlannerInfo *root, int part_prune_index, int rtoffset)
+{
+	PlannerGlobal *glob = root->glob;
+	PartitionPruneInfo *pinfo;
+	ListCell   *l;
+
+	Assert(part_prune_index >= 0 &&
+		   part_prune_index < list_length(root->partPruneInfos));
+	pinfo = list_nth_node(PartitionPruneInfo, root->partPruneInfos,
+						  part_prune_index);
+
+	pinfo->relids = offset_relid_set(pinfo->relids, rtoffset);
+	foreach(l, pinfo->prune_infos)
+	{
+		List	   *prune_infos = lfirst(l);
+		ListCell   *l2;
+
+		foreach(l2, prune_infos)
+		{
+			PartitionedRelPruneInfo *prelinfo = lfirst(l2);
+
+			prelinfo->rtindex += rtoffset;
+			prelinfo->initial_pruning_steps =
+				fix_scan_list(root, prelinfo->initial_pruning_steps,
+							  rtoffset, 1);
+			prelinfo->exec_pruning_steps =
+				fix_scan_list(root, prelinfo->exec_pruning_steps,
+							  rtoffset, 1);
+		}
+	}
+
+	glob->partPruneInfos = lappend(glob->partPruneInfos, pinfo);
+
+	return list_length(glob->partPruneInfos) - 1;
+}
+
 /*
  * set_append_references
  *		Do set_plan_references processing on an Append
@@ -1783,27 +1830,13 @@ set_append_references(PlannerInfo *root,
 
 	aplan->apprelids = offset_relid_set(aplan->apprelids, rtoffset);
 
-	if (aplan->part_prune_info)
-	{
-		foreach(l, aplan->part_prune_info->prune_infos)
-		{
-			List	   *prune_infos = lfirst(l);
-			ListCell   *l2;
-
-			foreach(l2, prune_infos)
-			{
-				PartitionedRelPruneInfo *pinfo = lfirst(l2);
-
-				pinfo->rtindex += rtoffset;
-				pinfo->initial_pruning_steps =
-					fix_scan_list(root, pinfo->initial_pruning_steps,
-								  rtoffset, 1);
-				pinfo->exec_pruning_steps =
-					fix_scan_list(root, pinfo->exec_pruning_steps,
-								  rtoffset, 1);
-			}
-		}
-	}
+	/*
+	 * Add PartitionPruneInfo, if any, to PlannerGlobal and update the index.
+	 * Also update the RT indexes present in it to add the offset.
+	 */
+	if (aplan->part_prune_index >= 0)
+		aplan->part_prune_index =
+			register_partpruneinfo(root, aplan->part_prune_index, rtoffset);
 
 	/* We don't need to recurse to lefttree or righttree ... */
 	Assert(aplan->plan.lefttree == NULL);
@@ -1865,27 +1898,13 @@ set_mergeappend_references(PlannerInfo *root,
 
 	mplan->apprelids = offset_relid_set(mplan->apprelids, rtoffset);
 
-	if (mplan->part_prune_info)
-	{
-		foreach(l, mplan->part_prune_info->prune_infos)
-		{
-			List	   *prune_infos = lfirst(l);
-			ListCell   *l2;
-
-			foreach(l2, prune_infos)
-			{
-				PartitionedRelPruneInfo *pinfo = lfirst(l2);
-
-				pinfo->rtindex += rtoffset;
-				pinfo->initial_pruning_steps =
-					fix_scan_list(root, pinfo->initial_pruning_steps,
-								  rtoffset, 1);
-				pinfo->exec_pruning_steps =
-					fix_scan_list(root, pinfo->exec_pruning_steps,
-								  rtoffset, 1);
-			}
-		}
-	}
+	/*
+	 * Add PartitionPruneInfo, if any, to PlannerGlobal and update the index.
+	 * Also update the RT indexes present in it to add the offset.
+	 */
+	if (mplan->part_prune_index >= 0)
+		mplan->part_prune_index =
+			register_partpruneinfo(root, mplan->part_prune_index, rtoffset);
 
 	/* We don't need to recurse to lefttree or righttree ... */
 	Assert(mplan->plan.lefttree == NULL);

src/backend/partitioning/partprune.c

@@ -207,16 +207,20 @@ static void partkey_datum_from_expr(PartitionPruneContext *context,
 
 /*
  * make_partition_pruneinfo
- *		Builds a PartitionPruneInfo which can be used in the executor to allow
- *		additional partition pruning to take place.  Returns NULL when
- *		partition pruning would be useless.
+ *		Checks if the given set of quals can be used to build pruning steps
+ *		that the executor can use to prune away unneeded partitions.  If
+ *		suitable quals are found then a PartitionPruneInfo is built and tagged
+ *		onto the PlannerInfo's partPruneInfos list.
+ *
+ * The return value is the 0-based index of the item added to the
+ * partPruneInfos list or -1 if nothing was added.
  *
  * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
  * of scan paths for its child rels.
  * 'prunequal' is a list of potential pruning quals (i.e., restriction
  * clauses that are applicable to the appendrel).
  */
-PartitionPruneInfo *
+int
 make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 						 List *subpaths,
 						 List *prunequal)
@@ -330,10 +334,11 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	 * quals, then we can just not bother with run-time pruning.
 	 */
 	if (prunerelinfos == NIL)
-		return NULL;
+		return -1;
 
 	/* Else build the result data structure */
 	pruneinfo = makeNode(PartitionPruneInfo);
+	pruneinfo->relids = bms_copy(parentrel->relids);
 	pruneinfo->prune_infos = prunerelinfos;
 
 	/*
@@ -356,7 +361,9 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	else
 		pruneinfo->other_subplans = NULL;
 
-	return pruneinfo;
+	root->partPruneInfos = lappend(root->partPruneInfos, pruneinfo);
+
+	return list_length(root->partPruneInfos) - 1;
 }
 
 /*

src/include/executor/execPartition.h

@@ -123,7 +123,8 @@ typedef struct PartitionPruneState
 
 extern PartitionPruneState *ExecInitPartitionPruning(PlanState *planstate,
 													 int n_total_subplans,
-													 PartitionPruneInfo *pruneinfo,
+													 int part_prune_index,
+													 Bitmapset *relids,
 													 Bitmapset **initially_valid_subplans);
 extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
 										   bool initial_prune);

src/include/nodes/execnodes.h

@@ -655,6 +655,7 @@ typedef struct EState
 										 * ExecRowMarks, or NULL if none */
 	List	   *es_rteperminfos;	/* List of RTEPermissionInfo */
 	PlannedStmt *es_plannedstmt;	/* link to top of plan tree */
+	List	   *es_part_prune_infos;	/* List of PartitionPruneInfo */
 	const char *es_sourceText;	/* Source text from QueryDesc */
 
 	JunkFilter *es_junkFilter;	/* top-level junk filter, if any */

src/include/nodes/pathnodes.h

@@ -128,6 +128,9 @@ typedef struct PlannerGlobal
 	/* "flat" list of AppendRelInfos */
 	List	   *appendRelations;
 
+	/* "flat" list of PartitionPruneInfos */
+	List	   *partPruneInfos;
+
 	/* OIDs of relations the plan depends on */
 	List	   *relationOids;
 
@@ -559,6 +562,9 @@ struct PlannerInfo
 
 	/* Does this query modify any partition key columns? */
 	bool		partColsUpdated;
+
+	/* PartitionPruneInfos added in this query's plan. */
+	List	   *partPruneInfos;
 };
 
 

src/include/nodes/plannodes.h

@@ -69,6 +69,9 @@ typedef struct PlannedStmt
 
 	struct Plan *planTree;		/* tree of Plan nodes */
 
+	List	   *partPruneInfos; /* List of PartitionPruneInfo contained in the
+								 * plan */
+
 	List	   *rtable;			/* list of RangeTblEntry nodes */
 
 	List	   *permInfos;		/* list of RTEPermissionInfo nodes for rtable
@@ -278,8 +281,8 @@ typedef struct Append
 	 */
 	int			first_partial_plan;
 
-	/* Info for run-time subplan pruning; NULL if we're not doing that */
-	struct PartitionPruneInfo *part_prune_info;
+	/* Index to PlannerInfo.partPruneInfos or -1 if no run-time pruning */
+	int			part_prune_index;
 } Append;
 
 /* ----------------
@@ -313,8 +316,8 @@ typedef struct MergeAppend
 	/* NULLS FIRST/LAST directions */
 	bool	   *nullsFirst pg_node_attr(array_size(numCols));
 
-	/* Info for run-time subplan pruning; NULL if we're not doing that */
-	struct PartitionPruneInfo *part_prune_info;
+	/* Index to PlannerInfo.partPruneInfos or -1 if no run-time pruning */
+	int			part_prune_index;
 } MergeAppend;
 
 /* ----------------
@@ -1413,6 +1416,10 @@ typedef struct PlanRowMark
  * Then, since an Append-type node could have multiple partitioning
  * hierarchies among its children, we have an unordered List of those Lists.
  *
+ * relids				RelOptInfo.relids of the parent plan node (e.g. Append
+ *						or MergeAppend) to which this PartitionPruneInfo node
+ *						belongs.  The pruning logic ensures that this matches
+ *						the parent plan node's apprelids.
  * prune_infos			List of Lists containing PartitionedRelPruneInfo nodes,
  *						one sublist per run-time-prunable partition hierarchy
  *						appearing in the parent plan node's subplans.
@@ -1425,6 +1432,7 @@ typedef struct PartitionPruneInfo
 	pg_node_attr(no_equal, no_query_jumble)
 
 	NodeTag		type;
+	Bitmapset  *relids;
 	List	   *prune_infos;
 	Bitmapset  *other_subplans;
 } PartitionPruneInfo;

src/include/partitioning/partprune.h

@@ -70,7 +70,7 @@ typedef struct PartitionPruneContext
 #define PruneCxtStateIdx(partnatts, step_id, keyno) \
 	((partnatts) * (step_id) + (keyno))
 
-extern PartitionPruneInfo *make_partition_pruneinfo(struct PlannerInfo *root,
+extern int	make_partition_pruneinfo(struct PlannerInfo *root,
 									 struct RelOptInfo *parentrel,
 									 List *subpaths,
 									 List *prunequal);