Support run-time partition pruning for hash join

From 67c8b0096986444e4402661a74c362448e22a6d4 Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Mon, 14 Aug 2023 14:55:26 +0800
Subject: [PATCH v2] Support run-time partition pruning for hash join

If we have a hash join with an Append node on the outer side, something
like

 Hash Join
   Hash Cond: (pt.a = t.a)
   ->  Append
         ->  Seq Scan on pt_p1 pt_1
         ->  Seq Scan on pt_p2 pt_2
         ->  Seq Scan on pt_p3 pt_3
   ->  Hash
         ->  Seq Scan on t

We can actually prune those subnodes of the Append that cannot possibly
contain any matching tuples from the other side of the join.  To do
that, when building the Hash table, for each row from the inner side we
can compute the minimum set of subnodes that can possibly match the join
condition.  When we have built the Hash table and start to execute the
Append node, we should have known which subnodes are survived and thus
can skip other subnodes.

This patch implements this idea.
---
 src/backend/commands/explain.c                |  61 ++++
 src/backend/executor/execPartition.c          | 127 +++++++-
 src/backend/executor/nodeAppend.c             |  32 +-
 src/backend/executor/nodeHash.c               |  75 +++++
 src/backend/executor/nodeHashjoin.c           |  10 +
 src/backend/executor/nodeMergeAppend.c        |  22 +-
 src/backend/optimizer/path/costsize.c         | 106 +++++++
 src/backend/optimizer/plan/createplan.c       |  49 ++-
 src/backend/optimizer/plan/setrefs.c          |  61 ++++
 src/backend/partitioning/partprune.c          | 288 ++++++++++++++++--
 src/include/executor/execPartition.h          |  17 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/pathnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |  30 ++
 src/include/optimizer/cost.h                  |   4 +
 src/include/partitioning/partprune.h          |  12 +-
 src/test/regress/expected/partition_prune.out |  67 ++++
 src/test/regress/sql/partition_prune.sql      |  18 ++
 18 files changed, 936 insertions(+), 49 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 8570b14f62..e244c93ff5 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -18,6 +18,7 @@
 #include "commands/createas.h"
 #include "commands/defrem.h"
 #include "commands/prepare.h"
+#include "executor/execPartition.h"
 #include "executor/nodeHash.h"
 #include "foreign/fdwapi.h"
 #include "jit/jit.h"
@@ -118,6 +119,9 @@ static void show_instrumentation_count(const char *qlabel, int which,
 									   PlanState *planstate, ExplainState *es);
 static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
 static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
+static void show_join_pruning_result_info(Bitmapset *join_prune_paramids,
+										  ExplainState *es);
+static void show_joinpartprune_info(HashState *hashstate, ExplainState *es);
 static const char *explain_get_index_name(Oid indexId);
 static void show_buffer_usage(ExplainState *es, const BufferUsage *usage,
 							  bool planning);
@@ -2049,9 +2053,17 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			show_incremental_sort_info(castNode(IncrementalSortState, planstate),
 									   es);
 			break;
+		case T_Append:
+			if (es->verbose)
+				show_join_pruning_result_info(((Append *) plan)->join_prune_paramids,
+											  es);
+			break;
 		case T_MergeAppend:
 			show_merge_append_keys(castNode(MergeAppendState, planstate),
 								   ancestors, es);
+			if (es->verbose)
+				show_join_pruning_result_info(((MergeAppend *) plan)->join_prune_paramids,
+											  es);
 			break;
 		case T_Result:
 			show_upper_qual((List *) ((Result *) plan)->resconstantqual,
@@ -2067,6 +2079,8 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			break;
 		case T_Hash:
 			show_hash_info(castNode(HashState, planstate), es);
+			if (es->verbose)
+				show_joinpartprune_info(castNode(HashState, planstate), es);
 			break;
 		case T_Memoize:
 			show_memoize_info(castNode(MemoizeState, planstate), ancestors,
@@ -3507,6 +3521,53 @@ show_eval_params(Bitmapset *bms_params, ExplainState *es)
 		ExplainPropertyList("Params Evaluated", params, es);
 }
 
+/*
+ * Show join partition pruning results at Append/MergeAppend nodes.
+ */
+static void
+show_join_pruning_result_info(Bitmapset *join_prune_paramids, ExplainState *es)
+{
+	int			paramid = -1;
+	List	   *params = NIL;
+
+	if (bms_is_empty(join_prune_paramids))
+		return;
+
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Join Partition Pruning", params, es);
+}
+
+/*
+ * Show join partition pruning infos at Hash nodes.
+ */
+static void
+show_joinpartprune_info(HashState *hashstate, ExplainState *es)
+{
+	List	   *params = NIL;
+	ListCell   *lc;
+
+	if (!hashstate->joinpartprune_state_list)
+		return;
+
+	foreach(lc, hashstate->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", jpstate->paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Partition Prune", params, es);
+}
+
 /*
  * Fetch the name of an index in an EXPLAIN
  *
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index eb8a87fd63..e9121c2a8e 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -199,6 +199,8 @@ static void find_matching_subplans_recurse(PartitionPruningData *prunedata,
 										   PartitionedRelPruningData *pprune,
 										   bool initial_prune,
 										   Bitmapset **validsubplans);
+static bool get_join_prune_matching_subplans(PlanState *planstate,
+											 Bitmapset **partset);
 
 
 /*
@@ -1806,7 +1808,7 @@ ExecInitPartitionPruning(PlanState *planstate,
 	 * Perform an initial partition prune pass, if required.
 	 */
 	if (prunestate->do_initial_prune)
-		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true);
+		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true, NULL);
 	else
 	{
 		/* No pruning, so we'll need to initialize all subplans */
@@ -1836,6 +1838,37 @@ ExecInitPartitionPruning(PlanState *planstate,
 	return prunestate;
 }
 
+/*
+ * ExecInitJoinpartpruneList
+ *		Initialize data structures needed for join partition pruning
+ */
+List *
+ExecInitJoinpartpruneList(PlanState *planstate,
+						  List *joinpartprune_info_list)
+{
+	ListCell   *lc;
+	List	   *result = NIL;
+
+	foreach(lc, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(lc);
+		JoinPartitionPruneState *jpstate = palloc(sizeof(JoinPartitionPruneState));
+
+		jpstate->part_prune_state =
+			CreatePartitionPruneState(planstate, jpinfo->part_prune_info);
+		Assert(jpstate->part_prune_state->do_exec_prune);
+
+		jpstate->paramid = jpinfo->paramid;
+		jpstate->nplans = jpinfo->nplans;
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+
+		result = lappend(result, jpstate);
+	}
+
+	return result;
+}
+
 /*
  * CreatePartitionPruneState
  *		Build the data structure required for calling ExecFindMatchingSubPlans
@@ -2268,7 +2301,9 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
 /*
  * ExecFindMatchingSubPlans
  *		Determine which subplans match the pruning steps detailed in
- *		'prunestate' for the current comparison expression values.
+ *		'prunestate' if any for the current comparison expression values, and
+ *		meanwhile match the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.
  *
  * Pass initial_prune if PARAM_EXEC Params cannot yet be evaluated.  This
  * differentiates the initial executor-time pruning step from later
@@ -2276,11 +2311,30 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
  */
 Bitmapset *
 ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-						 bool initial_prune)
+						 bool initial_prune,
+						 PlanState *planstate)
 {
 	Bitmapset  *result = NULL;
 	MemoryContext oldcontext;
 	int			i;
+	Bitmapset  *join_prune_partset = NULL;
+	bool		do_join_prune;
+
+	/* Retrieve the join partition pruning results if any */
+	do_join_prune =
+		get_join_prune_matching_subplans(planstate, &join_prune_partset);
+
+	/*
+	 * Either we're here on partition prune done according to the pruning steps
+	 * detailed in 'prunestate', or we have done join partition prune.
+	 */
+	Assert(do_join_prune || prunestate != NULL);
+
+	/*
+	 * If there is no 'prunestate', then rely entirely on join pruning.
+	 */
+	if (prunestate == NULL)
+		return join_prune_partset;
 
 	/*
 	 * Either we're here on the initial prune done during pruning
@@ -2321,6 +2375,10 @@ ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
 	/* Add in any subplans that partition pruning didn't account for */
 	result = bms_add_members(result, prunestate->other_subplans);
 
+	/* Intersect join partition pruning results */
+	if (do_join_prune)
+		result = bms_intersect(result, join_prune_partset);
+
 	MemoryContextSwitchTo(oldcontext);
 
 	/* Copy result out of the temp context before we reset it */
@@ -2391,3 +2449,66 @@ find_matching_subplans_recurse(PartitionPruningData *prunedata,
 		}
 	}
 }
+
+/*
+ * get_join_prune_matching_subplans
+ *		Retrieve the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.  Return true if we can
+ *		do join partition pruning, otherwise return false.
+ *
+ * Adds valid (non-prunable) subplan IDs to *partset
+ */
+static bool
+get_join_prune_matching_subplans(PlanState *planstate, Bitmapset **partset)
+{
+	Bitmapset  *join_prune_paramids;
+	int			nplans;
+	int			paramid;
+
+	if (planstate == NULL)
+		return false;
+
+	if (IsA(planstate, AppendState))
+	{
+		join_prune_paramids =
+			((Append *) planstate->plan)->join_prune_paramids;
+		nplans = ((AppendState *) planstate)->as_nplans;
+	}
+	else if (IsA(planstate, MergeAppendState))
+	{
+		join_prune_paramids =
+			((MergeAppend *) planstate->plan)->join_prune_paramids;
+		nplans = ((MergeAppendState *) planstate)->ms_nplans;
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(planstate));
+		return false;
+	}
+
+	if (bms_is_empty(join_prune_paramids))
+		return false;
+
+	Assert(nplans > 0);
+	*partset = bms_add_range(NULL, 0, nplans - 1);
+
+	paramid = -1;
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		ParamExecData *param;
+		JoinPartitionPruneState *jpstate;
+
+		param = &(planstate->state->es_param_exec_vals[paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		jpstate = (JoinPartitionPruneState *) DatumGetPointer(param->value);
+
+		if (jpstate != NULL)
+			*partset = bms_intersect(*partset, jpstate->part_prune_result);
+		else	/* the Hash node for this pruning has not been executed */
+			elog(WARNING, "Join partition pruning $%d has not been performed yet.",
+				 paramid);
+	}
+
+	return true;
+}
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 609df6b9e6..c8dd8583d2 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -151,11 +151,13 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill as_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill as_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 		{
 			appendstate->as_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 			appendstate->as_valid_subplans_identified = true;
@@ -170,10 +172,18 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		appendstate->as_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
-		appendstate->as_valid_subplans_identified = true;
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		appendstate->as_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill as_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+		{
+			appendstate->as_valid_subplans = validsubplans;
+			appendstate->as_valid_subplans_identified = true;
+		}
 	}
 
 	/*
@@ -580,7 +590,7 @@ choose_next_subplan_locally(AppendState *node)
 		else if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 		}
 
@@ -647,7 +657,7 @@ choose_next_subplan_for_leader(AppendState *node)
 		if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 
 			/*
@@ -723,7 +733,7 @@ choose_next_subplan_for_worker(AppendState *node)
 	else if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		mark_invalid_subplans_as_finished(node);
@@ -876,7 +886,7 @@ ExecAppendAsyncBegin(AppendState *node)
 	if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		classify_matching_subplans(node);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 8b5c35b82b..768ca8bf61 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -31,6 +31,7 @@
 #include "catalog/pg_statistic.h"
 #include "commands/tablespace.h"
 #include "executor/execdebug.h"
+#include "executor/execPartition.h"
 #include "executor/hashjoin.h"
 #include "executor/nodeHash.h"
 #include "executor/nodeHashjoin.h"
@@ -48,6 +49,8 @@ static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable);
+static void ExecJoinPartitionPrune(HashState *node);
+static void ExecStoreJoinPartitionPruneResult(HashState *node);
 static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node,
 								  int mcvsToUse);
 static void ExecHashSkewTableInsert(HashJoinTable hashtable,
@@ -189,8 +192,14 @@ MultiExecPrivateHash(HashState *node)
 			}
 			hashtable->totalTuples += 1;
 		}
+
+		/* Perform join partition pruning */
+		ExecJoinPartitionPrune(node);
 	}
 
+	/* Store the surviving partitions for Append/MergeAppend nodes */
+	ExecStoreJoinPartitionPruneResult(node);
+
 	/* resize the hash table if needed (NTUP_PER_BUCKET exceeded) */
 	if (hashtable->nbuckets != hashtable->nbuckets_optimal)
 		ExecHashIncreaseNumBuckets(hashtable);
@@ -401,6 +410,12 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	hashstate->hashkeys =
 		ExecInitExprList(node->hashkeys, (PlanState *) hashstate);
 
+	/*
+	 * initialize join partition pruning infos
+	 */
+	hashstate->joinpartprune_state_list =
+		ExecInitJoinpartpruneList(&hashstate->ps, node->joinpartprune_info_list);
+
 	return hashstate;
 }
 
@@ -1606,6 +1621,56 @@ ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable)
 	}
 }
 
+/*
+ * ExecJoinPartitionPrune
+ *		Perform join partition pruning at this join for each
+ *		JoinPartitionPruneState.
+ */
+static void
+ExecJoinPartitionPrune(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		Bitmapset	   *matching_subPlans;
+
+		if (jpstate->finished)
+			continue;
+
+		matching_subPlans =
+			ExecFindMatchingSubPlans(jpstate->part_prune_state, false, NULL);
+		jpstate->part_prune_result =
+			bms_add_members(jpstate->part_prune_result, matching_subPlans);
+
+		if (bms_num_members(jpstate->part_prune_result) == jpstate->nplans)
+			jpstate->finished = true;
+	}
+}
+
+/*
+ * ExecStoreJoinPartitionPruneResult
+ *		For each JoinPartitionPruneState, store the set of surviving partitions
+ *		to make it available for the Append/MergeAppend node.
+ */
+static void
+ExecStoreJoinPartitionPruneResult(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		ParamExecData	   *param;
+
+		param = &(node->ps.state->es_param_exec_vals[jpstate->paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		param->value = PointerGetDatum(jpstate);
+	}
+}
+
 /*
  * ExecHashTableInsert
  *		insert a tuple into the hash table depending on the hash value
@@ -2350,6 +2415,16 @@ void
 ExecReScanHash(HashState *node)
 {
 	PlanState  *outerPlan = outerPlanState(node);
+	ListCell   *lc;
+
+	/* reset the state in JoinPartitionPruneStates */
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+	}
 
 	/*
 	 * if chgParam of subnode is not null then plan will be re-scanned by
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 980746128b..ec9a660635 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -311,6 +311,16 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 					 */
 					node->hj_FirstOuterTupleSlot = NULL;
 				}
+				else if (hashNode->joinpartprune_state_list != NIL)
+				{
+					/*
+					 * Give the hash node a chance to run join partition
+					 * pruning if there is any JoinPartitionPruneState that can
+					 * be evaluated at it.  So do not apply the empty-outer
+					 * optimization in this case.
+					 */
+					node->hj_FirstOuterTupleSlot = NULL;
+				}
 				else if (HJ_FILL_OUTER(node) ||
 						 (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
 						  !node->hj_OuterNotEmpty))
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 21b5726e6e..9eb276abc8 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -99,11 +99,13 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill ms_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill ms_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 			mergestate->ms_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 	}
 	else
@@ -115,9 +117,15 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		mergestate->ms_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		mergestate->ms_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill ms_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+			mergestate->ms_valid_subplans = validsubplans;
 	}
 
 	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
@@ -218,7 +226,7 @@ ExecMergeAppend(PlanState *pstate)
 		 */
 		if (node->ms_valid_subplans == NULL)
 			node->ms_valid_subplans =
-				ExecFindMatchingSubPlans(node->ms_prune_state, false);
+				ExecFindMatchingSubPlans(node->ms_prune_state, false, &node->ps);
 
 		/*
 		 * First time through: pull the first tuple from each valid subplan,
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index d6ceafd51c..9bdc88a9db 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -173,6 +173,10 @@ static void get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
 static bool has_indexed_join_quals(NestPath *path);
 static double approx_tuple_count(PlannerInfo *root, JoinPath *path,
 								 List *quals);
+static double get_joinrel_matching_outer_size(PlannerInfo *root,
+											  RelOptInfo *outer_rel,
+											  Relids inner_relids,
+											  List *restrictlist);
 static double calc_joinrel_size_estimate(PlannerInfo *root,
 										 RelOptInfo *joinrel,
 										 RelOptInfo *outer_rel,
@@ -5380,6 +5384,61 @@ get_parameterized_joinrel_size(PlannerInfo *root, RelOptInfo *rel,
 	return nrows;
 }
 
+/*
+ * get_joinrel_matching_outer_size
+ *		Make a size estimate for the outer side that matches the inner side.
+ */
+static double
+get_joinrel_matching_outer_size(PlannerInfo *root,
+								RelOptInfo *outer_rel,
+								Relids inner_relids,
+								List *restrictlist)
+{
+	double		nrows;
+	Selectivity fkselec;
+	Selectivity jselec;
+	SpecialJoinInfo *sjinfo;
+	SpecialJoinInfo sjinfo_data;
+
+	sjinfo = &sjinfo_data;
+	sjinfo->type = T_SpecialJoinInfo;
+	sjinfo->min_lefthand = outer_rel->relids;
+	sjinfo->min_righthand = inner_relids;
+	sjinfo->syn_lefthand = outer_rel->relids;
+	sjinfo->syn_righthand = inner_relids;
+	sjinfo->jointype = JOIN_SEMI;
+	sjinfo->ojrelid = 0;
+	sjinfo->commute_above_l = NULL;
+	sjinfo->commute_above_r = NULL;
+	sjinfo->commute_below_l = NULL;
+	sjinfo->commute_below_r = NULL;
+	/* we don't bother trying to make the remaining fields valid */
+	sjinfo->lhs_strict = false;
+	sjinfo->semi_can_btree = false;
+	sjinfo->semi_can_hash = false;
+	sjinfo->semi_operators = NIL;
+	sjinfo->semi_rhs_exprs = NIL;
+
+	fkselec = get_foreign_key_join_selectivity(root,
+											   outer_rel->relids,
+											   inner_relids,
+											   sjinfo,
+											   &restrictlist);
+	jselec = clauselist_selectivity(root,
+									restrictlist,
+									0,
+									sjinfo->jointype,
+									sjinfo);
+
+	nrows = outer_rel->rows * fkselec * jselec;
+	nrows = clamp_row_est(nrows);
+
+	/* For safety, make sure result is not more than the base estimate */
+	if (nrows > outer_rel->rows)
+		nrows = outer_rel->rows;
+	return nrows;
+}
+
 /*
  * calc_joinrel_size_estimate
  *		Workhorse for set_joinrel_size_estimates and
@@ -6495,3 +6554,50 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel, Path *bitmapqual,
 
 	return pages_fetched;
 }
+
+/*
+ * compute_partprune_cost
+ *		Compute the overhead of join partition pruning.
+ */
+double
+compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+					   Cost append_total_cost, int append_nplans,
+					   Relids inner_relids, double inner_rows,
+					   List *prunequal)
+{
+	Cost		prune_cost;
+	Cost		saved_cost;
+	double		matching_outer_rows;
+	double		unmatched_nplans;
+
+	switch (appendrel->part_scheme->strategy)
+	{
+
+		case PARTITION_STRATEGY_LIST:
+		case PARTITION_STRATEGY_RANGE:
+			prune_cost = cpu_operator_cost * LOG2(append_nplans) * inner_rows;
+			break;
+		case PARTITION_STRATEGY_HASH:
+			prune_cost = cpu_operator_cost * append_nplans * inner_rows;
+			break;
+		default:
+			elog(ERROR, "unexpected partition strategy: %d",
+				 (int) appendrel->part_scheme->strategy);
+			break;
+	}
+
+	matching_outer_rows =
+		get_joinrel_matching_outer_size(root,
+										appendrel,
+										inner_relids,
+										prunequal);
+
+	/*
+	 * We assume that each outer joined row occupies one new partition.  This
+	 * is really the worst case.
+	 */
+	unmatched_nplans = append_nplans - Min(matching_outer_rows, append_nplans);
+	saved_cost = (unmatched_nplans / append_nplans) * append_total_cost;
+
+	return prune_cost - saved_cost;
+}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 34ca6d4ac2..308ff452d3 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -242,7 +242,8 @@ static Hash *make_hash(Plan *lefttree,
 					   List *hashkeys,
 					   Oid skewTable,
 					   AttrNumber skewColumn,
-					   bool skewInherit);
+					   bool skewInherit,
+					   List *joinpartprune_info_list);
 static MergeJoin *make_mergejoin(List *tlist,
 								 List *joinclauses, List *otherclauses,
 								 List *mergeclauses,
@@ -342,6 +343,7 @@ create_plan(PlannerInfo *root, Path *best_path)
 	/* Initialize this module's workspace in PlannerInfo */
 	root->curOuterRels = NULL;
 	root->curOuterParams = NIL;
+	root->join_partition_prune_candidates = NIL;
 
 	/* Recursively process the path tree, demanding the correct tlist result */
 	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
@@ -369,6 +371,8 @@ create_plan(PlannerInfo *root, Path *best_path)
 	if (root->curOuterParams != NIL)
 		elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
 
+	Assert(root->join_partition_prune_candidates == NIL);
+
 	/*
 	 * Reset plan_params to ensure param IDs used for nestloop params are not
 	 * re-used later
@@ -1223,6 +1227,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	int			nasyncplans = 0;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 	int			nodenumsortkeys = 0;
 	AttrNumber *nodeSortColIdx = NULL;
 	Oid		   *nodeSortOperators = NULL;
@@ -1377,6 +1382,8 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1399,13 +1406,20 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 			partpruneinfo =
 				make_partition_pruneinfo(root, rel,
 										 best_path->subpaths,
-										 prunequal);
+										 prunequal,
+										 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	plan->appendplans = subplans;
 	plan->nasyncplans = nasyncplans;
 	plan->first_partial_plan = best_path->first_partial_path;
 	plan->part_prune_info = partpruneinfo;
+	plan->join_prune_paramids = join_prune_paramids;
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -1445,6 +1459,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	ListCell   *subpaths;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 
 	/*
 	 * We don't have the actual creation of the MergeAppend node split out
@@ -1541,6 +1556,8 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1554,11 +1571,18 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		if (prunequal != NIL)
 			partpruneinfo = make_partition_pruneinfo(root, rel,
 													 best_path->subpaths,
-													 prunequal);
+													 prunequal,
+													 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	node->mergeplans = subplans;
 	node->part_prune_info = partpruneinfo;
+	node->join_prune_paramids = join_prune_paramids;
 
 	/*
 	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
@@ -4734,6 +4758,13 @@ create_hashjoin_plan(PlannerInfo *root,
 	AttrNumber	skewColumn = InvalidAttrNumber;
 	bool		skewInherit = false;
 	ListCell   *lc;
+	List	   *joinpartprune_info_list;
+
+	/*
+	 * Collect information required to build JoinPartitionPruneInfos at this
+	 * join.
+	 */
+	prepare_join_partition_prune_candidate(root, &best_path->jpath);
 
 	/*
 	 * HashJoin can project, so we don't have to demand exact tlists from the
@@ -4745,6 +4776,11 @@ create_hashjoin_plan(PlannerInfo *root,
 	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
 									 (best_path->num_batches > 1) ? CP_SMALL_TLIST : 0);
 
+	/*
+	 * Retrieve all the JoinPartitionPruneInfos for this join.
+	 */
+	joinpartprune_info_list = get_join_partition_prune_candidate(root);
+
 	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
 									 CP_SMALL_TLIST);
 
@@ -4850,7 +4886,8 @@ create_hashjoin_plan(PlannerInfo *root,
 						  inner_hashkeys,
 						  skewTable,
 						  skewColumn,
-						  skewInherit);
+						  skewInherit,
+						  joinpartprune_info_list);
 
 	/*
 	 * Set Hash node's startup & total costs equal to total cost of input
@@ -5977,7 +6014,8 @@ make_hash(Plan *lefttree,
 		  List *hashkeys,
 		  Oid skewTable,
 		  AttrNumber skewColumn,
-		  bool skewInherit)
+		  bool skewInherit,
+		  List *joinpartprune_info_list)
 {
 	Hash	   *node = makeNode(Hash);
 	Plan	   *plan = &node->plan;
@@ -5991,6 +6029,7 @@ make_hash(Plan *lefttree,
 	node->skewTable = skewTable;
 	node->skewColumn = skewColumn;
 	node->skewInherit = skewInherit;
+	node->joinpartprune_info_list = joinpartprune_info_list;
 
 	return node;
 }
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 97fa561e4e..7013f7f656 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -156,6 +156,11 @@ static Plan *set_mergeappend_references(PlannerInfo *root,
 										MergeAppend *mplan,
 										int rtoffset);
 static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_joinpartitionprune_references(PlannerInfo *root,
+											  List *joinpartprune_info_list,
+											  indexed_tlist *outer_itlist,
+											  int rtoffset,
+											  double num_exec);
 static Relids offset_relid_set(Relids relids, int rtoffset);
 static Node *fix_scan_expr(PlannerInfo *root, Node *node,
 						   int rtoffset, double num_exec);
@@ -1897,6 +1902,62 @@ set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset)
 
 	/* Hash nodes don't have their own quals */
 	Assert(plan->qual == NIL);
+
+	set_joinpartitionprune_references(root,
+									  hplan->joinpartprune_info_list,
+									  outer_itlist,
+									  rtoffset,
+									  NUM_EXEC_TLIST(plan));
+}
+
+/*
+ * set_joinpartitionprune_references
+ *	   Do set_plan_references processing on JoinPartitionPruneInfos
+ */
+static void
+set_joinpartitionprune_references(PlannerInfo *root,
+								  List *joinpartprune_info_list,
+								  indexed_tlist *outer_itlist,
+								  int rtoffset,
+								  double num_exec)
+{
+	ListCell   *l;
+
+	foreach(l, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(l);
+		ListCell   *l1;
+
+		foreach(l1, jpinfo->part_prune_info->prune_infos)
+		{
+			List	   *prune_infos = lfirst(l1);
+			ListCell   *l2;
+
+			foreach(l2, prune_infos)
+			{
+				PartitionedRelPruneInfo *pinfo = lfirst(l2);
+
+				pinfo->rtindex += rtoffset;
+
+				pinfo->initial_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->initial_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+				pinfo->exec_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->exec_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+			}
+		}
+	}
 }
 
 /*
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 7179b22a05..b8bacfd22b 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -48,7 +48,9 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/cost.h"
 #include "optimizer/optimizer.h"
+#include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/restrictinfo.h"
 #include "parser/parsetree.h"
 #include "partitioning/partbounds.h"
 #include "partitioning/partprune.h"
@@ -103,15 +105,16 @@ typedef enum PartClauseTarget
  *
  * gen_partprune_steps() initializes and returns an instance of this struct.
  *
- * Note that has_mutable_op, has_mutable_arg, and has_exec_param are set if
- * we found any potentially-useful-for-pruning clause having those properties,
- * whether or not we actually used the clause in the steps list.  This
- * definition allows us to skip the PARTTARGET_EXEC pass in some cases.
+ * Note that has_mutable_op, has_mutable_arg, has_exec_param and has_vars are
+ * set if we found any potentially-useful-for-pruning clause having those
+ * properties, whether or not we actually used the clause in the steps list.
+ * This definition allows us to skip the PARTTARGET_EXEC pass in some cases.
  */
 typedef struct GeneratePruningStepsContext
 {
 	/* Copies of input arguments for gen_partprune_steps: */
 	RelOptInfo *rel;			/* the partitioned relation */
+	Bitmapset  *available_rels;	/* rels whose Vars may be used for pruning */
 	PartClauseTarget target;	/* use-case we're generating steps for */
 	/* Result data: */
 	List	   *steps;			/* list of PartitionPruneSteps */
@@ -119,6 +122,7 @@ typedef struct GeneratePruningStepsContext
 	bool		has_mutable_arg;	/* clauses include any mutable comparison
 									 * values, *other than* exec params */
 	bool		has_exec_param; /* clauses include any PARAM_EXEC params */
+	bool		has_vars;		/* clauses include any Vars from 'available_rels' */
 	bool		contradictory;	/* clauses were proven self-contradictory */
 	/* Working state: */
 	int			next_step_id;
@@ -144,8 +148,10 @@ static List *make_partitionedrel_pruneinfo(PlannerInfo *root,
 										   List *prunequal,
 										   Bitmapset *partrelids,
 										   int *relid_subplan_map,
+										   Bitmapset *available_rels,
 										   Bitmapset **matchedsubplans);
 static void gen_partprune_steps(RelOptInfo *rel, List *clauses,
+								Bitmapset *available_rels,
 								PartClauseTarget target,
 								GeneratePruningStepsContext *context);
 static List *gen_partprune_steps_internal(GeneratePruningStepsContext *context,
@@ -206,6 +212,10 @@ static PartClauseMatchStatus match_boolean_partition_clause(Oid partopfamily,
 static void partkey_datum_from_expr(PartitionPruneContext *context,
 									Expr *expr, int stateidx,
 									Datum *value, bool *isnull);
+static bool contain_forbidden_var_clause(Node *node,
+										 GeneratePruningStepsContext *context);
+static bool contain_forbidden_var_clause_walker(Node *node,
+												GeneratePruningStepsContext *context);
 
 
 /*
@@ -218,11 +228,14 @@ static void partkey_datum_from_expr(PartitionPruneContext *context,
  * 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).
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
  */
 PartitionPruneInfo *
 make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 						 List *subpaths,
-						 List *prunequal)
+						 List *prunequal,
+						 Bitmapset *available_rels)
 {
 	PartitionPruneInfo *pruneinfo;
 	Bitmapset  *allmatchedsubplans = NULL;
@@ -315,6 +328,7 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 												  prunequal,
 												  partrelids,
 												  relid_subplan_map,
+												  available_rels,
 												  &matchedsubplans);
 
 		/* When pruning is possible, record the matched subplans */
@@ -362,6 +376,174 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	return pruneinfo;
 }
 
+/*
+ * make_join_partition_pruneinfos
+ *		Builds one JoinPartitionPruneInfo for each join at which join partition
+ *		pruning is possible for this appendrel.
+ *
+ * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
+ * of scan paths for its child rels.
+ */
+Bitmapset *
+make_join_partition_pruneinfos(PlannerInfo *root, RelOptInfo *parentrel,
+							   Path *best_path, List *subpaths)
+{
+	Bitmapset  *result = NULL;
+	ListCell   *lc;
+
+	if (!IS_PARTITIONED_REL(parentrel))
+		return NULL;
+
+	foreach(lc, root->join_partition_prune_candidates)
+	{
+		JoinPartitionPruneCandidateInfo *candidate =
+			(JoinPartitionPruneCandidateInfo *) lfirst(lc);
+		PartitionPruneInfo *part_prune_info;
+		List	   *prunequal;
+		Relids		joinrelids;
+		ListCell   *l;
+		double		prune_cost;
+
+		if (candidate == NULL)
+			continue;
+
+		/*
+		 * Identify all joinclauses that are movable to this appendrel given
+		 * this inner side relids.  Only those clauses can be used for join
+		 * partition pruning.
+		 */
+		joinrelids = bms_union(parentrel->relids, candidate->inner_relids);
+		prunequal = NIL;
+		foreach(l, candidate->joinrestrictinfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+
+			if (join_clause_is_movable_into(rinfo,
+											parentrel->relids,
+											joinrelids))
+				prunequal = lappend(prunequal, rinfo);
+		}
+
+		if (prunequal == NIL)
+			continue;
+
+		/*
+		 * Check the overhead of this pruning
+		 */
+		prune_cost = compute_partprune_cost(root,
+											parentrel,
+											best_path->total_cost,
+											list_length(subpaths),
+											candidate->inner_relids,
+											candidate->inner_rows,
+											prunequal);
+		if (prune_cost > 0)
+			continue;
+
+		part_prune_info = make_partition_pruneinfo(root, parentrel,
+												   subpaths,
+												   prunequal,
+												   candidate->inner_relids);
+
+		if (part_prune_info)
+		{
+			JoinPartitionPruneInfo *jpinfo;
+
+			jpinfo = palloc(sizeof(JoinPartitionPruneInfo));
+
+			jpinfo->part_prune_info = part_prune_info;
+			jpinfo->paramid = assign_special_exec_param(root);
+			jpinfo->nplans = list_length(subpaths);
+
+			candidate->joinpartprune_info_list =
+				lappend(candidate->joinpartprune_info_list, jpinfo);
+
+			result = bms_add_member(result, jpinfo->paramid);
+		}
+	}
+
+	return result;
+}
+
+/*
+ * prepare_join_partition_prune_candidate
+ * 		Check if join partition pruning is possible at this join and if so
+ * 		collect information required to build JoinPartitionPruneInfos.
+ *
+ * Note that we may build more than one JoinPartitionPruneInfo at one join, for
+ * different Append/MergeAppend paths.
+ */
+void
+prepare_join_partition_prune_candidate(PlannerInfo *root, JoinPath *jpath)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+
+	if (!enable_partition_pruning)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * We cannot perform join partition pruning if the outer is the
+	 * non-nullable side.
+	 */
+	if (!(jpath->jointype == JOIN_INNER ||
+		  jpath->jointype == JOIN_SEMI ||
+		  jpath->jointype == JOIN_RIGHT ||
+		  jpath->jointype == JOIN_RIGHT_ANTI))
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now we only support HashJoin.
+	 */
+	if (jpath->path.pathtype != T_HashJoin)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	candidate = palloc(sizeof(JoinPartitionPruneCandidateInfo));
+	candidate->joinrestrictinfo = jpath->joinrestrictinfo;
+	candidate->inner_relids = jpath->innerjoinpath->parent->relids;
+	candidate->inner_rows = jpath->innerjoinpath->parent->rows;
+	candidate->joinpartprune_info_list = NIL;
+
+	root->join_partition_prune_candidates =
+		lappend(root->join_partition_prune_candidates, candidate);
+}
+
+/*
+ * get_join_partition_prune_candidate
+ *		Pop out the JoinPartitionPruneCandidateInfo for this join and retrieve
+ *		the JoinPartitionPruneInfos.
+ */
+List *
+get_join_partition_prune_candidate(PlannerInfo *root)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+	List   *result;
+
+	candidate = llast(root->join_partition_prune_candidates);
+	root->join_partition_prune_candidates =
+		list_delete_last(root->join_partition_prune_candidates);
+
+	if (candidate == NULL)
+		return NIL;
+
+	result = candidate->joinpartprune_info_list;
+
+	pfree(candidate);
+
+	return result;
+}
+
 /*
  * add_part_relids
  *		Add new info to a list of Bitmapsets of partitioned relids.
@@ -430,6 +612,8 @@ add_part_relids(List *allpartrelids, Bitmapset *partrelids)
  * partrelids: Set of RT indexes identifying relevant partitioned tables
  *   within a single partitioning hierarchy
  * relid_subplan_map[]: maps child relation relids to subplan indexes
+ * available_rels: the relid set of rels whose Vars may be used for
+ *   pruning.
  * matchedsubplans: on success, receives the set of subplan indexes which
  *   were matched to this partition hierarchy
  *
@@ -442,6 +626,7 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 							  List *prunequal,
 							  Bitmapset *partrelids,
 							  int *relid_subplan_map,
+							  Bitmapset *available_rels,
 							  Bitmapset **matchedsubplans)
 {
 	RelOptInfo *targetpart = NULL;
@@ -541,8 +726,8 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 		 * pruning steps and detects whether there's any possibly-useful quals
 		 * that would require per-scan pruning.
 		 */
-		gen_partprune_steps(subpart, partprunequal, PARTTARGET_INITIAL,
-							&context);
+		gen_partprune_steps(subpart, partprunequal, available_rels,
+							PARTTARGET_INITIAL, &context);
 
 		if (context.contradictory)
 		{
@@ -569,14 +754,15 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			initial_pruning_steps = NIL;
 
 		/*
-		 * If no exec Params appear in potentially-usable pruning clauses,
-		 * then there's no point in even thinking about per-scan pruning.
+		 * If no exec Params or available Vars appear in potentially-usable
+		 * pruning clauses, then there's no point in even thinking about
+		 * per-scan pruning.
 		 */
-		if (context.has_exec_param)
+		if (context.has_exec_param || context.has_vars)
 		{
 			/* ... OK, we'd better think about it */
-			gen_partprune_steps(subpart, partprunequal, PARTTARGET_EXEC,
-								&context);
+			gen_partprune_steps(subpart, partprunequal, available_rels,
+								PARTTARGET_EXEC, &context);
 
 			if (context.contradictory)
 			{
@@ -589,11 +775,14 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			/*
 			 * Detect which exec Params actually got used; the fact that some
 			 * were in available clauses doesn't mean we actually used them.
-			 * Skip per-scan pruning if there are none.
 			 */
 			execparamids = get_partkey_exec_paramids(exec_pruning_steps);
 
-			if (bms_is_empty(execparamids))
+			/*
+			 * Skip per-scan pruning if there are none used exec Params and
+			 * there are none available Vars.
+			 */
+			if (bms_is_empty(execparamids) && !context.has_vars)
 				exec_pruning_steps = NIL;
 		}
 		else
@@ -705,6 +894,9 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  *		Process 'clauses' (typically a rel's baserestrictinfo list of clauses)
  *		and create a list of "partition pruning steps".
  *
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
+ *
  * 'target' tells whether to generate pruning steps for planning (use
  * immutable clauses only), or for executor startup (use any allowable
  * clause except ones containing PARAM_EXEC Params), or for executor
@@ -714,12 +906,13 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  * some subsidiary flags; see the GeneratePruningStepsContext typedef.
  */
 static void
-gen_partprune_steps(RelOptInfo *rel, List *clauses, PartClauseTarget target,
-					GeneratePruningStepsContext *context)
+gen_partprune_steps(RelOptInfo *rel, List *clauses, Bitmapset *available_rels,
+					PartClauseTarget target, GeneratePruningStepsContext *context)
 {
 	/* Initialize all output values to zero/false/NULL */
 	memset(context, 0, sizeof(GeneratePruningStepsContext));
 	context->rel = rel;
+	context->available_rels = available_rels;
 	context->target = target;
 
 	/*
@@ -775,7 +968,7 @@ prune_append_rel_partitions(RelOptInfo *rel)
 	 * If the clauses are found to be contradictory, we can return the empty
 	 * set.
 	 */
-	gen_partprune_steps(rel, clauses, PARTTARGET_PLANNER,
+	gen_partprune_steps(rel, clauses, NULL, PARTTARGET_PLANNER,
 						&gcontext);
 	if (gcontext.contradictory)
 		return NULL;
@@ -1962,9 +2155,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) expr))
+			if (contain_forbidden_var_clause((Node *) expr, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -2160,9 +2354,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) rightop))
+			if (contain_forbidden_var_clause((Node *) rightop, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -3712,3 +3907,54 @@ partkey_datum_from_expr(PartitionPruneContext *context,
 		*value = ExecEvalExprSwitchContext(exprstate, ectx, isnull);
 	}
 }
+
+/*
+ * contain_forbidden_var_clause
+ *	  Recursively scan a clause to discover whether it contains any Var nodes
+ *	  (of the current query level) that do not belong to relations in
+ *	  context->available_rels.
+ *
+ *	  Returns true if any such varnode found.
+ *
+ * Does not examine subqueries, therefore must only be used after reduction
+ * of sublinks to subplans!
+ */
+static bool
+contain_forbidden_var_clause(Node *node, GeneratePruningStepsContext *context)
+{
+	return contain_forbidden_var_clause_walker(node, context);
+}
+
+static bool
+contain_forbidden_var_clause_walker(Node *node, GeneratePruningStepsContext *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		*var = (Var *) node;
+
+		if (var->varlevelsup != 0)
+			return false;
+
+		if (!bms_is_member(var->varno, context->available_rels))
+			return true;		/* abort the tree traversal and return true */
+
+		context->has_vars = true;
+
+		if (context->target != PARTTARGET_EXEC)
+			return true;		/* abort the tree traversal and return true */
+
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+		return true;
+	if (IsA(node, PlaceHolderVar))
+	{
+		if (((PlaceHolderVar *) node)->phlevelsup == 0)
+			return true;		/* abort the tree traversal and return true */
+		/* else fall through to check the contained expr */
+	}
+	return expression_tree_walker(node, contain_forbidden_var_clause_walker,
+								  (void *) context);
+}
diff --git a/src/include/executor/execPartition.h b/src/include/executor/execPartition.h
index 15ec869ac8..720bcc1149 100644
--- a/src/include/executor/execPartition.h
+++ b/src/include/executor/execPartition.h
@@ -121,11 +121,26 @@ typedef struct PartitionPruneState
 	PartitionPruningData *partprunedata[FLEXIBLE_ARRAY_MEMBER];
 } PartitionPruneState;
 
+/*
+ * JoinPartitionPruneState - State object required for plan nodes to perform
+ * join partition pruning.
+ */
+typedef struct JoinPartitionPruneState
+{
+	PartitionPruneState *part_prune_state;
+	int			paramid;
+	int			nplans;
+	bool		finished;
+	Bitmapset  *part_prune_result;
+} JoinPartitionPruneState;
+
 extern PartitionPruneState *ExecInitPartitionPruning(PlanState *planstate,
 													 int n_total_subplans,
 													 PartitionPruneInfo *pruneinfo,
 													 Bitmapset **initially_valid_subplans);
+extern List *ExecInitJoinpartpruneList(PlanState *planstate, List *joinpartprune_info_list);
 extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-										   bool initial_prune);
+										   bool initial_prune,
+										   PlanState *planstate);
 
 #endif							/* EXECPARTITION_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index cb714f4a19..9c8440d00c 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2679,6 +2679,9 @@ typedef struct HashState
 
 	/* Parallel hash state. */
 	struct ParallelHashJoinState *parallel_state;
+
+	/* Infos for join partition pruning. */
+	List *joinpartprune_state_list;
 } HashState;
 
 /* ----------------
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 5702fbba60..297a683b4a 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,9 @@ struct PlannerInfo
 	/* not-yet-assigned NestLoopParams */
 	List	   *curOuterParams;
 
+	/* a stack of JoinPartitionPruneInfos */
+	List	   *join_partition_prune_candidates;
+
 	/*
 	 * These fields are workspace for setrefs.c.  Each is an array
 	 * corresponding to glob->subplans.  (We could probably teach
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 1b787fe031..2749206e0b 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -275,6 +275,9 @@ typedef struct Append
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } Append;
 
 /* ----------------
@@ -310,6 +313,9 @@ typedef struct MergeAppend
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } MergeAppend;
 
 /* ----------------
@@ -1206,6 +1212,7 @@ typedef struct Hash
 	bool		skewInherit;	/* is outer join rel an inheritance tree? */
 	/* all other info is in the parent HashJoin node */
 	Cardinality rows_total;		/* estimate total rows if parallel_aware */
+	List	   *joinpartprune_info_list;	/* infos for join partition pruning */
 } Hash;
 
 /* ----------------
@@ -1552,6 +1559,29 @@ typedef struct PartitionPruneStepCombine
 	List	   *source_stepids;
 } PartitionPruneStepCombine;
 
+/*
+ * JoinPartitionPruneCandidateInfo - Information required to build
+ * JoinPartitionPruneInfos.
+ */
+typedef struct JoinPartitionPruneCandidateInfo
+{
+	List	   *joinrestrictinfo;
+	Bitmapset  *inner_relids;
+	double		inner_rows;
+	List	   *joinpartprune_info_list;
+} JoinPartitionPruneCandidateInfo;
+
+/*
+ * JoinPartitionPruneInfo - Details required to allow the executor to prune
+ * partitions during join.
+ */
+typedef struct JoinPartitionPruneInfo
+{
+	PartitionPruneInfo *part_prune_info;
+	int			paramid;
+	int			nplans;
+} JoinPartitionPruneInfo;
+
 
 /*
  * Plan invalidation info
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index bee090ffc2..4ab9accf70 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -211,5 +211,9 @@ extern void set_foreign_size_estimates(PlannerInfo *root, RelOptInfo *rel);
 extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *target);
 extern double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 								   Path *bitmapqual, int loop_count, Cost *cost, double *tuple);
+extern double compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+									 Cost append_total_cost, int append_nplans,
+									 Relids inner_relids, double inner_rows,
+									 List *prunequal);
 
 #endif							/* COST_H */
diff --git a/src/include/partitioning/partprune.h b/src/include/partitioning/partprune.h
index 8636e04e37..899aa61b34 100644
--- a/src/include/partitioning/partprune.h
+++ b/src/include/partitioning/partprune.h
@@ -19,6 +19,8 @@
 
 struct PlannerInfo;				/* avoid including pathnodes.h here */
 struct RelOptInfo;
+struct Path;
+struct JoinPath;
 
 
 /*
@@ -73,7 +75,15 @@ typedef struct PartitionPruneContext
 extern PartitionPruneInfo *make_partition_pruneinfo(struct PlannerInfo *root,
 													struct RelOptInfo *parentrel,
 													List *subpaths,
-													List *prunequal);
+													List *prunequal,
+													Bitmapset *available_rels);
+extern Bitmapset *make_join_partition_pruneinfos(struct PlannerInfo *root,
+												 struct RelOptInfo *parentrel,
+												 struct Path *best_path,
+												 List *subpaths);
+extern void prepare_join_partition_prune_candidate(struct PlannerInfo *root,
+												   struct JoinPath *jpath);
+extern List *get_join_partition_prune_candidate(struct PlannerInfo *root);
 extern Bitmapset *prune_append_rel_partitions(struct RelOptInfo *rel);
 extern Bitmapset *get_matching_partitions(PartitionPruneContext *context,
 										  List *pruning_steps);
diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 1eb347503a..80cc8cdae6 100644
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -2983,6 +2983,73 @@ order by tbl1.col1, tprt.col1;
 ------+------
 (0 rows)
 
+-- join partition pruning
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+explain (analyze, verbose, costs off, summary off, timing off)
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+                                   QUERY PLAN                                   
+--------------------------------------------------------------------------------
+ Hash Right Join (actual rows=2 loops=1)
+   Output: p1.col1, p2.col1, t.col1
+   Hash Cond: ((p1.col1 = t.col1) AND (p2.col1 = t.col1))
+   ->  Hash Join (actual rows=3 loops=1)
+         Output: p1.col1, p2.col1
+         Hash Cond: (p1.col1 = p2.col1)
+         ->  Append (actual rows=3 loops=1)
+               Join Partition Pruning: $0
+               ->  Seq Scan on public.tprt_1 p1_1 (never executed)
+                     Output: p1_1.col1
+               ->  Seq Scan on public.tprt_2 p1_2 (actual rows=3 loops=1)
+                     Output: p1_2.col1
+               ->  Seq Scan on public.tprt_3 p1_3 (never executed)
+                     Output: p1_3.col1
+               ->  Seq Scan on public.tprt_4 p1_4 (never executed)
+                     Output: p1_4.col1
+               ->  Seq Scan on public.tprt_5 p1_5 (never executed)
+                     Output: p1_5.col1
+               ->  Seq Scan on public.tprt_6 p1_6 (never executed)
+                     Output: p1_6.col1
+         ->  Hash (actual rows=3 loops=1)
+               Output: p2.col1
+               Buckets: 1024  Batches: 1  Memory Usage: 9kB
+               ->  Append (actual rows=3 loops=1)
+                     Join Partition Pruning: $1
+                     ->  Seq Scan on public.tprt_1 p2_1 (never executed)
+                           Output: p2_1.col1
+                     ->  Seq Scan on public.tprt_2 p2_2 (actual rows=3 loops=1)
+                           Output: p2_2.col1
+                     ->  Seq Scan on public.tprt_3 p2_3 (never executed)
+                           Output: p2_3.col1
+                     ->  Seq Scan on public.tprt_4 p2_4 (never executed)
+                           Output: p2_4.col1
+                     ->  Seq Scan on public.tprt_5 p2_5 (never executed)
+                           Output: p2_5.col1
+                     ->  Seq Scan on public.tprt_6 p2_6 (never executed)
+                           Output: p2_6.col1
+   ->  Hash (actual rows=2 loops=1)
+         Output: t.col1
+         Buckets: 1024  Batches: 1  Memory Usage: 9kB
+         Partition Prune: $0, $1
+         ->  Seq Scan on public.tbl1 t (actual rows=2 loops=1)
+               Output: t.col1
+(43 rows)
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+ col1 | col1 | col1 
+------+------+------
+  501 |  501 |  501
+  505 |  505 |  505
+(2 rows)
+
 drop table tbl1, tprt;
 -- Test with columns defined in varying orders between each level
 create table part_abc (a int not null, b int not null, c int not null) partition by list (a);
diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index d1c60b8fe9..976a2e2b89 100644
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -710,6 +710,24 @@ select tbl1.col1, tprt.col1 from tbl1
 inner join tprt on tbl1.col1 = tprt.col1
 order by tbl1.col1, tprt.col1;
 
+-- join partition pruning
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+
+explain (analyze, verbose, costs off, summary off, timing off)
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+
 drop table tbl1, tprt;
 
 -- Test with columns defined in varying orders between each level
-- 
2.31.0

From 69602dd1062ea4eeecf0008b34b4fca3617d2620 Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Mon, 14 Aug 2023 14:55:26 +0800
Subject: [PATCH v3] Support run-time partition pruning for hash join

If we have a hash join with an Append node on the outer side, something
like

 Hash Join
   Hash Cond: (pt.a = t.a)
   ->  Append
         ->  Seq Scan on pt_p1 pt_1
         ->  Seq Scan on pt_p2 pt_2
         ->  Seq Scan on pt_p3 pt_3
   ->  Hash
         ->  Seq Scan on t

We can actually prune those subnodes of the Append that cannot possibly
contain any matching tuples from the other side of the join.  To do
that, when building the Hash table, for each row from the inner side we
can compute the minimum set of subnodes that can possibly match the join
condition.  When we have built the Hash table and start to execute the
Append node, we should have known which subnodes are survived and thus
can skip other subnodes.

This patch implements this idea.
---
 src/backend/commands/explain.c                |  61 ++++
 src/backend/executor/execPartition.c          | 127 +++++++-
 src/backend/executor/nodeAppend.c             |  32 +-
 src/backend/executor/nodeHash.c               |  75 +++++
 src/backend/executor/nodeHashjoin.c           |  10 +
 src/backend/executor/nodeMergeAppend.c        |  22 +-
 src/backend/optimizer/path/costsize.c         | 106 +++++++
 src/backend/optimizer/plan/createplan.c       |  49 ++-
 src/backend/optimizer/plan/setrefs.c          |  61 ++++
 src/backend/partitioning/partprune.c          | 288 ++++++++++++++++--
 src/include/executor/execPartition.h          |  17 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/pathnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |  30 ++
 src/include/optimizer/cost.h                  |   4 +
 src/include/partitioning/partprune.h          |  12 +-
 src/test/regress/expected/partition_prune.out |  86 ++++++
 src/test/regress/sql/partition_prune.sql      |  39 +++
 18 files changed, 976 insertions(+), 49 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index f1d71bc54e..c51cf6beb6 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -18,6 +18,7 @@
 #include "commands/createas.h"
 #include "commands/defrem.h"
 #include "commands/prepare.h"
+#include "executor/execPartition.h"
 #include "executor/nodeHash.h"
 #include "foreign/fdwapi.h"
 #include "jit/jit.h"
@@ -118,6 +119,9 @@ static void show_instrumentation_count(const char *qlabel, int which,
 									   PlanState *planstate, ExplainState *es);
 static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
 static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
+static void show_join_pruning_result_info(Bitmapset *join_prune_paramids,
+										  ExplainState *es);
+static void show_joinpartprune_info(HashState *hashstate, ExplainState *es);
 static const char *explain_get_index_name(Oid indexId);
 static void show_buffer_usage(ExplainState *es, const BufferUsage *usage,
 							  bool planning);
@@ -2057,9 +2061,17 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			show_incremental_sort_info(castNode(IncrementalSortState, planstate),
 									   es);
 			break;
+		case T_Append:
+			if (es->verbose)
+				show_join_pruning_result_info(((Append *) plan)->join_prune_paramids,
+											  es);
+			break;
 		case T_MergeAppend:
 			show_merge_append_keys(castNode(MergeAppendState, planstate),
 								   ancestors, es);
+			if (es->verbose)
+				show_join_pruning_result_info(((MergeAppend *) plan)->join_prune_paramids,
+											  es);
 			break;
 		case T_Result:
 			show_upper_qual((List *) ((Result *) plan)->resconstantqual,
@@ -2075,6 +2087,8 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			break;
 		case T_Hash:
 			show_hash_info(castNode(HashState, planstate), es);
+			if (es->verbose)
+				show_joinpartprune_info(castNode(HashState, planstate), es);
 			break;
 		case T_Memoize:
 			show_memoize_info(castNode(MemoizeState, planstate), ancestors,
@@ -3515,6 +3529,53 @@ show_eval_params(Bitmapset *bms_params, ExplainState *es)
 		ExplainPropertyList("Params Evaluated", params, es);
 }
 
+/*
+ * Show join partition pruning results at Append/MergeAppend nodes.
+ */
+static void
+show_join_pruning_result_info(Bitmapset *join_prune_paramids, ExplainState *es)
+{
+	int			paramid = -1;
+	List	   *params = NIL;
+
+	if (bms_is_empty(join_prune_paramids))
+		return;
+
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Join Partition Pruning", params, es);
+}
+
+/*
+ * Show join partition pruning infos at Hash nodes.
+ */
+static void
+show_joinpartprune_info(HashState *hashstate, ExplainState *es)
+{
+	List	   *params = NIL;
+	ListCell   *lc;
+
+	if (!hashstate->joinpartprune_state_list)
+		return;
+
+	foreach(lc, hashstate->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", jpstate->paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Partition Prune", params, es);
+}
+
 /*
  * Fetch the name of an index in an EXPLAIN
  *
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index f6c34328b8..35a9149a39 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -199,6 +199,8 @@ static void find_matching_subplans_recurse(PartitionPruningData *prunedata,
 										   PartitionedRelPruningData *pprune,
 										   bool initial_prune,
 										   Bitmapset **validsubplans);
+static bool get_join_prune_matching_subplans(PlanState *planstate,
+											 Bitmapset **partset);
 
 
 /*
@@ -1806,7 +1808,7 @@ ExecInitPartitionPruning(PlanState *planstate,
 	 * Perform an initial partition prune pass, if required.
 	 */
 	if (prunestate->do_initial_prune)
-		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true);
+		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true, NULL);
 	else
 	{
 		/* No pruning, so we'll need to initialize all subplans */
@@ -1836,6 +1838,37 @@ ExecInitPartitionPruning(PlanState *planstate,
 	return prunestate;
 }
 
+/*
+ * ExecInitJoinpartpruneList
+ *		Initialize data structures needed for join partition pruning
+ */
+List *
+ExecInitJoinpartpruneList(PlanState *planstate,
+						  List *joinpartprune_info_list)
+{
+	ListCell   *lc;
+	List	   *result = NIL;
+
+	foreach(lc, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(lc);
+		JoinPartitionPruneState *jpstate = palloc(sizeof(JoinPartitionPruneState));
+
+		jpstate->part_prune_state =
+			CreatePartitionPruneState(planstate, jpinfo->part_prune_info);
+		Assert(jpstate->part_prune_state->do_exec_prune);
+
+		jpstate->paramid = jpinfo->paramid;
+		jpstate->nplans = jpinfo->nplans;
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+
+		result = lappend(result, jpstate);
+	}
+
+	return result;
+}
+
 /*
  * CreatePartitionPruneState
  *		Build the data structure required for calling ExecFindMatchingSubPlans
@@ -2273,7 +2306,9 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
 /*
  * ExecFindMatchingSubPlans
  *		Determine which subplans match the pruning steps detailed in
- *		'prunestate' for the current comparison expression values.
+ *		'prunestate' if any for the current comparison expression values, and
+ *		meanwhile match the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.
  *
  * Pass initial_prune if PARAM_EXEC Params cannot yet be evaluated.  This
  * differentiates the initial executor-time pruning step from later
@@ -2281,11 +2316,30 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
  */
 Bitmapset *
 ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-						 bool initial_prune)
+						 bool initial_prune,
+						 PlanState *planstate)
 {
 	Bitmapset  *result = NULL;
 	MemoryContext oldcontext;
 	int			i;
+	Bitmapset  *join_prune_partset = NULL;
+	bool		do_join_prune;
+
+	/* Retrieve the join partition pruning results if any */
+	do_join_prune =
+		get_join_prune_matching_subplans(planstate, &join_prune_partset);
+
+	/*
+	 * Either we're here on partition prune done according to the pruning steps
+	 * detailed in 'prunestate', or we have done join partition prune.
+	 */
+	Assert(do_join_prune || prunestate != NULL);
+
+	/*
+	 * If there is no 'prunestate', then rely entirely on join pruning.
+	 */
+	if (prunestate == NULL)
+		return join_prune_partset;
 
 	/*
 	 * Either we're here on the initial prune done during pruning
@@ -2326,6 +2380,10 @@ ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
 	/* Add in any subplans that partition pruning didn't account for */
 	result = bms_add_members(result, prunestate->other_subplans);
 
+	/* Intersect join partition pruning results */
+	if (do_join_prune)
+		result = bms_intersect(result, join_prune_partset);
+
 	MemoryContextSwitchTo(oldcontext);
 
 	/* Copy result out of the temp context before we reset it */
@@ -2396,3 +2454,66 @@ find_matching_subplans_recurse(PartitionPruningData *prunedata,
 		}
 	}
 }
+
+/*
+ * get_join_prune_matching_subplans
+ *		Retrieve the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.  Return true if we can
+ *		do join partition pruning, otherwise return false.
+ *
+ * Adds valid (non-prunable) subplan IDs to *partset
+ */
+static bool
+get_join_prune_matching_subplans(PlanState *planstate, Bitmapset **partset)
+{
+	Bitmapset  *join_prune_paramids;
+	int			nplans;
+	int			paramid;
+
+	if (planstate == NULL)
+		return false;
+
+	if (IsA(planstate, AppendState))
+	{
+		join_prune_paramids =
+			((Append *) planstate->plan)->join_prune_paramids;
+		nplans = ((AppendState *) planstate)->as_nplans;
+	}
+	else if (IsA(planstate, MergeAppendState))
+	{
+		join_prune_paramids =
+			((MergeAppend *) planstate->plan)->join_prune_paramids;
+		nplans = ((MergeAppendState *) planstate)->ms_nplans;
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(planstate));
+		return false;
+	}
+
+	if (bms_is_empty(join_prune_paramids))
+		return false;
+
+	Assert(nplans > 0);
+	*partset = bms_add_range(NULL, 0, nplans - 1);
+
+	paramid = -1;
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		ParamExecData *param;
+		JoinPartitionPruneState *jpstate;
+
+		param = &(planstate->state->es_param_exec_vals[paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		jpstate = (JoinPartitionPruneState *) DatumGetPointer(param->value);
+
+		if (jpstate != NULL)
+			*partset = bms_intersect(*partset, jpstate->part_prune_result);
+		else	/* the Hash node for this pruning has not been executed */
+			elog(WARNING, "Join partition pruning $%d has not been performed yet.",
+				 paramid);
+	}
+
+	return true;
+}
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 609df6b9e6..c8dd8583d2 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -151,11 +151,13 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill as_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill as_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 		{
 			appendstate->as_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 			appendstate->as_valid_subplans_identified = true;
@@ -170,10 +172,18 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		appendstate->as_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
-		appendstate->as_valid_subplans_identified = true;
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		appendstate->as_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill as_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+		{
+			appendstate->as_valid_subplans = validsubplans;
+			appendstate->as_valid_subplans_identified = true;
+		}
 	}
 
 	/*
@@ -580,7 +590,7 @@ choose_next_subplan_locally(AppendState *node)
 		else if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 		}
 
@@ -647,7 +657,7 @@ choose_next_subplan_for_leader(AppendState *node)
 		if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 
 			/*
@@ -723,7 +733,7 @@ choose_next_subplan_for_worker(AppendState *node)
 	else if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		mark_invalid_subplans_as_finished(node);
@@ -876,7 +886,7 @@ ExecAppendAsyncBegin(AppendState *node)
 	if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		classify_matching_subplans(node);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index e72f0986c2..9ca8bf49d9 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -31,6 +31,7 @@
 #include "catalog/pg_statistic.h"
 #include "commands/tablespace.h"
 #include "executor/execdebug.h"
+#include "executor/execPartition.h"
 #include "executor/hashjoin.h"
 #include "executor/nodeHash.h"
 #include "executor/nodeHashjoin.h"
@@ -48,6 +49,8 @@ static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable);
+static void ExecJoinPartitionPrune(HashState *node);
+static void ExecStoreJoinPartitionPruneResult(HashState *node);
 static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node,
 								  int mcvsToUse);
 static void ExecHashSkewTableInsert(HashJoinTable hashtable,
@@ -189,8 +192,14 @@ MultiExecPrivateHash(HashState *node)
 			}
 			hashtable->totalTuples += 1;
 		}
+
+		/* Perform join partition pruning */
+		ExecJoinPartitionPrune(node);
 	}
 
+	/* Store the surviving partitions for Append/MergeAppend nodes */
+	ExecStoreJoinPartitionPruneResult(node);
+
 	/* resize the hash table if needed (NTUP_PER_BUCKET exceeded) */
 	if (hashtable->nbuckets != hashtable->nbuckets_optimal)
 		ExecHashIncreaseNumBuckets(hashtable);
@@ -401,6 +410,12 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	hashstate->hashkeys =
 		ExecInitExprList(node->hashkeys, (PlanState *) hashstate);
 
+	/*
+	 * initialize join partition pruning infos
+	 */
+	hashstate->joinpartprune_state_list =
+		ExecInitJoinpartpruneList(&hashstate->ps, node->joinpartprune_info_list);
+
 	return hashstate;
 }
 
@@ -1601,6 +1616,56 @@ ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable)
 	}
 }
 
+/*
+ * ExecJoinPartitionPrune
+ *		Perform join partition pruning at this join for each
+ *		JoinPartitionPruneState.
+ */
+static void
+ExecJoinPartitionPrune(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		Bitmapset	   *matching_subPlans;
+
+		if (jpstate->finished)
+			continue;
+
+		matching_subPlans =
+			ExecFindMatchingSubPlans(jpstate->part_prune_state, false, NULL);
+		jpstate->part_prune_result =
+			bms_add_members(jpstate->part_prune_result, matching_subPlans);
+
+		if (bms_num_members(jpstate->part_prune_result) == jpstate->nplans)
+			jpstate->finished = true;
+	}
+}
+
+/*
+ * ExecStoreJoinPartitionPruneResult
+ *		For each JoinPartitionPruneState, store the set of surviving partitions
+ *		to make it available for the Append/MergeAppend node.
+ */
+static void
+ExecStoreJoinPartitionPruneResult(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		ParamExecData	   *param;
+
+		param = &(node->ps.state->es_param_exec_vals[jpstate->paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		param->value = PointerGetDatum(jpstate);
+	}
+}
+
 /*
  * ExecHashTableInsert
  *		insert a tuple into the hash table depending on the hash value
@@ -2345,6 +2410,16 @@ void
 ExecReScanHash(HashState *node)
 {
 	PlanState  *outerPlan = outerPlanState(node);
+	ListCell   *lc;
+
+	/* reset the state in JoinPartitionPruneStates */
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+	}
 
 	/*
 	 * if chgParam of subnode is not null then plan will be re-scanned by
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 25a2d78f15..ddca824206 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -311,6 +311,16 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 					 */
 					node->hj_FirstOuterTupleSlot = NULL;
 				}
+				else if (hashNode->joinpartprune_state_list != NIL)
+				{
+					/*
+					 * Give the hash node a chance to run join partition
+					 * pruning if there is any JoinPartitionPruneState that can
+					 * be evaluated at it.  So do not apply the empty-outer
+					 * optimization in this case.
+					 */
+					node->hj_FirstOuterTupleSlot = NULL;
+				}
 				else if (HJ_FILL_OUTER(node) ||
 						 (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
 						  !node->hj_OuterNotEmpty))
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 21b5726e6e..9eb276abc8 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -99,11 +99,13 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill ms_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill ms_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 			mergestate->ms_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 	}
 	else
@@ -115,9 +117,15 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		mergestate->ms_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		mergestate->ms_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill ms_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+			mergestate->ms_valid_subplans = validsubplans;
 	}
 
 	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
@@ -218,7 +226,7 @@ ExecMergeAppend(PlanState *pstate)
 		 */
 		if (node->ms_valid_subplans == NULL)
 			node->ms_valid_subplans =
-				ExecFindMatchingSubPlans(node->ms_prune_state, false);
+				ExecFindMatchingSubPlans(node->ms_prune_state, false, &node->ps);
 
 		/*
 		 * First time through: pull the first tuple from each valid subplan,
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index d6ceafd51c..9bdc88a9db 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -173,6 +173,10 @@ static void get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
 static bool has_indexed_join_quals(NestPath *path);
 static double approx_tuple_count(PlannerInfo *root, JoinPath *path,
 								 List *quals);
+static double get_joinrel_matching_outer_size(PlannerInfo *root,
+											  RelOptInfo *outer_rel,
+											  Relids inner_relids,
+											  List *restrictlist);
 static double calc_joinrel_size_estimate(PlannerInfo *root,
 										 RelOptInfo *joinrel,
 										 RelOptInfo *outer_rel,
@@ -5380,6 +5384,61 @@ get_parameterized_joinrel_size(PlannerInfo *root, RelOptInfo *rel,
 	return nrows;
 }
 
+/*
+ * get_joinrel_matching_outer_size
+ *		Make a size estimate for the outer side that matches the inner side.
+ */
+static double
+get_joinrel_matching_outer_size(PlannerInfo *root,
+								RelOptInfo *outer_rel,
+								Relids inner_relids,
+								List *restrictlist)
+{
+	double		nrows;
+	Selectivity fkselec;
+	Selectivity jselec;
+	SpecialJoinInfo *sjinfo;
+	SpecialJoinInfo sjinfo_data;
+
+	sjinfo = &sjinfo_data;
+	sjinfo->type = T_SpecialJoinInfo;
+	sjinfo->min_lefthand = outer_rel->relids;
+	sjinfo->min_righthand = inner_relids;
+	sjinfo->syn_lefthand = outer_rel->relids;
+	sjinfo->syn_righthand = inner_relids;
+	sjinfo->jointype = JOIN_SEMI;
+	sjinfo->ojrelid = 0;
+	sjinfo->commute_above_l = NULL;
+	sjinfo->commute_above_r = NULL;
+	sjinfo->commute_below_l = NULL;
+	sjinfo->commute_below_r = NULL;
+	/* we don't bother trying to make the remaining fields valid */
+	sjinfo->lhs_strict = false;
+	sjinfo->semi_can_btree = false;
+	sjinfo->semi_can_hash = false;
+	sjinfo->semi_operators = NIL;
+	sjinfo->semi_rhs_exprs = NIL;
+
+	fkselec = get_foreign_key_join_selectivity(root,
+											   outer_rel->relids,
+											   inner_relids,
+											   sjinfo,
+											   &restrictlist);
+	jselec = clauselist_selectivity(root,
+									restrictlist,
+									0,
+									sjinfo->jointype,
+									sjinfo);
+
+	nrows = outer_rel->rows * fkselec * jselec;
+	nrows = clamp_row_est(nrows);
+
+	/* For safety, make sure result is not more than the base estimate */
+	if (nrows > outer_rel->rows)
+		nrows = outer_rel->rows;
+	return nrows;
+}
+
 /*
  * calc_joinrel_size_estimate
  *		Workhorse for set_joinrel_size_estimates and
@@ -6495,3 +6554,50 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel, Path *bitmapqual,
 
 	return pages_fetched;
 }
+
+/*
+ * compute_partprune_cost
+ *		Compute the overhead of join partition pruning.
+ */
+double
+compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+					   Cost append_total_cost, int append_nplans,
+					   Relids inner_relids, double inner_rows,
+					   List *prunequal)
+{
+	Cost		prune_cost;
+	Cost		saved_cost;
+	double		matching_outer_rows;
+	double		unmatched_nplans;
+
+	switch (appendrel->part_scheme->strategy)
+	{
+
+		case PARTITION_STRATEGY_LIST:
+		case PARTITION_STRATEGY_RANGE:
+			prune_cost = cpu_operator_cost * LOG2(append_nplans) * inner_rows;
+			break;
+		case PARTITION_STRATEGY_HASH:
+			prune_cost = cpu_operator_cost * append_nplans * inner_rows;
+			break;
+		default:
+			elog(ERROR, "unexpected partition strategy: %d",
+				 (int) appendrel->part_scheme->strategy);
+			break;
+	}
+
+	matching_outer_rows =
+		get_joinrel_matching_outer_size(root,
+										appendrel,
+										inner_relids,
+										prunequal);
+
+	/*
+	 * We assume that each outer joined row occupies one new partition.  This
+	 * is really the worst case.
+	 */
+	unmatched_nplans = append_nplans - Min(matching_outer_rows, append_nplans);
+	saved_cost = (unmatched_nplans / append_nplans) * append_total_cost;
+
+	return prune_cost - saved_cost;
+}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 34ca6d4ac2..308ff452d3 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -242,7 +242,8 @@ static Hash *make_hash(Plan *lefttree,
 					   List *hashkeys,
 					   Oid skewTable,
 					   AttrNumber skewColumn,
-					   bool skewInherit);
+					   bool skewInherit,
+					   List *joinpartprune_info_list);
 static MergeJoin *make_mergejoin(List *tlist,
 								 List *joinclauses, List *otherclauses,
 								 List *mergeclauses,
@@ -342,6 +343,7 @@ create_plan(PlannerInfo *root, Path *best_path)
 	/* Initialize this module's workspace in PlannerInfo */
 	root->curOuterRels = NULL;
 	root->curOuterParams = NIL;
+	root->join_partition_prune_candidates = NIL;
 
 	/* Recursively process the path tree, demanding the correct tlist result */
 	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
@@ -369,6 +371,8 @@ create_plan(PlannerInfo *root, Path *best_path)
 	if (root->curOuterParams != NIL)
 		elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
 
+	Assert(root->join_partition_prune_candidates == NIL);
+
 	/*
 	 * Reset plan_params to ensure param IDs used for nestloop params are not
 	 * re-used later
@@ -1223,6 +1227,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	int			nasyncplans = 0;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 	int			nodenumsortkeys = 0;
 	AttrNumber *nodeSortColIdx = NULL;
 	Oid		   *nodeSortOperators = NULL;
@@ -1377,6 +1382,8 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1399,13 +1406,20 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 			partpruneinfo =
 				make_partition_pruneinfo(root, rel,
 										 best_path->subpaths,
-										 prunequal);
+										 prunequal,
+										 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	plan->appendplans = subplans;
 	plan->nasyncplans = nasyncplans;
 	plan->first_partial_plan = best_path->first_partial_path;
 	plan->part_prune_info = partpruneinfo;
+	plan->join_prune_paramids = join_prune_paramids;
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -1445,6 +1459,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	ListCell   *subpaths;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 
 	/*
 	 * We don't have the actual creation of the MergeAppend node split out
@@ -1541,6 +1556,8 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1554,11 +1571,18 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		if (prunequal != NIL)
 			partpruneinfo = make_partition_pruneinfo(root, rel,
 													 best_path->subpaths,
-													 prunequal);
+													 prunequal,
+													 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	node->mergeplans = subplans;
 	node->part_prune_info = partpruneinfo;
+	node->join_prune_paramids = join_prune_paramids;
 
 	/*
 	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
@@ -4734,6 +4758,13 @@ create_hashjoin_plan(PlannerInfo *root,
 	AttrNumber	skewColumn = InvalidAttrNumber;
 	bool		skewInherit = false;
 	ListCell   *lc;
+	List	   *joinpartprune_info_list;
+
+	/*
+	 * Collect information required to build JoinPartitionPruneInfos at this
+	 * join.
+	 */
+	prepare_join_partition_prune_candidate(root, &best_path->jpath);
 
 	/*
 	 * HashJoin can project, so we don't have to demand exact tlists from the
@@ -4745,6 +4776,11 @@ create_hashjoin_plan(PlannerInfo *root,
 	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
 									 (best_path->num_batches > 1) ? CP_SMALL_TLIST : 0);
 
+	/*
+	 * Retrieve all the JoinPartitionPruneInfos for this join.
+	 */
+	joinpartprune_info_list = get_join_partition_prune_candidate(root);
+
 	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
 									 CP_SMALL_TLIST);
 
@@ -4850,7 +4886,8 @@ create_hashjoin_plan(PlannerInfo *root,
 						  inner_hashkeys,
 						  skewTable,
 						  skewColumn,
-						  skewInherit);
+						  skewInherit,
+						  joinpartprune_info_list);
 
 	/*
 	 * Set Hash node's startup & total costs equal to total cost of input
@@ -5977,7 +6014,8 @@ make_hash(Plan *lefttree,
 		  List *hashkeys,
 		  Oid skewTable,
 		  AttrNumber skewColumn,
-		  bool skewInherit)
+		  bool skewInherit,
+		  List *joinpartprune_info_list)
 {
 	Hash	   *node = makeNode(Hash);
 	Plan	   *plan = &node->plan;
@@ -5991,6 +6029,7 @@ make_hash(Plan *lefttree,
 	node->skewTable = skewTable;
 	node->skewColumn = skewColumn;
 	node->skewInherit = skewInherit;
+	node->joinpartprune_info_list = joinpartprune_info_list;
 
 	return node;
 }
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index fc3709510d..c416e7ccda 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -156,6 +156,11 @@ static Plan *set_mergeappend_references(PlannerInfo *root,
 										MergeAppend *mplan,
 										int rtoffset);
 static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_joinpartitionprune_references(PlannerInfo *root,
+											  List *joinpartprune_info_list,
+											  indexed_tlist *outer_itlist,
+											  int rtoffset,
+											  double num_exec);
 static Relids offset_relid_set(Relids relids, int rtoffset);
 static Node *fix_scan_expr(PlannerInfo *root, Node *node,
 						   int rtoffset, double num_exec);
@@ -1897,6 +1902,62 @@ set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset)
 
 	/* Hash nodes don't have their own quals */
 	Assert(plan->qual == NIL);
+
+	set_joinpartitionprune_references(root,
+									  hplan->joinpartprune_info_list,
+									  outer_itlist,
+									  rtoffset,
+									  NUM_EXEC_TLIST(plan));
+}
+
+/*
+ * set_joinpartitionprune_references
+ *	   Do set_plan_references processing on JoinPartitionPruneInfos
+ */
+static void
+set_joinpartitionprune_references(PlannerInfo *root,
+								  List *joinpartprune_info_list,
+								  indexed_tlist *outer_itlist,
+								  int rtoffset,
+								  double num_exec)
+{
+	ListCell   *l;
+
+	foreach(l, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(l);
+		ListCell   *l1;
+
+		foreach(l1, jpinfo->part_prune_info->prune_infos)
+		{
+			List	   *prune_infos = lfirst(l1);
+			ListCell   *l2;
+
+			foreach(l2, prune_infos)
+			{
+				PartitionedRelPruneInfo *pinfo = lfirst(l2);
+
+				pinfo->rtindex += rtoffset;
+
+				pinfo->initial_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->initial_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+				pinfo->exec_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->exec_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+			}
+		}
+	}
 }
 
 /*
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 3f31ecc956..0125ab0fed 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -48,7 +48,9 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/cost.h"
 #include "optimizer/optimizer.h"
+#include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/restrictinfo.h"
 #include "parser/parsetree.h"
 #include "partitioning/partbounds.h"
 #include "partitioning/partprune.h"
@@ -103,15 +105,16 @@ typedef enum PartClauseTarget
  *
  * gen_partprune_steps() initializes and returns an instance of this struct.
  *
- * Note that has_mutable_op, has_mutable_arg, and has_exec_param are set if
- * we found any potentially-useful-for-pruning clause having those properties,
- * whether or not we actually used the clause in the steps list.  This
- * definition allows us to skip the PARTTARGET_EXEC pass in some cases.
+ * Note that has_mutable_op, has_mutable_arg, has_exec_param and has_vars are
+ * set if we found any potentially-useful-for-pruning clause having those
+ * properties, whether or not we actually used the clause in the steps list.
+ * This definition allows us to skip the PARTTARGET_EXEC pass in some cases.
  */
 typedef struct GeneratePruningStepsContext
 {
 	/* Copies of input arguments for gen_partprune_steps: */
 	RelOptInfo *rel;			/* the partitioned relation */
+	Bitmapset  *available_rels;	/* rels whose Vars may be used for pruning */
 	PartClauseTarget target;	/* use-case we're generating steps for */
 	/* Result data: */
 	List	   *steps;			/* list of PartitionPruneSteps */
@@ -119,6 +122,7 @@ typedef struct GeneratePruningStepsContext
 	bool		has_mutable_arg;	/* clauses include any mutable comparison
 									 * values, *other than* exec params */
 	bool		has_exec_param; /* clauses include any PARAM_EXEC params */
+	bool		has_vars;		/* clauses include any Vars from 'available_rels' */
 	bool		contradictory;	/* clauses were proven self-contradictory */
 	/* Working state: */
 	int			next_step_id;
@@ -144,8 +148,10 @@ static List *make_partitionedrel_pruneinfo(PlannerInfo *root,
 										   List *prunequal,
 										   Bitmapset *partrelids,
 										   int *relid_subplan_map,
+										   Bitmapset *available_rels,
 										   Bitmapset **matchedsubplans);
 static void gen_partprune_steps(RelOptInfo *rel, List *clauses,
+								Bitmapset *available_rels,
 								PartClauseTarget target,
 								GeneratePruningStepsContext *context);
 static List *gen_partprune_steps_internal(GeneratePruningStepsContext *context,
@@ -204,6 +210,10 @@ static PartClauseMatchStatus match_boolean_partition_clause(Oid partopfamily,
 static void partkey_datum_from_expr(PartitionPruneContext *context,
 									Expr *expr, int stateidx,
 									Datum *value, bool *isnull);
+static bool contain_forbidden_var_clause(Node *node,
+										 GeneratePruningStepsContext *context);
+static bool contain_forbidden_var_clause_walker(Node *node,
+												GeneratePruningStepsContext *context);
 
 
 /*
@@ -216,11 +226,14 @@ static void partkey_datum_from_expr(PartitionPruneContext *context,
  * 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).
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
  */
 PartitionPruneInfo *
 make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 						 List *subpaths,
-						 List *prunequal)
+						 List *prunequal,
+						 Bitmapset *available_rels)
 {
 	PartitionPruneInfo *pruneinfo;
 	Bitmapset  *allmatchedsubplans = NULL;
@@ -313,6 +326,7 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 												  prunequal,
 												  partrelids,
 												  relid_subplan_map,
+												  available_rels,
 												  &matchedsubplans);
 
 		/* When pruning is possible, record the matched subplans */
@@ -360,6 +374,174 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	return pruneinfo;
 }
 
+/*
+ * make_join_partition_pruneinfos
+ *		Builds one JoinPartitionPruneInfo for each join at which join partition
+ *		pruning is possible for this appendrel.
+ *
+ * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
+ * of scan paths for its child rels.
+ */
+Bitmapset *
+make_join_partition_pruneinfos(PlannerInfo *root, RelOptInfo *parentrel,
+							   Path *best_path, List *subpaths)
+{
+	Bitmapset  *result = NULL;
+	ListCell   *lc;
+
+	if (!IS_PARTITIONED_REL(parentrel))
+		return NULL;
+
+	foreach(lc, root->join_partition_prune_candidates)
+	{
+		JoinPartitionPruneCandidateInfo *candidate =
+			(JoinPartitionPruneCandidateInfo *) lfirst(lc);
+		PartitionPruneInfo *part_prune_info;
+		List	   *prunequal;
+		Relids		joinrelids;
+		ListCell   *l;
+		double		prune_cost;
+
+		if (candidate == NULL)
+			continue;
+
+		/*
+		 * Identify all joinclauses that are movable to this appendrel given
+		 * this inner side relids.  Only those clauses can be used for join
+		 * partition pruning.
+		 */
+		joinrelids = bms_union(parentrel->relids, candidate->inner_relids);
+		prunequal = NIL;
+		foreach(l, candidate->joinrestrictinfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+
+			if (join_clause_is_movable_into(rinfo,
+											parentrel->relids,
+											joinrelids))
+				prunequal = lappend(prunequal, rinfo);
+		}
+
+		if (prunequal == NIL)
+			continue;
+
+		/*
+		 * Check the overhead of this pruning
+		 */
+		prune_cost = compute_partprune_cost(root,
+											parentrel,
+											best_path->total_cost,
+											list_length(subpaths),
+											candidate->inner_relids,
+											candidate->inner_rows,
+											prunequal);
+		if (prune_cost > 0)
+			continue;
+
+		part_prune_info = make_partition_pruneinfo(root, parentrel,
+												   subpaths,
+												   prunequal,
+												   candidate->inner_relids);
+
+		if (part_prune_info)
+		{
+			JoinPartitionPruneInfo *jpinfo;
+
+			jpinfo = palloc(sizeof(JoinPartitionPruneInfo));
+
+			jpinfo->part_prune_info = part_prune_info;
+			jpinfo->paramid = assign_special_exec_param(root);
+			jpinfo->nplans = list_length(subpaths);
+
+			candidate->joinpartprune_info_list =
+				lappend(candidate->joinpartprune_info_list, jpinfo);
+
+			result = bms_add_member(result, jpinfo->paramid);
+		}
+	}
+
+	return result;
+}
+
+/*
+ * prepare_join_partition_prune_candidate
+ * 		Check if join partition pruning is possible at this join and if so
+ * 		collect information required to build JoinPartitionPruneInfos.
+ *
+ * Note that we may build more than one JoinPartitionPruneInfo at one join, for
+ * different Append/MergeAppend paths.
+ */
+void
+prepare_join_partition_prune_candidate(PlannerInfo *root, JoinPath *jpath)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+
+	if (!enable_partition_pruning)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * We cannot perform join partition pruning if the outer is the
+	 * non-nullable side.
+	 */
+	if (!(jpath->jointype == JOIN_INNER ||
+		  jpath->jointype == JOIN_SEMI ||
+		  jpath->jointype == JOIN_RIGHT ||
+		  jpath->jointype == JOIN_RIGHT_ANTI))
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now we only support HashJoin.
+	 */
+	if (jpath->path.pathtype != T_HashJoin)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	candidate = palloc(sizeof(JoinPartitionPruneCandidateInfo));
+	candidate->joinrestrictinfo = jpath->joinrestrictinfo;
+	candidate->inner_relids = jpath->innerjoinpath->parent->relids;
+	candidate->inner_rows = jpath->innerjoinpath->parent->rows;
+	candidate->joinpartprune_info_list = NIL;
+
+	root->join_partition_prune_candidates =
+		lappend(root->join_partition_prune_candidates, candidate);
+}
+
+/*
+ * get_join_partition_prune_candidate
+ *		Pop out the JoinPartitionPruneCandidateInfo for this join and retrieve
+ *		the JoinPartitionPruneInfos.
+ */
+List *
+get_join_partition_prune_candidate(PlannerInfo *root)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+	List   *result;
+
+	candidate = llast(root->join_partition_prune_candidates);
+	root->join_partition_prune_candidates =
+		list_delete_last(root->join_partition_prune_candidates);
+
+	if (candidate == NULL)
+		return NIL;
+
+	result = candidate->joinpartprune_info_list;
+
+	pfree(candidate);
+
+	return result;
+}
+
 /*
  * add_part_relids
  *		Add new info to a list of Bitmapsets of partitioned relids.
@@ -428,6 +610,8 @@ add_part_relids(List *allpartrelids, Bitmapset *partrelids)
  * partrelids: Set of RT indexes identifying relevant partitioned tables
  *   within a single partitioning hierarchy
  * relid_subplan_map[]: maps child relation relids to subplan indexes
+ * available_rels: the relid set of rels whose Vars may be used for
+ *   pruning.
  * matchedsubplans: on success, receives the set of subplan indexes which
  *   were matched to this partition hierarchy
  *
@@ -440,6 +624,7 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 							  List *prunequal,
 							  Bitmapset *partrelids,
 							  int *relid_subplan_map,
+							  Bitmapset *available_rels,
 							  Bitmapset **matchedsubplans)
 {
 	RelOptInfo *targetpart = NULL;
@@ -539,8 +724,8 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 		 * pruning steps and detects whether there's any possibly-useful quals
 		 * that would require per-scan pruning.
 		 */
-		gen_partprune_steps(subpart, partprunequal, PARTTARGET_INITIAL,
-							&context);
+		gen_partprune_steps(subpart, partprunequal, available_rels,
+							PARTTARGET_INITIAL, &context);
 
 		if (context.contradictory)
 		{
@@ -567,14 +752,15 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			initial_pruning_steps = NIL;
 
 		/*
-		 * If no exec Params appear in potentially-usable pruning clauses,
-		 * then there's no point in even thinking about per-scan pruning.
+		 * If no exec Params or available Vars appear in potentially-usable
+		 * pruning clauses, then there's no point in even thinking about
+		 * per-scan pruning.
 		 */
-		if (context.has_exec_param)
+		if (context.has_exec_param || context.has_vars)
 		{
 			/* ... OK, we'd better think about it */
-			gen_partprune_steps(subpart, partprunequal, PARTTARGET_EXEC,
-								&context);
+			gen_partprune_steps(subpart, partprunequal, available_rels,
+								PARTTARGET_EXEC, &context);
 
 			if (context.contradictory)
 			{
@@ -587,11 +773,14 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			/*
 			 * Detect which exec Params actually got used; the fact that some
 			 * were in available clauses doesn't mean we actually used them.
-			 * Skip per-scan pruning if there are none.
 			 */
 			execparamids = get_partkey_exec_paramids(exec_pruning_steps);
 
-			if (bms_is_empty(execparamids))
+			/*
+			 * Skip per-scan pruning if there are none used exec Params and
+			 * there are none available Vars.
+			 */
+			if (bms_is_empty(execparamids) && !context.has_vars)
 				exec_pruning_steps = NIL;
 		}
 		else
@@ -703,6 +892,9 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  *		Process 'clauses' (typically a rel's baserestrictinfo list of clauses)
  *		and create a list of "partition pruning steps".
  *
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
+ *
  * 'target' tells whether to generate pruning steps for planning (use
  * immutable clauses only), or for executor startup (use any allowable
  * clause except ones containing PARAM_EXEC Params), or for executor
@@ -712,12 +904,13 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  * some subsidiary flags; see the GeneratePruningStepsContext typedef.
  */
 static void
-gen_partprune_steps(RelOptInfo *rel, List *clauses, PartClauseTarget target,
-					GeneratePruningStepsContext *context)
+gen_partprune_steps(RelOptInfo *rel, List *clauses, Bitmapset *available_rels,
+					PartClauseTarget target, GeneratePruningStepsContext *context)
 {
 	/* Initialize all output values to zero/false/NULL */
 	memset(context, 0, sizeof(GeneratePruningStepsContext));
 	context->rel = rel;
+	context->available_rels = available_rels;
 	context->target = target;
 
 	/*
@@ -773,7 +966,7 @@ prune_append_rel_partitions(RelOptInfo *rel)
 	 * If the clauses are found to be contradictory, we can return the empty
 	 * set.
 	 */
-	gen_partprune_steps(rel, clauses, PARTTARGET_PLANNER,
+	gen_partprune_steps(rel, clauses, NULL, PARTTARGET_PLANNER,
 						&gcontext);
 	if (gcontext.contradictory)
 		return NULL;
@@ -1957,9 +2150,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) expr))
+			if (contain_forbidden_var_clause((Node *) expr, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -2155,9 +2349,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) rightop))
+			if (contain_forbidden_var_clause((Node *) rightop, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -3727,3 +3922,54 @@ partkey_datum_from_expr(PartitionPruneContext *context,
 		*value = ExecEvalExprSwitchContext(exprstate, ectx, isnull);
 	}
 }
+
+/*
+ * contain_forbidden_var_clause
+ *	  Recursively scan a clause to discover whether it contains any Var nodes
+ *	  (of the current query level) that do not belong to relations in
+ *	  context->available_rels.
+ *
+ *	  Returns true if any such varnode found.
+ *
+ * Does not examine subqueries, therefore must only be used after reduction
+ * of sublinks to subplans!
+ */
+static bool
+contain_forbidden_var_clause(Node *node, GeneratePruningStepsContext *context)
+{
+	return contain_forbidden_var_clause_walker(node, context);
+}
+
+static bool
+contain_forbidden_var_clause_walker(Node *node, GeneratePruningStepsContext *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		*var = (Var *) node;
+
+		if (var->varlevelsup != 0)
+			return false;
+
+		if (!bms_is_member(var->varno, context->available_rels))
+			return true;		/* abort the tree traversal and return true */
+
+		context->has_vars = true;
+
+		if (context->target != PARTTARGET_EXEC)
+			return true;		/* abort the tree traversal and return true */
+
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+		return true;
+	if (IsA(node, PlaceHolderVar))
+	{
+		if (((PlaceHolderVar *) node)->phlevelsup == 0)
+			return true;		/* abort the tree traversal and return true */
+		/* else fall through to check the contained expr */
+	}
+	return expression_tree_walker(node, contain_forbidden_var_clause_walker,
+								  (void *) context);
+}
diff --git a/src/include/executor/execPartition.h b/src/include/executor/execPartition.h
index 15ec869ac8..720bcc1149 100644
--- a/src/include/executor/execPartition.h
+++ b/src/include/executor/execPartition.h
@@ -121,11 +121,26 @@ typedef struct PartitionPruneState
 	PartitionPruningData *partprunedata[FLEXIBLE_ARRAY_MEMBER];
 } PartitionPruneState;
 
+/*
+ * JoinPartitionPruneState - State object required for plan nodes to perform
+ * join partition pruning.
+ */
+typedef struct JoinPartitionPruneState
+{
+	PartitionPruneState *part_prune_state;
+	int			paramid;
+	int			nplans;
+	bool		finished;
+	Bitmapset  *part_prune_result;
+} JoinPartitionPruneState;
+
 extern PartitionPruneState *ExecInitPartitionPruning(PlanState *planstate,
 													 int n_total_subplans,
 													 PartitionPruneInfo *pruneinfo,
 													 Bitmapset **initially_valid_subplans);
+extern List *ExecInitJoinpartpruneList(PlanState *planstate, List *joinpartprune_info_list);
 extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-										   bool initial_prune);
+										   bool initial_prune,
+										   PlanState *planstate);
 
 #endif							/* EXECPARTITION_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 5d7f17dee0..0aeafcabff 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2678,6 +2678,9 @@ typedef struct HashState
 
 	/* Parallel hash state. */
 	struct ParallelHashJoinState *parallel_state;
+
+	/* Infos for join partition pruning. */
+	List *joinpartprune_state_list;
 } HashState;
 
 /* ----------------
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index ed85dc7414..d066b6105c 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,9 @@ struct PlannerInfo
 	/* not-yet-assigned NestLoopParams */
 	List	   *curOuterParams;
 
+	/* a stack of JoinPartitionPruneInfos */
+	List	   *join_partition_prune_candidates;
+
 	/*
 	 * These fields are workspace for setrefs.c.  Each is an array
 	 * corresponding to glob->subplans.  (We could probably teach
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 24d46c76dc..2453ca39d9 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -276,6 +276,9 @@ typedef struct Append
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } Append;
 
 /* ----------------
@@ -311,6 +314,9 @@ typedef struct MergeAppend
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } MergeAppend;
 
 /* ----------------
@@ -1207,6 +1213,7 @@ typedef struct Hash
 	bool		skewInherit;	/* is outer join rel an inheritance tree? */
 	/* all other info is in the parent HashJoin node */
 	Cardinality rows_total;		/* estimate total rows if parallel_aware */
+	List	   *joinpartprune_info_list;	/* infos for join partition pruning */
 } Hash;
 
 /* ----------------
@@ -1553,6 +1560,29 @@ typedef struct PartitionPruneStepCombine
 	List	   *source_stepids;
 } PartitionPruneStepCombine;
 
+/*
+ * JoinPartitionPruneCandidateInfo - Information required to build
+ * JoinPartitionPruneInfos.
+ */
+typedef struct JoinPartitionPruneCandidateInfo
+{
+	List	   *joinrestrictinfo;
+	Bitmapset  *inner_relids;
+	double		inner_rows;
+	List	   *joinpartprune_info_list;
+} JoinPartitionPruneCandidateInfo;
+
+/*
+ * JoinPartitionPruneInfo - Details required to allow the executor to prune
+ * partitions during join.
+ */
+typedef struct JoinPartitionPruneInfo
+{
+	PartitionPruneInfo *part_prune_info;
+	int			paramid;
+	int			nplans;
+} JoinPartitionPruneInfo;
+
 
 /*
  * Plan invalidation info
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 6d50afbf74..52de844f6d 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -211,5 +211,9 @@ extern void set_foreign_size_estimates(PlannerInfo *root, RelOptInfo *rel);
 extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *target);
 extern double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 								   Path *bitmapqual, int loop_count, Cost *cost, double *tuple);
+extern double compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+									 Cost append_total_cost, int append_nplans,
+									 Relids inner_relids, double inner_rows,
+									 List *prunequal);
 
 #endif							/* COST_H */
diff --git a/src/include/partitioning/partprune.h b/src/include/partitioning/partprune.h
index 8636e04e37..899aa61b34 100644
--- a/src/include/partitioning/partprune.h
+++ b/src/include/partitioning/partprune.h
@@ -19,6 +19,8 @@
 
 struct PlannerInfo;				/* avoid including pathnodes.h here */
 struct RelOptInfo;
+struct Path;
+struct JoinPath;
 
 
 /*
@@ -73,7 +75,15 @@ typedef struct PartitionPruneContext
 extern PartitionPruneInfo *make_partition_pruneinfo(struct PlannerInfo *root,
 													struct RelOptInfo *parentrel,
 													List *subpaths,
-													List *prunequal);
+													List *prunequal,
+													Bitmapset *available_rels);
+extern Bitmapset *make_join_partition_pruneinfos(struct PlannerInfo *root,
+												 struct RelOptInfo *parentrel,
+												 struct Path *best_path,
+												 List *subpaths);
+extern void prepare_join_partition_prune_candidate(struct PlannerInfo *root,
+												   struct JoinPath *jpath);
+extern List *get_join_partition_prune_candidate(struct PlannerInfo *root);
 extern Bitmapset *prune_append_rel_partitions(struct RelOptInfo *rel);
 extern Bitmapset *get_matching_partitions(PartitionPruneContext *context,
 										  List *pruning_steps);
diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 9a4c48c055..a08e7a1f0a 100644
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3003,6 +3003,92 @@ order by tbl1.col1, tprt.col1;
 ------+------
 (0 rows)
 
+-- join partition pruning
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+                         explain_join_partition_pruning                         
+--------------------------------------------------------------------------------
+ Hash Right Join (actual rows=2 loops=1)
+   Output: p1.col1, p2.col1, t.col1
+   Hash Cond: ((p1.col1 = t.col1) AND (p2.col1 = t.col1))
+   ->  Hash Join (actual rows=3 loops=1)
+         Output: p1.col1, p2.col1
+         Hash Cond: (p1.col1 = p2.col1)
+         ->  Append (actual rows=3 loops=1)
+               Join Partition Pruning: $0
+               ->  Seq Scan on public.tprt_1 p1_1 (never executed)
+                     Output: p1_1.col1
+               ->  Seq Scan on public.tprt_2 p1_2 (actual rows=3 loops=1)
+                     Output: p1_2.col1
+               ->  Seq Scan on public.tprt_3 p1_3 (never executed)
+                     Output: p1_3.col1
+               ->  Seq Scan on public.tprt_4 p1_4 (never executed)
+                     Output: p1_4.col1
+               ->  Seq Scan on public.tprt_5 p1_5 (never executed)
+                     Output: p1_5.col1
+               ->  Seq Scan on public.tprt_6 p1_6 (never executed)
+                     Output: p1_6.col1
+         ->  Hash (actual rows=3 loops=1)
+               Output: p2.col1
+               Buckets: 1024  Batches: 1  Memory Usage: NkB
+               ->  Append (actual rows=3 loops=1)
+                     Join Partition Pruning: $1
+                     ->  Seq Scan on public.tprt_1 p2_1 (never executed)
+                           Output: p2_1.col1
+                     ->  Seq Scan on public.tprt_2 p2_2 (actual rows=3 loops=1)
+                           Output: p2_2.col1
+                     ->  Seq Scan on public.tprt_3 p2_3 (never executed)
+                           Output: p2_3.col1
+                     ->  Seq Scan on public.tprt_4 p2_4 (never executed)
+                           Output: p2_4.col1
+                     ->  Seq Scan on public.tprt_5 p2_5 (never executed)
+                           Output: p2_5.col1
+                     ->  Seq Scan on public.tprt_6 p2_6 (never executed)
+                           Output: p2_6.col1
+   ->  Hash (actual rows=2 loops=1)
+         Output: t.col1
+         Buckets: 1024  Batches: 1  Memory Usage: NkB
+         Partition Prune: $0, $1
+         ->  Seq Scan on public.tbl1 t (actual rows=2 loops=1)
+               Output: t.col1
+(43 rows)
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+ col1 | col1 | col1 
+------+------+------
+  501 |  501 |  501
+  505 |  505 |  505
+(2 rows)
+
 drop table tbl1, tprt;
 -- Test with columns defined in varying orders between each level
 create table part_abc (a int not null, b int not null, c int not null) partition by list (a);
diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index 7bf3920827..fc5982edcf 100644
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -727,6 +727,45 @@ select tbl1.col1, tprt.col1 from tbl1
 inner join tprt on tbl1.col1 = tprt.col1
 order by tbl1.col1, tprt.col1;
 
+-- join partition pruning
+
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+
 drop table tbl1, tprt;
 
 -- Test with columns defined in varying orders between each level
-- 
2.31.0

From 9878f4d4ff6f3c4c9b4e5e17b2a2370d40ce047b Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Mon, 14 Aug 2023 14:55:26 +0800
Subject: [PATCH v4] Support run-time partition pruning for hash join

If we have a hash join with an Append node on the outer side, something
like

 Hash Join
   Hash Cond: (pt.a = t.a)
   ->  Append
         ->  Seq Scan on pt_p1 pt_1
         ->  Seq Scan on pt_p2 pt_2
         ->  Seq Scan on pt_p3 pt_3
   ->  Hash
         ->  Seq Scan on t

We can actually prune those subnodes of the Append that cannot possibly
contain any matching tuples from the other side of the join.  To do
that, when building the Hash table, for each row from the inner side we
can compute the minimum set of subnodes that can possibly match the join
condition.  When we have built the Hash table and start to execute the
Append node, we should have known which subnodes are survived and thus
can skip other subnodes.

This patch implements this idea.
---
 src/backend/commands/explain.c                |  61 ++++
 src/backend/executor/execPartition.c          | 127 +++++++-
 src/backend/executor/nodeAppend.c             |  32 +-
 src/backend/executor/nodeHash.c               |  75 +++++
 src/backend/executor/nodeHashjoin.c           |  10 +
 src/backend/executor/nodeMergeAppend.c        |  22 +-
 src/backend/optimizer/path/costsize.c         | 106 +++++++
 src/backend/optimizer/plan/createplan.c       |  49 ++-
 src/backend/optimizer/plan/setrefs.c          |  61 ++++
 src/backend/partitioning/partprune.c          | 288 ++++++++++++++++--
 src/include/executor/execPartition.h          |  17 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/pathnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |  36 +++
 src/include/optimizer/cost.h                  |   4 +
 src/include/partitioning/partprune.h          |  12 +-
 src/test/regress/expected/partition_prune.out |  86 ++++++
 src/test/regress/sql/partition_prune.sql      |  39 +++
 18 files changed, 982 insertions(+), 49 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index f1d71bc54e..c51cf6beb6 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -18,6 +18,7 @@
 #include "commands/createas.h"
 #include "commands/defrem.h"
 #include "commands/prepare.h"
+#include "executor/execPartition.h"
 #include "executor/nodeHash.h"
 #include "foreign/fdwapi.h"
 #include "jit/jit.h"
@@ -118,6 +119,9 @@ static void show_instrumentation_count(const char *qlabel, int which,
 									   PlanState *planstate, ExplainState *es);
 static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
 static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
+static void show_join_pruning_result_info(Bitmapset *join_prune_paramids,
+										  ExplainState *es);
+static void show_joinpartprune_info(HashState *hashstate, ExplainState *es);
 static const char *explain_get_index_name(Oid indexId);
 static void show_buffer_usage(ExplainState *es, const BufferUsage *usage,
 							  bool planning);
@@ -2057,9 +2061,17 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			show_incremental_sort_info(castNode(IncrementalSortState, planstate),
 									   es);
 			break;
+		case T_Append:
+			if (es->verbose)
+				show_join_pruning_result_info(((Append *) plan)->join_prune_paramids,
+											  es);
+			break;
 		case T_MergeAppend:
 			show_merge_append_keys(castNode(MergeAppendState, planstate),
 								   ancestors, es);
+			if (es->verbose)
+				show_join_pruning_result_info(((MergeAppend *) plan)->join_prune_paramids,
+											  es);
 			break;
 		case T_Result:
 			show_upper_qual((List *) ((Result *) plan)->resconstantqual,
@@ -2075,6 +2087,8 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			break;
 		case T_Hash:
 			show_hash_info(castNode(HashState, planstate), es);
+			if (es->verbose)
+				show_joinpartprune_info(castNode(HashState, planstate), es);
 			break;
 		case T_Memoize:
 			show_memoize_info(castNode(MemoizeState, planstate), ancestors,
@@ -3515,6 +3529,53 @@ show_eval_params(Bitmapset *bms_params, ExplainState *es)
 		ExplainPropertyList("Params Evaluated", params, es);
 }
 
+/*
+ * Show join partition pruning results at Append/MergeAppend nodes.
+ */
+static void
+show_join_pruning_result_info(Bitmapset *join_prune_paramids, ExplainState *es)
+{
+	int			paramid = -1;
+	List	   *params = NIL;
+
+	if (bms_is_empty(join_prune_paramids))
+		return;
+
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Join Partition Pruning", params, es);
+}
+
+/*
+ * Show join partition pruning infos at Hash nodes.
+ */
+static void
+show_joinpartprune_info(HashState *hashstate, ExplainState *es)
+{
+	List	   *params = NIL;
+	ListCell   *lc;
+
+	if (!hashstate->joinpartprune_state_list)
+		return;
+
+	foreach(lc, hashstate->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", jpstate->paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Partition Prune", params, es);
+}
+
 /*
  * Fetch the name of an index in an EXPLAIN
  *
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index f6c34328b8..35a9149a39 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -199,6 +199,8 @@ static void find_matching_subplans_recurse(PartitionPruningData *prunedata,
 										   PartitionedRelPruningData *pprune,
 										   bool initial_prune,
 										   Bitmapset **validsubplans);
+static bool get_join_prune_matching_subplans(PlanState *planstate,
+											 Bitmapset **partset);
 
 
 /*
@@ -1806,7 +1808,7 @@ ExecInitPartitionPruning(PlanState *planstate,
 	 * Perform an initial partition prune pass, if required.
 	 */
 	if (prunestate->do_initial_prune)
-		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true);
+		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true, NULL);
 	else
 	{
 		/* No pruning, so we'll need to initialize all subplans */
@@ -1836,6 +1838,37 @@ ExecInitPartitionPruning(PlanState *planstate,
 	return prunestate;
 }
 
+/*
+ * ExecInitJoinpartpruneList
+ *		Initialize data structures needed for join partition pruning
+ */
+List *
+ExecInitJoinpartpruneList(PlanState *planstate,
+						  List *joinpartprune_info_list)
+{
+	ListCell   *lc;
+	List	   *result = NIL;
+
+	foreach(lc, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(lc);
+		JoinPartitionPruneState *jpstate = palloc(sizeof(JoinPartitionPruneState));
+
+		jpstate->part_prune_state =
+			CreatePartitionPruneState(planstate, jpinfo->part_prune_info);
+		Assert(jpstate->part_prune_state->do_exec_prune);
+
+		jpstate->paramid = jpinfo->paramid;
+		jpstate->nplans = jpinfo->nplans;
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+
+		result = lappend(result, jpstate);
+	}
+
+	return result;
+}
+
 /*
  * CreatePartitionPruneState
  *		Build the data structure required for calling ExecFindMatchingSubPlans
@@ -2273,7 +2306,9 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
 /*
  * ExecFindMatchingSubPlans
  *		Determine which subplans match the pruning steps detailed in
- *		'prunestate' for the current comparison expression values.
+ *		'prunestate' if any for the current comparison expression values, and
+ *		meanwhile match the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.
  *
  * Pass initial_prune if PARAM_EXEC Params cannot yet be evaluated.  This
  * differentiates the initial executor-time pruning step from later
@@ -2281,11 +2316,30 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
  */
 Bitmapset *
 ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-						 bool initial_prune)
+						 bool initial_prune,
+						 PlanState *planstate)
 {
 	Bitmapset  *result = NULL;
 	MemoryContext oldcontext;
 	int			i;
+	Bitmapset  *join_prune_partset = NULL;
+	bool		do_join_prune;
+
+	/* Retrieve the join partition pruning results if any */
+	do_join_prune =
+		get_join_prune_matching_subplans(planstate, &join_prune_partset);
+
+	/*
+	 * Either we're here on partition prune done according to the pruning steps
+	 * detailed in 'prunestate', or we have done join partition prune.
+	 */
+	Assert(do_join_prune || prunestate != NULL);
+
+	/*
+	 * If there is no 'prunestate', then rely entirely on join pruning.
+	 */
+	if (prunestate == NULL)
+		return join_prune_partset;
 
 	/*
 	 * Either we're here on the initial prune done during pruning
@@ -2326,6 +2380,10 @@ ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
 	/* Add in any subplans that partition pruning didn't account for */
 	result = bms_add_members(result, prunestate->other_subplans);
 
+	/* Intersect join partition pruning results */
+	if (do_join_prune)
+		result = bms_intersect(result, join_prune_partset);
+
 	MemoryContextSwitchTo(oldcontext);
 
 	/* Copy result out of the temp context before we reset it */
@@ -2396,3 +2454,66 @@ find_matching_subplans_recurse(PartitionPruningData *prunedata,
 		}
 	}
 }
+
+/*
+ * get_join_prune_matching_subplans
+ *		Retrieve the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.  Return true if we can
+ *		do join partition pruning, otherwise return false.
+ *
+ * Adds valid (non-prunable) subplan IDs to *partset
+ */
+static bool
+get_join_prune_matching_subplans(PlanState *planstate, Bitmapset **partset)
+{
+	Bitmapset  *join_prune_paramids;
+	int			nplans;
+	int			paramid;
+
+	if (planstate == NULL)
+		return false;
+
+	if (IsA(planstate, AppendState))
+	{
+		join_prune_paramids =
+			((Append *) planstate->plan)->join_prune_paramids;
+		nplans = ((AppendState *) planstate)->as_nplans;
+	}
+	else if (IsA(planstate, MergeAppendState))
+	{
+		join_prune_paramids =
+			((MergeAppend *) planstate->plan)->join_prune_paramids;
+		nplans = ((MergeAppendState *) planstate)->ms_nplans;
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(planstate));
+		return false;
+	}
+
+	if (bms_is_empty(join_prune_paramids))
+		return false;
+
+	Assert(nplans > 0);
+	*partset = bms_add_range(NULL, 0, nplans - 1);
+
+	paramid = -1;
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		ParamExecData *param;
+		JoinPartitionPruneState *jpstate;
+
+		param = &(planstate->state->es_param_exec_vals[paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		jpstate = (JoinPartitionPruneState *) DatumGetPointer(param->value);
+
+		if (jpstate != NULL)
+			*partset = bms_intersect(*partset, jpstate->part_prune_result);
+		else	/* the Hash node for this pruning has not been executed */
+			elog(WARNING, "Join partition pruning $%d has not been performed yet.",
+				 paramid);
+	}
+
+	return true;
+}
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 609df6b9e6..c8dd8583d2 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -151,11 +151,13 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill as_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill as_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 		{
 			appendstate->as_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 			appendstate->as_valid_subplans_identified = true;
@@ -170,10 +172,18 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		appendstate->as_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
-		appendstate->as_valid_subplans_identified = true;
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		appendstate->as_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill as_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+		{
+			appendstate->as_valid_subplans = validsubplans;
+			appendstate->as_valid_subplans_identified = true;
+		}
 	}
 
 	/*
@@ -580,7 +590,7 @@ choose_next_subplan_locally(AppendState *node)
 		else if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 		}
 
@@ -647,7 +657,7 @@ choose_next_subplan_for_leader(AppendState *node)
 		if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 
 			/*
@@ -723,7 +733,7 @@ choose_next_subplan_for_worker(AppendState *node)
 	else if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		mark_invalid_subplans_as_finished(node);
@@ -876,7 +886,7 @@ ExecAppendAsyncBegin(AppendState *node)
 	if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		classify_matching_subplans(node);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index e72f0986c2..9ca8bf49d9 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -31,6 +31,7 @@
 #include "catalog/pg_statistic.h"
 #include "commands/tablespace.h"
 #include "executor/execdebug.h"
+#include "executor/execPartition.h"
 #include "executor/hashjoin.h"
 #include "executor/nodeHash.h"
 #include "executor/nodeHashjoin.h"
@@ -48,6 +49,8 @@ static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable);
+static void ExecJoinPartitionPrune(HashState *node);
+static void ExecStoreJoinPartitionPruneResult(HashState *node);
 static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node,
 								  int mcvsToUse);
 static void ExecHashSkewTableInsert(HashJoinTable hashtable,
@@ -189,8 +192,14 @@ MultiExecPrivateHash(HashState *node)
 			}
 			hashtable->totalTuples += 1;
 		}
+
+		/* Perform join partition pruning */
+		ExecJoinPartitionPrune(node);
 	}
 
+	/* Store the surviving partitions for Append/MergeAppend nodes */
+	ExecStoreJoinPartitionPruneResult(node);
+
 	/* resize the hash table if needed (NTUP_PER_BUCKET exceeded) */
 	if (hashtable->nbuckets != hashtable->nbuckets_optimal)
 		ExecHashIncreaseNumBuckets(hashtable);
@@ -401,6 +410,12 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	hashstate->hashkeys =
 		ExecInitExprList(node->hashkeys, (PlanState *) hashstate);
 
+	/*
+	 * initialize join partition pruning infos
+	 */
+	hashstate->joinpartprune_state_list =
+		ExecInitJoinpartpruneList(&hashstate->ps, node->joinpartprune_info_list);
+
 	return hashstate;
 }
 
@@ -1601,6 +1616,56 @@ ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable)
 	}
 }
 
+/*
+ * ExecJoinPartitionPrune
+ *		Perform join partition pruning at this join for each
+ *		JoinPartitionPruneState.
+ */
+static void
+ExecJoinPartitionPrune(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		Bitmapset	   *matching_subPlans;
+
+		if (jpstate->finished)
+			continue;
+
+		matching_subPlans =
+			ExecFindMatchingSubPlans(jpstate->part_prune_state, false, NULL);
+		jpstate->part_prune_result =
+			bms_add_members(jpstate->part_prune_result, matching_subPlans);
+
+		if (bms_num_members(jpstate->part_prune_result) == jpstate->nplans)
+			jpstate->finished = true;
+	}
+}
+
+/*
+ * ExecStoreJoinPartitionPruneResult
+ *		For each JoinPartitionPruneState, store the set of surviving partitions
+ *		to make it available for the Append/MergeAppend node.
+ */
+static void
+ExecStoreJoinPartitionPruneResult(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		ParamExecData	   *param;
+
+		param = &(node->ps.state->es_param_exec_vals[jpstate->paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		param->value = PointerGetDatum(jpstate);
+	}
+}
+
 /*
  * ExecHashTableInsert
  *		insert a tuple into the hash table depending on the hash value
@@ -2345,6 +2410,16 @@ void
 ExecReScanHash(HashState *node)
 {
 	PlanState  *outerPlan = outerPlanState(node);
+	ListCell   *lc;
+
+	/* reset the state in JoinPartitionPruneStates */
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+	}
 
 	/*
 	 * if chgParam of subnode is not null then plan will be re-scanned by
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 25a2d78f15..ddca824206 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -311,6 +311,16 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 					 */
 					node->hj_FirstOuterTupleSlot = NULL;
 				}
+				else if (hashNode->joinpartprune_state_list != NIL)
+				{
+					/*
+					 * Give the hash node a chance to run join partition
+					 * pruning if there is any JoinPartitionPruneState that can
+					 * be evaluated at it.  So do not apply the empty-outer
+					 * optimization in this case.
+					 */
+					node->hj_FirstOuterTupleSlot = NULL;
+				}
 				else if (HJ_FILL_OUTER(node) ||
 						 (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
 						  !node->hj_OuterNotEmpty))
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 21b5726e6e..9eb276abc8 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -99,11 +99,13 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill ms_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill ms_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 			mergestate->ms_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 	}
 	else
@@ -115,9 +117,15 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		mergestate->ms_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		mergestate->ms_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill ms_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+			mergestate->ms_valid_subplans = validsubplans;
 	}
 
 	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
@@ -218,7 +226,7 @@ ExecMergeAppend(PlanState *pstate)
 		 */
 		if (node->ms_valid_subplans == NULL)
 			node->ms_valid_subplans =
-				ExecFindMatchingSubPlans(node->ms_prune_state, false);
+				ExecFindMatchingSubPlans(node->ms_prune_state, false, &node->ps);
 
 		/*
 		 * First time through: pull the first tuple from each valid subplan,
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index d6ceafd51c..9bdc88a9db 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -173,6 +173,10 @@ static void get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
 static bool has_indexed_join_quals(NestPath *path);
 static double approx_tuple_count(PlannerInfo *root, JoinPath *path,
 								 List *quals);
+static double get_joinrel_matching_outer_size(PlannerInfo *root,
+											  RelOptInfo *outer_rel,
+											  Relids inner_relids,
+											  List *restrictlist);
 static double calc_joinrel_size_estimate(PlannerInfo *root,
 										 RelOptInfo *joinrel,
 										 RelOptInfo *outer_rel,
@@ -5380,6 +5384,61 @@ get_parameterized_joinrel_size(PlannerInfo *root, RelOptInfo *rel,
 	return nrows;
 }
 
+/*
+ * get_joinrel_matching_outer_size
+ *		Make a size estimate for the outer side that matches the inner side.
+ */
+static double
+get_joinrel_matching_outer_size(PlannerInfo *root,
+								RelOptInfo *outer_rel,
+								Relids inner_relids,
+								List *restrictlist)
+{
+	double		nrows;
+	Selectivity fkselec;
+	Selectivity jselec;
+	SpecialJoinInfo *sjinfo;
+	SpecialJoinInfo sjinfo_data;
+
+	sjinfo = &sjinfo_data;
+	sjinfo->type = T_SpecialJoinInfo;
+	sjinfo->min_lefthand = outer_rel->relids;
+	sjinfo->min_righthand = inner_relids;
+	sjinfo->syn_lefthand = outer_rel->relids;
+	sjinfo->syn_righthand = inner_relids;
+	sjinfo->jointype = JOIN_SEMI;
+	sjinfo->ojrelid = 0;
+	sjinfo->commute_above_l = NULL;
+	sjinfo->commute_above_r = NULL;
+	sjinfo->commute_below_l = NULL;
+	sjinfo->commute_below_r = NULL;
+	/* we don't bother trying to make the remaining fields valid */
+	sjinfo->lhs_strict = false;
+	sjinfo->semi_can_btree = false;
+	sjinfo->semi_can_hash = false;
+	sjinfo->semi_operators = NIL;
+	sjinfo->semi_rhs_exprs = NIL;
+
+	fkselec = get_foreign_key_join_selectivity(root,
+											   outer_rel->relids,
+											   inner_relids,
+											   sjinfo,
+											   &restrictlist);
+	jselec = clauselist_selectivity(root,
+									restrictlist,
+									0,
+									sjinfo->jointype,
+									sjinfo);
+
+	nrows = outer_rel->rows * fkselec * jselec;
+	nrows = clamp_row_est(nrows);
+
+	/* For safety, make sure result is not more than the base estimate */
+	if (nrows > outer_rel->rows)
+		nrows = outer_rel->rows;
+	return nrows;
+}
+
 /*
  * calc_joinrel_size_estimate
  *		Workhorse for set_joinrel_size_estimates and
@@ -6495,3 +6554,50 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel, Path *bitmapqual,
 
 	return pages_fetched;
 }
+
+/*
+ * compute_partprune_cost
+ *		Compute the overhead of join partition pruning.
+ */
+double
+compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+					   Cost append_total_cost, int append_nplans,
+					   Relids inner_relids, double inner_rows,
+					   List *prunequal)
+{
+	Cost		prune_cost;
+	Cost		saved_cost;
+	double		matching_outer_rows;
+	double		unmatched_nplans;
+
+	switch (appendrel->part_scheme->strategy)
+	{
+
+		case PARTITION_STRATEGY_LIST:
+		case PARTITION_STRATEGY_RANGE:
+			prune_cost = cpu_operator_cost * LOG2(append_nplans) * inner_rows;
+			break;
+		case PARTITION_STRATEGY_HASH:
+			prune_cost = cpu_operator_cost * append_nplans * inner_rows;
+			break;
+		default:
+			elog(ERROR, "unexpected partition strategy: %d",
+				 (int) appendrel->part_scheme->strategy);
+			break;
+	}
+
+	matching_outer_rows =
+		get_joinrel_matching_outer_size(root,
+										appendrel,
+										inner_relids,
+										prunequal);
+
+	/*
+	 * We assume that each outer joined row occupies one new partition.  This
+	 * is really the worst case.
+	 */
+	unmatched_nplans = append_nplans - Min(matching_outer_rows, append_nplans);
+	saved_cost = (unmatched_nplans / append_nplans) * append_total_cost;
+
+	return prune_cost - saved_cost;
+}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 34ca6d4ac2..308ff452d3 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -242,7 +242,8 @@ static Hash *make_hash(Plan *lefttree,
 					   List *hashkeys,
 					   Oid skewTable,
 					   AttrNumber skewColumn,
-					   bool skewInherit);
+					   bool skewInherit,
+					   List *joinpartprune_info_list);
 static MergeJoin *make_mergejoin(List *tlist,
 								 List *joinclauses, List *otherclauses,
 								 List *mergeclauses,
@@ -342,6 +343,7 @@ create_plan(PlannerInfo *root, Path *best_path)
 	/* Initialize this module's workspace in PlannerInfo */
 	root->curOuterRels = NULL;
 	root->curOuterParams = NIL;
+	root->join_partition_prune_candidates = NIL;
 
 	/* Recursively process the path tree, demanding the correct tlist result */
 	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
@@ -369,6 +371,8 @@ create_plan(PlannerInfo *root, Path *best_path)
 	if (root->curOuterParams != NIL)
 		elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
 
+	Assert(root->join_partition_prune_candidates == NIL);
+
 	/*
 	 * Reset plan_params to ensure param IDs used for nestloop params are not
 	 * re-used later
@@ -1223,6 +1227,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	int			nasyncplans = 0;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 	int			nodenumsortkeys = 0;
 	AttrNumber *nodeSortColIdx = NULL;
 	Oid		   *nodeSortOperators = NULL;
@@ -1377,6 +1382,8 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1399,13 +1406,20 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 			partpruneinfo =
 				make_partition_pruneinfo(root, rel,
 										 best_path->subpaths,
-										 prunequal);
+										 prunequal,
+										 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	plan->appendplans = subplans;
 	plan->nasyncplans = nasyncplans;
 	plan->first_partial_plan = best_path->first_partial_path;
 	plan->part_prune_info = partpruneinfo;
+	plan->join_prune_paramids = join_prune_paramids;
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -1445,6 +1459,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	ListCell   *subpaths;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 
 	/*
 	 * We don't have the actual creation of the MergeAppend node split out
@@ -1541,6 +1556,8 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1554,11 +1571,18 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		if (prunequal != NIL)
 			partpruneinfo = make_partition_pruneinfo(root, rel,
 													 best_path->subpaths,
-													 prunequal);
+													 prunequal,
+													 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	node->mergeplans = subplans;
 	node->part_prune_info = partpruneinfo;
+	node->join_prune_paramids = join_prune_paramids;
 
 	/*
 	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
@@ -4734,6 +4758,13 @@ create_hashjoin_plan(PlannerInfo *root,
 	AttrNumber	skewColumn = InvalidAttrNumber;
 	bool		skewInherit = false;
 	ListCell   *lc;
+	List	   *joinpartprune_info_list;
+
+	/*
+	 * Collect information required to build JoinPartitionPruneInfos at this
+	 * join.
+	 */
+	prepare_join_partition_prune_candidate(root, &best_path->jpath);
 
 	/*
 	 * HashJoin can project, so we don't have to demand exact tlists from the
@@ -4745,6 +4776,11 @@ create_hashjoin_plan(PlannerInfo *root,
 	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
 									 (best_path->num_batches > 1) ? CP_SMALL_TLIST : 0);
 
+	/*
+	 * Retrieve all the JoinPartitionPruneInfos for this join.
+	 */
+	joinpartprune_info_list = get_join_partition_prune_candidate(root);
+
 	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
 									 CP_SMALL_TLIST);
 
@@ -4850,7 +4886,8 @@ create_hashjoin_plan(PlannerInfo *root,
 						  inner_hashkeys,
 						  skewTable,
 						  skewColumn,
-						  skewInherit);
+						  skewInherit,
+						  joinpartprune_info_list);
 
 	/*
 	 * Set Hash node's startup & total costs equal to total cost of input
@@ -5977,7 +6014,8 @@ make_hash(Plan *lefttree,
 		  List *hashkeys,
 		  Oid skewTable,
 		  AttrNumber skewColumn,
-		  bool skewInherit)
+		  bool skewInherit,
+		  List *joinpartprune_info_list)
 {
 	Hash	   *node = makeNode(Hash);
 	Plan	   *plan = &node->plan;
@@ -5991,6 +6029,7 @@ make_hash(Plan *lefttree,
 	node->skewTable = skewTable;
 	node->skewColumn = skewColumn;
 	node->skewInherit = skewInherit;
+	node->joinpartprune_info_list = joinpartprune_info_list;
 
 	return node;
 }
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index fc3709510d..c416e7ccda 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -156,6 +156,11 @@ static Plan *set_mergeappend_references(PlannerInfo *root,
 										MergeAppend *mplan,
 										int rtoffset);
 static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_joinpartitionprune_references(PlannerInfo *root,
+											  List *joinpartprune_info_list,
+											  indexed_tlist *outer_itlist,
+											  int rtoffset,
+											  double num_exec);
 static Relids offset_relid_set(Relids relids, int rtoffset);
 static Node *fix_scan_expr(PlannerInfo *root, Node *node,
 						   int rtoffset, double num_exec);
@@ -1897,6 +1902,62 @@ set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset)
 
 	/* Hash nodes don't have their own quals */
 	Assert(plan->qual == NIL);
+
+	set_joinpartitionprune_references(root,
+									  hplan->joinpartprune_info_list,
+									  outer_itlist,
+									  rtoffset,
+									  NUM_EXEC_TLIST(plan));
+}
+
+/*
+ * set_joinpartitionprune_references
+ *	   Do set_plan_references processing on JoinPartitionPruneInfos
+ */
+static void
+set_joinpartitionprune_references(PlannerInfo *root,
+								  List *joinpartprune_info_list,
+								  indexed_tlist *outer_itlist,
+								  int rtoffset,
+								  double num_exec)
+{
+	ListCell   *l;
+
+	foreach(l, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(l);
+		ListCell   *l1;
+
+		foreach(l1, jpinfo->part_prune_info->prune_infos)
+		{
+			List	   *prune_infos = lfirst(l1);
+			ListCell   *l2;
+
+			foreach(l2, prune_infos)
+			{
+				PartitionedRelPruneInfo *pinfo = lfirst(l2);
+
+				pinfo->rtindex += rtoffset;
+
+				pinfo->initial_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->initial_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+				pinfo->exec_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->exec_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+			}
+		}
+	}
 }
 
 /*
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 3f31ecc956..a6d6f0ad88 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -48,7 +48,9 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/cost.h"
 #include "optimizer/optimizer.h"
+#include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/restrictinfo.h"
 #include "parser/parsetree.h"
 #include "partitioning/partbounds.h"
 #include "partitioning/partprune.h"
@@ -103,15 +105,16 @@ typedef enum PartClauseTarget
  *
  * gen_partprune_steps() initializes and returns an instance of this struct.
  *
- * Note that has_mutable_op, has_mutable_arg, and has_exec_param are set if
- * we found any potentially-useful-for-pruning clause having those properties,
- * whether or not we actually used the clause in the steps list.  This
- * definition allows us to skip the PARTTARGET_EXEC pass in some cases.
+ * Note that has_mutable_op, has_mutable_arg, has_exec_param and has_vars are
+ * set if we found any potentially-useful-for-pruning clause having those
+ * properties, whether or not we actually used the clause in the steps list.
+ * This definition allows us to skip the PARTTARGET_EXEC pass in some cases.
  */
 typedef struct GeneratePruningStepsContext
 {
 	/* Copies of input arguments for gen_partprune_steps: */
 	RelOptInfo *rel;			/* the partitioned relation */
+	Bitmapset  *available_rels;	/* rels whose Vars may be used for pruning */
 	PartClauseTarget target;	/* use-case we're generating steps for */
 	/* Result data: */
 	List	   *steps;			/* list of PartitionPruneSteps */
@@ -119,6 +122,7 @@ typedef struct GeneratePruningStepsContext
 	bool		has_mutable_arg;	/* clauses include any mutable comparison
 									 * values, *other than* exec params */
 	bool		has_exec_param; /* clauses include any PARAM_EXEC params */
+	bool		has_vars;		/* clauses include any Vars from 'available_rels' */
 	bool		contradictory;	/* clauses were proven self-contradictory */
 	/* Working state: */
 	int			next_step_id;
@@ -144,8 +148,10 @@ static List *make_partitionedrel_pruneinfo(PlannerInfo *root,
 										   List *prunequal,
 										   Bitmapset *partrelids,
 										   int *relid_subplan_map,
+										   Bitmapset *available_rels,
 										   Bitmapset **matchedsubplans);
 static void gen_partprune_steps(RelOptInfo *rel, List *clauses,
+								Bitmapset *available_rels,
 								PartClauseTarget target,
 								GeneratePruningStepsContext *context);
 static List *gen_partprune_steps_internal(GeneratePruningStepsContext *context,
@@ -204,6 +210,10 @@ static PartClauseMatchStatus match_boolean_partition_clause(Oid partopfamily,
 static void partkey_datum_from_expr(PartitionPruneContext *context,
 									Expr *expr, int stateidx,
 									Datum *value, bool *isnull);
+static bool contain_forbidden_var_clause(Node *node,
+										 GeneratePruningStepsContext *context);
+static bool contain_forbidden_var_clause_walker(Node *node,
+												GeneratePruningStepsContext *context);
 
 
 /*
@@ -216,11 +226,14 @@ static void partkey_datum_from_expr(PartitionPruneContext *context,
  * 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).
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
  */
 PartitionPruneInfo *
 make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 						 List *subpaths,
-						 List *prunequal)
+						 List *prunequal,
+						 Bitmapset *available_rels)
 {
 	PartitionPruneInfo *pruneinfo;
 	Bitmapset  *allmatchedsubplans = NULL;
@@ -313,6 +326,7 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 												  prunequal,
 												  partrelids,
 												  relid_subplan_map,
+												  available_rels,
 												  &matchedsubplans);
 
 		/* When pruning is possible, record the matched subplans */
@@ -360,6 +374,174 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	return pruneinfo;
 }
 
+/*
+ * make_join_partition_pruneinfos
+ *		Builds one JoinPartitionPruneInfo for each join at which join partition
+ *		pruning is possible for this appendrel.
+ *
+ * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
+ * of scan paths for its child rels.
+ */
+Bitmapset *
+make_join_partition_pruneinfos(PlannerInfo *root, RelOptInfo *parentrel,
+							   Path *best_path, List *subpaths)
+{
+	Bitmapset  *result = NULL;
+	ListCell   *lc;
+
+	if (!IS_PARTITIONED_REL(parentrel))
+		return NULL;
+
+	foreach(lc, root->join_partition_prune_candidates)
+	{
+		JoinPartitionPruneCandidateInfo *candidate =
+			(JoinPartitionPruneCandidateInfo *) lfirst(lc);
+		PartitionPruneInfo *part_prune_info;
+		List	   *prunequal;
+		Relids		joinrelids;
+		ListCell   *l;
+		double		prune_cost;
+
+		if (candidate == NULL)
+			continue;
+
+		/*
+		 * Identify all joinclauses that are movable to this appendrel given
+		 * this inner side relids.  Only those clauses can be used for join
+		 * partition pruning.
+		 */
+		joinrelids = bms_union(parentrel->relids, candidate->inner_relids);
+		prunequal = NIL;
+		foreach(l, candidate->joinrestrictinfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+
+			if (join_clause_is_movable_into(rinfo,
+											parentrel->relids,
+											joinrelids))
+				prunequal = lappend(prunequal, rinfo);
+		}
+
+		if (prunequal == NIL)
+			continue;
+
+		/*
+		 * Check the overhead of this pruning
+		 */
+		prune_cost = compute_partprune_cost(root,
+											parentrel,
+											best_path->total_cost,
+											list_length(subpaths),
+											candidate->inner_relids,
+											candidate->inner_rows,
+											prunequal);
+		if (prune_cost > 0)
+			continue;
+
+		part_prune_info = make_partition_pruneinfo(root, parentrel,
+												   subpaths,
+												   prunequal,
+												   candidate->inner_relids);
+
+		if (part_prune_info)
+		{
+			JoinPartitionPruneInfo *jpinfo;
+
+			jpinfo = makeNode(JoinPartitionPruneInfo);
+
+			jpinfo->part_prune_info = part_prune_info;
+			jpinfo->paramid = assign_special_exec_param(root);
+			jpinfo->nplans = list_length(subpaths);
+
+			candidate->joinpartprune_info_list =
+				lappend(candidate->joinpartprune_info_list, jpinfo);
+
+			result = bms_add_member(result, jpinfo->paramid);
+		}
+	}
+
+	return result;
+}
+
+/*
+ * prepare_join_partition_prune_candidate
+ * 		Check if join partition pruning is possible at this join and if so
+ * 		collect information required to build JoinPartitionPruneInfos.
+ *
+ * Note that we may build more than one JoinPartitionPruneInfo at one join, for
+ * different Append/MergeAppend paths.
+ */
+void
+prepare_join_partition_prune_candidate(PlannerInfo *root, JoinPath *jpath)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+
+	if (!enable_partition_pruning)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * We cannot perform join partition pruning if the outer is the
+	 * non-nullable side.
+	 */
+	if (!(jpath->jointype == JOIN_INNER ||
+		  jpath->jointype == JOIN_SEMI ||
+		  jpath->jointype == JOIN_RIGHT ||
+		  jpath->jointype == JOIN_RIGHT_ANTI))
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now we only support HashJoin.
+	 */
+	if (jpath->path.pathtype != T_HashJoin)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	candidate = makeNode(JoinPartitionPruneCandidateInfo);
+	candidate->joinrestrictinfo = jpath->joinrestrictinfo;
+	candidate->inner_relids = jpath->innerjoinpath->parent->relids;
+	candidate->inner_rows = jpath->innerjoinpath->parent->rows;
+	candidate->joinpartprune_info_list = NIL;
+
+	root->join_partition_prune_candidates =
+		lappend(root->join_partition_prune_candidates, candidate);
+}
+
+/*
+ * get_join_partition_prune_candidate
+ *		Pop out the JoinPartitionPruneCandidateInfo for this join and retrieve
+ *		the JoinPartitionPruneInfos.
+ */
+List *
+get_join_partition_prune_candidate(PlannerInfo *root)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+	List   *result;
+
+	candidate = llast(root->join_partition_prune_candidates);
+	root->join_partition_prune_candidates =
+		list_delete_last(root->join_partition_prune_candidates);
+
+	if (candidate == NULL)
+		return NIL;
+
+	result = candidate->joinpartprune_info_list;
+
+	pfree(candidate);
+
+	return result;
+}
+
 /*
  * add_part_relids
  *		Add new info to a list of Bitmapsets of partitioned relids.
@@ -428,6 +610,8 @@ add_part_relids(List *allpartrelids, Bitmapset *partrelids)
  * partrelids: Set of RT indexes identifying relevant partitioned tables
  *   within a single partitioning hierarchy
  * relid_subplan_map[]: maps child relation relids to subplan indexes
+ * available_rels: the relid set of rels whose Vars may be used for
+ *   pruning.
  * matchedsubplans: on success, receives the set of subplan indexes which
  *   were matched to this partition hierarchy
  *
@@ -440,6 +624,7 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 							  List *prunequal,
 							  Bitmapset *partrelids,
 							  int *relid_subplan_map,
+							  Bitmapset *available_rels,
 							  Bitmapset **matchedsubplans)
 {
 	RelOptInfo *targetpart = NULL;
@@ -539,8 +724,8 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 		 * pruning steps and detects whether there's any possibly-useful quals
 		 * that would require per-scan pruning.
 		 */
-		gen_partprune_steps(subpart, partprunequal, PARTTARGET_INITIAL,
-							&context);
+		gen_partprune_steps(subpart, partprunequal, available_rels,
+							PARTTARGET_INITIAL, &context);
 
 		if (context.contradictory)
 		{
@@ -567,14 +752,15 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			initial_pruning_steps = NIL;
 
 		/*
-		 * If no exec Params appear in potentially-usable pruning clauses,
-		 * then there's no point in even thinking about per-scan pruning.
+		 * If no exec Params or available Vars appear in potentially-usable
+		 * pruning clauses, then there's no point in even thinking about
+		 * per-scan pruning.
 		 */
-		if (context.has_exec_param)
+		if (context.has_exec_param || context.has_vars)
 		{
 			/* ... OK, we'd better think about it */
-			gen_partprune_steps(subpart, partprunequal, PARTTARGET_EXEC,
-								&context);
+			gen_partprune_steps(subpart, partprunequal, available_rels,
+								PARTTARGET_EXEC, &context);
 
 			if (context.contradictory)
 			{
@@ -587,11 +773,14 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			/*
 			 * Detect which exec Params actually got used; the fact that some
 			 * were in available clauses doesn't mean we actually used them.
-			 * Skip per-scan pruning if there are none.
 			 */
 			execparamids = get_partkey_exec_paramids(exec_pruning_steps);
 
-			if (bms_is_empty(execparamids))
+			/*
+			 * Skip per-scan pruning if there are none used exec Params and
+			 * there are none available Vars.
+			 */
+			if (bms_is_empty(execparamids) && !context.has_vars)
 				exec_pruning_steps = NIL;
 		}
 		else
@@ -703,6 +892,9 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  *		Process 'clauses' (typically a rel's baserestrictinfo list of clauses)
  *		and create a list of "partition pruning steps".
  *
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
+ *
  * 'target' tells whether to generate pruning steps for planning (use
  * immutable clauses only), or for executor startup (use any allowable
  * clause except ones containing PARAM_EXEC Params), or for executor
@@ -712,12 +904,13 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  * some subsidiary flags; see the GeneratePruningStepsContext typedef.
  */
 static void
-gen_partprune_steps(RelOptInfo *rel, List *clauses, PartClauseTarget target,
-					GeneratePruningStepsContext *context)
+gen_partprune_steps(RelOptInfo *rel, List *clauses, Bitmapset *available_rels,
+					PartClauseTarget target, GeneratePruningStepsContext *context)
 {
 	/* Initialize all output values to zero/false/NULL */
 	memset(context, 0, sizeof(GeneratePruningStepsContext));
 	context->rel = rel;
+	context->available_rels = available_rels;
 	context->target = target;
 
 	/*
@@ -773,7 +966,7 @@ prune_append_rel_partitions(RelOptInfo *rel)
 	 * If the clauses are found to be contradictory, we can return the empty
 	 * set.
 	 */
-	gen_partprune_steps(rel, clauses, PARTTARGET_PLANNER,
+	gen_partprune_steps(rel, clauses, NULL, PARTTARGET_PLANNER,
 						&gcontext);
 	if (gcontext.contradictory)
 		return NULL;
@@ -1957,9 +2150,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) expr))
+			if (contain_forbidden_var_clause((Node *) expr, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -2155,9 +2349,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) rightop))
+			if (contain_forbidden_var_clause((Node *) rightop, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -3727,3 +3922,54 @@ partkey_datum_from_expr(PartitionPruneContext *context,
 		*value = ExecEvalExprSwitchContext(exprstate, ectx, isnull);
 	}
 }
+
+/*
+ * contain_forbidden_var_clause
+ *	  Recursively scan a clause to discover whether it contains any Var nodes
+ *	  (of the current query level) that do not belong to relations in
+ *	  context->available_rels.
+ *
+ *	  Returns true if any such varnode found.
+ *
+ * Does not examine subqueries, therefore must only be used after reduction
+ * of sublinks to subplans!
+ */
+static bool
+contain_forbidden_var_clause(Node *node, GeneratePruningStepsContext *context)
+{
+	return contain_forbidden_var_clause_walker(node, context);
+}
+
+static bool
+contain_forbidden_var_clause_walker(Node *node, GeneratePruningStepsContext *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		*var = (Var *) node;
+
+		if (var->varlevelsup != 0)
+			return false;
+
+		if (!bms_is_member(var->varno, context->available_rels))
+			return true;		/* abort the tree traversal and return true */
+
+		context->has_vars = true;
+
+		if (context->target != PARTTARGET_EXEC)
+			return true;		/* abort the tree traversal and return true */
+
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+		return true;
+	if (IsA(node, PlaceHolderVar))
+	{
+		if (((PlaceHolderVar *) node)->phlevelsup == 0)
+			return true;		/* abort the tree traversal and return true */
+		/* else fall through to check the contained expr */
+	}
+	return expression_tree_walker(node, contain_forbidden_var_clause_walker,
+								  (void *) context);
+}
diff --git a/src/include/executor/execPartition.h b/src/include/executor/execPartition.h
index 15ec869ac8..720bcc1149 100644
--- a/src/include/executor/execPartition.h
+++ b/src/include/executor/execPartition.h
@@ -121,11 +121,26 @@ typedef struct PartitionPruneState
 	PartitionPruningData *partprunedata[FLEXIBLE_ARRAY_MEMBER];
 } PartitionPruneState;
 
+/*
+ * JoinPartitionPruneState - State object required for plan nodes to perform
+ * join partition pruning.
+ */
+typedef struct JoinPartitionPruneState
+{
+	PartitionPruneState *part_prune_state;
+	int			paramid;
+	int			nplans;
+	bool		finished;
+	Bitmapset  *part_prune_result;
+} JoinPartitionPruneState;
+
 extern PartitionPruneState *ExecInitPartitionPruning(PlanState *planstate,
 													 int n_total_subplans,
 													 PartitionPruneInfo *pruneinfo,
 													 Bitmapset **initially_valid_subplans);
+extern List *ExecInitJoinpartpruneList(PlanState *planstate, List *joinpartprune_info_list);
 extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-										   bool initial_prune);
+										   bool initial_prune,
+										   PlanState *planstate);
 
 #endif							/* EXECPARTITION_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 5d7f17dee0..0aeafcabff 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2678,6 +2678,9 @@ typedef struct HashState
 
 	/* Parallel hash state. */
 	struct ParallelHashJoinState *parallel_state;
+
+	/* Infos for join partition pruning. */
+	List *joinpartprune_state_list;
 } HashState;
 
 /* ----------------
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index ed85dc7414..d066b6105c 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,9 @@ struct PlannerInfo
 	/* not-yet-assigned NestLoopParams */
 	List	   *curOuterParams;
 
+	/* a stack of JoinPartitionPruneInfos */
+	List	   *join_partition_prune_candidates;
+
 	/*
 	 * These fields are workspace for setrefs.c.  Each is an array
 	 * corresponding to glob->subplans.  (We could probably teach
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 24d46c76dc..00058a735e 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -276,6 +276,9 @@ typedef struct Append
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } Append;
 
 /* ----------------
@@ -311,6 +314,9 @@ typedef struct MergeAppend
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } MergeAppend;
 
 /* ----------------
@@ -1207,6 +1213,7 @@ typedef struct Hash
 	bool		skewInherit;	/* is outer join rel an inheritance tree? */
 	/* all other info is in the parent HashJoin node */
 	Cardinality rows_total;		/* estimate total rows if parallel_aware */
+	List	   *joinpartprune_info_list;	/* infos for join partition pruning */
 } Hash;
 
 /* ----------------
@@ -1553,6 +1560,35 @@ typedef struct PartitionPruneStepCombine
 	List	   *source_stepids;
 } PartitionPruneStepCombine;
 
+/*
+ * JoinPartitionPruneCandidateInfo - Information required to build
+ * JoinPartitionPruneInfos.
+ */
+typedef struct JoinPartitionPruneCandidateInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	List	   *joinrestrictinfo;
+	Bitmapset  *inner_relids;
+	double		inner_rows;
+	List	   *joinpartprune_info_list;
+} JoinPartitionPruneCandidateInfo;
+
+/*
+ * JoinPartitionPruneInfo - Details required to allow the executor to prune
+ * partitions during join.
+ */
+typedef struct JoinPartitionPruneInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	PartitionPruneInfo *part_prune_info;
+	int			paramid;
+	int			nplans;
+} JoinPartitionPruneInfo;
+
 
 /*
  * Plan invalidation info
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 6d50afbf74..52de844f6d 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -211,5 +211,9 @@ extern void set_foreign_size_estimates(PlannerInfo *root, RelOptInfo *rel);
 extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *target);
 extern double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 								   Path *bitmapqual, int loop_count, Cost *cost, double *tuple);
+extern double compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+									 Cost append_total_cost, int append_nplans,
+									 Relids inner_relids, double inner_rows,
+									 List *prunequal);
 
 #endif							/* COST_H */
diff --git a/src/include/partitioning/partprune.h b/src/include/partitioning/partprune.h
index 8636e04e37..899aa61b34 100644
--- a/src/include/partitioning/partprune.h
+++ b/src/include/partitioning/partprune.h
@@ -19,6 +19,8 @@
 
 struct PlannerInfo;				/* avoid including pathnodes.h here */
 struct RelOptInfo;
+struct Path;
+struct JoinPath;
 
 
 /*
@@ -73,7 +75,15 @@ typedef struct PartitionPruneContext
 extern PartitionPruneInfo *make_partition_pruneinfo(struct PlannerInfo *root,
 													struct RelOptInfo *parentrel,
 													List *subpaths,
-													List *prunequal);
+													List *prunequal,
+													Bitmapset *available_rels);
+extern Bitmapset *make_join_partition_pruneinfos(struct PlannerInfo *root,
+												 struct RelOptInfo *parentrel,
+												 struct Path *best_path,
+												 List *subpaths);
+extern void prepare_join_partition_prune_candidate(struct PlannerInfo *root,
+												   struct JoinPath *jpath);
+extern List *get_join_partition_prune_candidate(struct PlannerInfo *root);
 extern Bitmapset *prune_append_rel_partitions(struct RelOptInfo *rel);
 extern Bitmapset *get_matching_partitions(PartitionPruneContext *context,
 										  List *pruning_steps);
diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 9a4c48c055..a08e7a1f0a 100644
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3003,6 +3003,92 @@ order by tbl1.col1, tprt.col1;
 ------+------
 (0 rows)
 
+-- join partition pruning
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+                         explain_join_partition_pruning                         
+--------------------------------------------------------------------------------
+ Hash Right Join (actual rows=2 loops=1)
+   Output: p1.col1, p2.col1, t.col1
+   Hash Cond: ((p1.col1 = t.col1) AND (p2.col1 = t.col1))
+   ->  Hash Join (actual rows=3 loops=1)
+         Output: p1.col1, p2.col1
+         Hash Cond: (p1.col1 = p2.col1)
+         ->  Append (actual rows=3 loops=1)
+               Join Partition Pruning: $0
+               ->  Seq Scan on public.tprt_1 p1_1 (never executed)
+                     Output: p1_1.col1
+               ->  Seq Scan on public.tprt_2 p1_2 (actual rows=3 loops=1)
+                     Output: p1_2.col1
+               ->  Seq Scan on public.tprt_3 p1_3 (never executed)
+                     Output: p1_3.col1
+               ->  Seq Scan on public.tprt_4 p1_4 (never executed)
+                     Output: p1_4.col1
+               ->  Seq Scan on public.tprt_5 p1_5 (never executed)
+                     Output: p1_5.col1
+               ->  Seq Scan on public.tprt_6 p1_6 (never executed)
+                     Output: p1_6.col1
+         ->  Hash (actual rows=3 loops=1)
+               Output: p2.col1
+               Buckets: 1024  Batches: 1  Memory Usage: NkB
+               ->  Append (actual rows=3 loops=1)
+                     Join Partition Pruning: $1
+                     ->  Seq Scan on public.tprt_1 p2_1 (never executed)
+                           Output: p2_1.col1
+                     ->  Seq Scan on public.tprt_2 p2_2 (actual rows=3 loops=1)
+                           Output: p2_2.col1
+                     ->  Seq Scan on public.tprt_3 p2_3 (never executed)
+                           Output: p2_3.col1
+                     ->  Seq Scan on public.tprt_4 p2_4 (never executed)
+                           Output: p2_4.col1
+                     ->  Seq Scan on public.tprt_5 p2_5 (never executed)
+                           Output: p2_5.col1
+                     ->  Seq Scan on public.tprt_6 p2_6 (never executed)
+                           Output: p2_6.col1
+   ->  Hash (actual rows=2 loops=1)
+         Output: t.col1
+         Buckets: 1024  Batches: 1  Memory Usage: NkB
+         Partition Prune: $0, $1
+         ->  Seq Scan on public.tbl1 t (actual rows=2 loops=1)
+               Output: t.col1
+(43 rows)
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+ col1 | col1 | col1 
+------+------+------
+  501 |  501 |  501
+  505 |  505 |  505
+(2 rows)
+
 drop table tbl1, tprt;
 -- Test with columns defined in varying orders between each level
 create table part_abc (a int not null, b int not null, c int not null) partition by list (a);
diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index 7bf3920827..fc5982edcf 100644
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -727,6 +727,45 @@ select tbl1.col1, tprt.col1 from tbl1
 inner join tprt on tbl1.col1 = tprt.col1
 order by tbl1.col1, tprt.col1;
 
+-- join partition pruning
+
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+
 drop table tbl1, tprt;
 
 -- Test with columns defined in varying orders between each level
-- 
2.31.0

From 470ebcee95f4c0b162b6826ce840bf17d8df5266 Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Mon, 14 Aug 2023 14:55:26 +0800
Subject: [PATCH v5] Support run-time partition pruning for hash join

If we have a hash join with an Append node on the outer side, something
like

 Hash Join
   Hash Cond: (pt.a = t.a)
   ->  Append
         ->  Seq Scan on pt_p1 pt_1
         ->  Seq Scan on pt_p2 pt_2
         ->  Seq Scan on pt_p3 pt_3
   ->  Hash
         ->  Seq Scan on t

We can actually prune those subnodes of the Append that cannot possibly
contain any matching tuples from the other side of the join.  To do
that, when building the Hash table, for each row from the inner side we
can compute the minimum set of subnodes that can possibly match the join
condition.  When we have built the Hash table and start to execute the
Append node, we should have known which subnodes are survived and thus
can skip other subnodes.

This patch implements this idea.
---
 src/backend/commands/explain.c                |  61 ++++
 src/backend/executor/execPartition.c          | 127 +++++++-
 src/backend/executor/nodeAppend.c             |  32 +-
 src/backend/executor/nodeHash.c               |  75 +++++
 src/backend/executor/nodeHashjoin.c           |  10 +
 src/backend/executor/nodeMergeAppend.c        |  22 +-
 src/backend/optimizer/path/costsize.c         | 106 +++++++
 src/backend/optimizer/plan/createplan.c       |  49 ++-
 src/backend/optimizer/plan/setrefs.c          |  61 ++++
 src/backend/partitioning/partprune.c          | 298 ++++++++++++++++--
 src/include/executor/execPartition.h          |  17 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/pathnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |  36 +++
 src/include/optimizer/cost.h                  |   4 +
 src/include/partitioning/partprune.h          |  12 +-
 src/test/regress/expected/partition_prune.out |  86 +++++
 src/test/regress/sql/partition_prune.sql      |  39 +++
 18 files changed, 992 insertions(+), 49 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index f1d71bc54e..c51cf6beb6 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -18,6 +18,7 @@
 #include "commands/createas.h"
 #include "commands/defrem.h"
 #include "commands/prepare.h"
+#include "executor/execPartition.h"
 #include "executor/nodeHash.h"
 #include "foreign/fdwapi.h"
 #include "jit/jit.h"
@@ -118,6 +119,9 @@ static void show_instrumentation_count(const char *qlabel, int which,
 									   PlanState *planstate, ExplainState *es);
 static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
 static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
+static void show_join_pruning_result_info(Bitmapset *join_prune_paramids,
+										  ExplainState *es);
+static void show_joinpartprune_info(HashState *hashstate, ExplainState *es);
 static const char *explain_get_index_name(Oid indexId);
 static void show_buffer_usage(ExplainState *es, const BufferUsage *usage,
 							  bool planning);
@@ -2057,9 +2061,17 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			show_incremental_sort_info(castNode(IncrementalSortState, planstate),
 									   es);
 			break;
+		case T_Append:
+			if (es->verbose)
+				show_join_pruning_result_info(((Append *) plan)->join_prune_paramids,
+											  es);
+			break;
 		case T_MergeAppend:
 			show_merge_append_keys(castNode(MergeAppendState, planstate),
 								   ancestors, es);
+			if (es->verbose)
+				show_join_pruning_result_info(((MergeAppend *) plan)->join_prune_paramids,
+											  es);
 			break;
 		case T_Result:
 			show_upper_qual((List *) ((Result *) plan)->resconstantqual,
@@ -2075,6 +2087,8 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			break;
 		case T_Hash:
 			show_hash_info(castNode(HashState, planstate), es);
+			if (es->verbose)
+				show_joinpartprune_info(castNode(HashState, planstate), es);
 			break;
 		case T_Memoize:
 			show_memoize_info(castNode(MemoizeState, planstate), ancestors,
@@ -3515,6 +3529,53 @@ show_eval_params(Bitmapset *bms_params, ExplainState *es)
 		ExplainPropertyList("Params Evaluated", params, es);
 }
 
+/*
+ * Show join partition pruning results at Append/MergeAppend nodes.
+ */
+static void
+show_join_pruning_result_info(Bitmapset *join_prune_paramids, ExplainState *es)
+{
+	int			paramid = -1;
+	List	   *params = NIL;
+
+	if (bms_is_empty(join_prune_paramids))
+		return;
+
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Join Partition Pruning", params, es);
+}
+
+/*
+ * Show join partition pruning infos at Hash nodes.
+ */
+static void
+show_joinpartprune_info(HashState *hashstate, ExplainState *es)
+{
+	List	   *params = NIL;
+	ListCell   *lc;
+
+	if (!hashstate->joinpartprune_state_list)
+		return;
+
+	foreach(lc, hashstate->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", jpstate->paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Partition Prune", params, es);
+}
+
 /*
  * Fetch the name of an index in an EXPLAIN
  *
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index f6c34328b8..35a9149a39 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -199,6 +199,8 @@ static void find_matching_subplans_recurse(PartitionPruningData *prunedata,
 										   PartitionedRelPruningData *pprune,
 										   bool initial_prune,
 										   Bitmapset **validsubplans);
+static bool get_join_prune_matching_subplans(PlanState *planstate,
+											 Bitmapset **partset);
 
 
 /*
@@ -1806,7 +1808,7 @@ ExecInitPartitionPruning(PlanState *planstate,
 	 * Perform an initial partition prune pass, if required.
 	 */
 	if (prunestate->do_initial_prune)
-		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true);
+		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true, NULL);
 	else
 	{
 		/* No pruning, so we'll need to initialize all subplans */
@@ -1836,6 +1838,37 @@ ExecInitPartitionPruning(PlanState *planstate,
 	return prunestate;
 }
 
+/*
+ * ExecInitJoinpartpruneList
+ *		Initialize data structures needed for join partition pruning
+ */
+List *
+ExecInitJoinpartpruneList(PlanState *planstate,
+						  List *joinpartprune_info_list)
+{
+	ListCell   *lc;
+	List	   *result = NIL;
+
+	foreach(lc, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(lc);
+		JoinPartitionPruneState *jpstate = palloc(sizeof(JoinPartitionPruneState));
+
+		jpstate->part_prune_state =
+			CreatePartitionPruneState(planstate, jpinfo->part_prune_info);
+		Assert(jpstate->part_prune_state->do_exec_prune);
+
+		jpstate->paramid = jpinfo->paramid;
+		jpstate->nplans = jpinfo->nplans;
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+
+		result = lappend(result, jpstate);
+	}
+
+	return result;
+}
+
 /*
  * CreatePartitionPruneState
  *		Build the data structure required for calling ExecFindMatchingSubPlans
@@ -2273,7 +2306,9 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
 /*
  * ExecFindMatchingSubPlans
  *		Determine which subplans match the pruning steps detailed in
- *		'prunestate' for the current comparison expression values.
+ *		'prunestate' if any for the current comparison expression values, and
+ *		meanwhile match the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.
  *
  * Pass initial_prune if PARAM_EXEC Params cannot yet be evaluated.  This
  * differentiates the initial executor-time pruning step from later
@@ -2281,11 +2316,30 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
  */
 Bitmapset *
 ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-						 bool initial_prune)
+						 bool initial_prune,
+						 PlanState *planstate)
 {
 	Bitmapset  *result = NULL;
 	MemoryContext oldcontext;
 	int			i;
+	Bitmapset  *join_prune_partset = NULL;
+	bool		do_join_prune;
+
+	/* Retrieve the join partition pruning results if any */
+	do_join_prune =
+		get_join_prune_matching_subplans(planstate, &join_prune_partset);
+
+	/*
+	 * Either we're here on partition prune done according to the pruning steps
+	 * detailed in 'prunestate', or we have done join partition prune.
+	 */
+	Assert(do_join_prune || prunestate != NULL);
+
+	/*
+	 * If there is no 'prunestate', then rely entirely on join pruning.
+	 */
+	if (prunestate == NULL)
+		return join_prune_partset;
 
 	/*
 	 * Either we're here on the initial prune done during pruning
@@ -2326,6 +2380,10 @@ ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
 	/* Add in any subplans that partition pruning didn't account for */
 	result = bms_add_members(result, prunestate->other_subplans);
 
+	/* Intersect join partition pruning results */
+	if (do_join_prune)
+		result = bms_intersect(result, join_prune_partset);
+
 	MemoryContextSwitchTo(oldcontext);
 
 	/* Copy result out of the temp context before we reset it */
@@ -2396,3 +2454,66 @@ find_matching_subplans_recurse(PartitionPruningData *prunedata,
 		}
 	}
 }
+
+/*
+ * get_join_prune_matching_subplans
+ *		Retrieve the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.  Return true if we can
+ *		do join partition pruning, otherwise return false.
+ *
+ * Adds valid (non-prunable) subplan IDs to *partset
+ */
+static bool
+get_join_prune_matching_subplans(PlanState *planstate, Bitmapset **partset)
+{
+	Bitmapset  *join_prune_paramids;
+	int			nplans;
+	int			paramid;
+
+	if (planstate == NULL)
+		return false;
+
+	if (IsA(planstate, AppendState))
+	{
+		join_prune_paramids =
+			((Append *) planstate->plan)->join_prune_paramids;
+		nplans = ((AppendState *) planstate)->as_nplans;
+	}
+	else if (IsA(planstate, MergeAppendState))
+	{
+		join_prune_paramids =
+			((MergeAppend *) planstate->plan)->join_prune_paramids;
+		nplans = ((MergeAppendState *) planstate)->ms_nplans;
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(planstate));
+		return false;
+	}
+
+	if (bms_is_empty(join_prune_paramids))
+		return false;
+
+	Assert(nplans > 0);
+	*partset = bms_add_range(NULL, 0, nplans - 1);
+
+	paramid = -1;
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		ParamExecData *param;
+		JoinPartitionPruneState *jpstate;
+
+		param = &(planstate->state->es_param_exec_vals[paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		jpstate = (JoinPartitionPruneState *) DatumGetPointer(param->value);
+
+		if (jpstate != NULL)
+			*partset = bms_intersect(*partset, jpstate->part_prune_result);
+		else	/* the Hash node for this pruning has not been executed */
+			elog(WARNING, "Join partition pruning $%d has not been performed yet.",
+				 paramid);
+	}
+
+	return true;
+}
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 609df6b9e6..c8dd8583d2 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -151,11 +151,13 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill as_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill as_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 		{
 			appendstate->as_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 			appendstate->as_valid_subplans_identified = true;
@@ -170,10 +172,18 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		appendstate->as_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
-		appendstate->as_valid_subplans_identified = true;
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		appendstate->as_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill as_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+		{
+			appendstate->as_valid_subplans = validsubplans;
+			appendstate->as_valid_subplans_identified = true;
+		}
 	}
 
 	/*
@@ -580,7 +590,7 @@ choose_next_subplan_locally(AppendState *node)
 		else if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 		}
 
@@ -647,7 +657,7 @@ choose_next_subplan_for_leader(AppendState *node)
 		if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 
 			/*
@@ -723,7 +733,7 @@ choose_next_subplan_for_worker(AppendState *node)
 	else if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		mark_invalid_subplans_as_finished(node);
@@ -876,7 +886,7 @@ ExecAppendAsyncBegin(AppendState *node)
 	if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		classify_matching_subplans(node);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index e72f0986c2..9ca8bf49d9 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -31,6 +31,7 @@
 #include "catalog/pg_statistic.h"
 #include "commands/tablespace.h"
 #include "executor/execdebug.h"
+#include "executor/execPartition.h"
 #include "executor/hashjoin.h"
 #include "executor/nodeHash.h"
 #include "executor/nodeHashjoin.h"
@@ -48,6 +49,8 @@ static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable);
+static void ExecJoinPartitionPrune(HashState *node);
+static void ExecStoreJoinPartitionPruneResult(HashState *node);
 static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node,
 								  int mcvsToUse);
 static void ExecHashSkewTableInsert(HashJoinTable hashtable,
@@ -189,8 +192,14 @@ MultiExecPrivateHash(HashState *node)
 			}
 			hashtable->totalTuples += 1;
 		}
+
+		/* Perform join partition pruning */
+		ExecJoinPartitionPrune(node);
 	}
 
+	/* Store the surviving partitions for Append/MergeAppend nodes */
+	ExecStoreJoinPartitionPruneResult(node);
+
 	/* resize the hash table if needed (NTUP_PER_BUCKET exceeded) */
 	if (hashtable->nbuckets != hashtable->nbuckets_optimal)
 		ExecHashIncreaseNumBuckets(hashtable);
@@ -401,6 +410,12 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	hashstate->hashkeys =
 		ExecInitExprList(node->hashkeys, (PlanState *) hashstate);
 
+	/*
+	 * initialize join partition pruning infos
+	 */
+	hashstate->joinpartprune_state_list =
+		ExecInitJoinpartpruneList(&hashstate->ps, node->joinpartprune_info_list);
+
 	return hashstate;
 }
 
@@ -1601,6 +1616,56 @@ ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable)
 	}
 }
 
+/*
+ * ExecJoinPartitionPrune
+ *		Perform join partition pruning at this join for each
+ *		JoinPartitionPruneState.
+ */
+static void
+ExecJoinPartitionPrune(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		Bitmapset	   *matching_subPlans;
+
+		if (jpstate->finished)
+			continue;
+
+		matching_subPlans =
+			ExecFindMatchingSubPlans(jpstate->part_prune_state, false, NULL);
+		jpstate->part_prune_result =
+			bms_add_members(jpstate->part_prune_result, matching_subPlans);
+
+		if (bms_num_members(jpstate->part_prune_result) == jpstate->nplans)
+			jpstate->finished = true;
+	}
+}
+
+/*
+ * ExecStoreJoinPartitionPruneResult
+ *		For each JoinPartitionPruneState, store the set of surviving partitions
+ *		to make it available for the Append/MergeAppend node.
+ */
+static void
+ExecStoreJoinPartitionPruneResult(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		ParamExecData	   *param;
+
+		param = &(node->ps.state->es_param_exec_vals[jpstate->paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		param->value = PointerGetDatum(jpstate);
+	}
+}
+
 /*
  * ExecHashTableInsert
  *		insert a tuple into the hash table depending on the hash value
@@ -2345,6 +2410,16 @@ void
 ExecReScanHash(HashState *node)
 {
 	PlanState  *outerPlan = outerPlanState(node);
+	ListCell   *lc;
+
+	/* reset the state in JoinPartitionPruneStates */
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+	}
 
 	/*
 	 * if chgParam of subnode is not null then plan will be re-scanned by
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 25a2d78f15..ddca824206 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -311,6 +311,16 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 					 */
 					node->hj_FirstOuterTupleSlot = NULL;
 				}
+				else if (hashNode->joinpartprune_state_list != NIL)
+				{
+					/*
+					 * Give the hash node a chance to run join partition
+					 * pruning if there is any JoinPartitionPruneState that can
+					 * be evaluated at it.  So do not apply the empty-outer
+					 * optimization in this case.
+					 */
+					node->hj_FirstOuterTupleSlot = NULL;
+				}
 				else if (HJ_FILL_OUTER(node) ||
 						 (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
 						  !node->hj_OuterNotEmpty))
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 21b5726e6e..9eb276abc8 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -99,11 +99,13 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill ms_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill ms_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 			mergestate->ms_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 	}
 	else
@@ -115,9 +117,15 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		mergestate->ms_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		mergestate->ms_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill ms_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+			mergestate->ms_valid_subplans = validsubplans;
 	}
 
 	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
@@ -218,7 +226,7 @@ ExecMergeAppend(PlanState *pstate)
 		 */
 		if (node->ms_valid_subplans == NULL)
 			node->ms_valid_subplans =
-				ExecFindMatchingSubPlans(node->ms_prune_state, false);
+				ExecFindMatchingSubPlans(node->ms_prune_state, false, &node->ps);
 
 		/*
 		 * First time through: pull the first tuple from each valid subplan,
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index d6ceafd51c..9bdc88a9db 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -173,6 +173,10 @@ static void get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
 static bool has_indexed_join_quals(NestPath *path);
 static double approx_tuple_count(PlannerInfo *root, JoinPath *path,
 								 List *quals);
+static double get_joinrel_matching_outer_size(PlannerInfo *root,
+											  RelOptInfo *outer_rel,
+											  Relids inner_relids,
+											  List *restrictlist);
 static double calc_joinrel_size_estimate(PlannerInfo *root,
 										 RelOptInfo *joinrel,
 										 RelOptInfo *outer_rel,
@@ -5380,6 +5384,61 @@ get_parameterized_joinrel_size(PlannerInfo *root, RelOptInfo *rel,
 	return nrows;
 }
 
+/*
+ * get_joinrel_matching_outer_size
+ *		Make a size estimate for the outer side that matches the inner side.
+ */
+static double
+get_joinrel_matching_outer_size(PlannerInfo *root,
+								RelOptInfo *outer_rel,
+								Relids inner_relids,
+								List *restrictlist)
+{
+	double		nrows;
+	Selectivity fkselec;
+	Selectivity jselec;
+	SpecialJoinInfo *sjinfo;
+	SpecialJoinInfo sjinfo_data;
+
+	sjinfo = &sjinfo_data;
+	sjinfo->type = T_SpecialJoinInfo;
+	sjinfo->min_lefthand = outer_rel->relids;
+	sjinfo->min_righthand = inner_relids;
+	sjinfo->syn_lefthand = outer_rel->relids;
+	sjinfo->syn_righthand = inner_relids;
+	sjinfo->jointype = JOIN_SEMI;
+	sjinfo->ojrelid = 0;
+	sjinfo->commute_above_l = NULL;
+	sjinfo->commute_above_r = NULL;
+	sjinfo->commute_below_l = NULL;
+	sjinfo->commute_below_r = NULL;
+	/* we don't bother trying to make the remaining fields valid */
+	sjinfo->lhs_strict = false;
+	sjinfo->semi_can_btree = false;
+	sjinfo->semi_can_hash = false;
+	sjinfo->semi_operators = NIL;
+	sjinfo->semi_rhs_exprs = NIL;
+
+	fkselec = get_foreign_key_join_selectivity(root,
+											   outer_rel->relids,
+											   inner_relids,
+											   sjinfo,
+											   &restrictlist);
+	jselec = clauselist_selectivity(root,
+									restrictlist,
+									0,
+									sjinfo->jointype,
+									sjinfo);
+
+	nrows = outer_rel->rows * fkselec * jselec;
+	nrows = clamp_row_est(nrows);
+
+	/* For safety, make sure result is not more than the base estimate */
+	if (nrows > outer_rel->rows)
+		nrows = outer_rel->rows;
+	return nrows;
+}
+
 /*
  * calc_joinrel_size_estimate
  *		Workhorse for set_joinrel_size_estimates and
@@ -6495,3 +6554,50 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel, Path *bitmapqual,
 
 	return pages_fetched;
 }
+
+/*
+ * compute_partprune_cost
+ *		Compute the overhead of join partition pruning.
+ */
+double
+compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+					   Cost append_total_cost, int append_nplans,
+					   Relids inner_relids, double inner_rows,
+					   List *prunequal)
+{
+	Cost		prune_cost;
+	Cost		saved_cost;
+	double		matching_outer_rows;
+	double		unmatched_nplans;
+
+	switch (appendrel->part_scheme->strategy)
+	{
+
+		case PARTITION_STRATEGY_LIST:
+		case PARTITION_STRATEGY_RANGE:
+			prune_cost = cpu_operator_cost * LOG2(append_nplans) * inner_rows;
+			break;
+		case PARTITION_STRATEGY_HASH:
+			prune_cost = cpu_operator_cost * append_nplans * inner_rows;
+			break;
+		default:
+			elog(ERROR, "unexpected partition strategy: %d",
+				 (int) appendrel->part_scheme->strategy);
+			break;
+	}
+
+	matching_outer_rows =
+		get_joinrel_matching_outer_size(root,
+										appendrel,
+										inner_relids,
+										prunequal);
+
+	/*
+	 * We assume that each outer joined row occupies one new partition.  This
+	 * is really the worst case.
+	 */
+	unmatched_nplans = append_nplans - Min(matching_outer_rows, append_nplans);
+	saved_cost = (unmatched_nplans / append_nplans) * append_total_cost;
+
+	return prune_cost - saved_cost;
+}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 34ca6d4ac2..308ff452d3 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -242,7 +242,8 @@ static Hash *make_hash(Plan *lefttree,
 					   List *hashkeys,
 					   Oid skewTable,
 					   AttrNumber skewColumn,
-					   bool skewInherit);
+					   bool skewInherit,
+					   List *joinpartprune_info_list);
 static MergeJoin *make_mergejoin(List *tlist,
 								 List *joinclauses, List *otherclauses,
 								 List *mergeclauses,
@@ -342,6 +343,7 @@ create_plan(PlannerInfo *root, Path *best_path)
 	/* Initialize this module's workspace in PlannerInfo */
 	root->curOuterRels = NULL;
 	root->curOuterParams = NIL;
+	root->join_partition_prune_candidates = NIL;
 
 	/* Recursively process the path tree, demanding the correct tlist result */
 	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
@@ -369,6 +371,8 @@ create_plan(PlannerInfo *root, Path *best_path)
 	if (root->curOuterParams != NIL)
 		elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
 
+	Assert(root->join_partition_prune_candidates == NIL);
+
 	/*
 	 * Reset plan_params to ensure param IDs used for nestloop params are not
 	 * re-used later
@@ -1223,6 +1227,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	int			nasyncplans = 0;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 	int			nodenumsortkeys = 0;
 	AttrNumber *nodeSortColIdx = NULL;
 	Oid		   *nodeSortOperators = NULL;
@@ -1377,6 +1382,8 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1399,13 +1406,20 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 			partpruneinfo =
 				make_partition_pruneinfo(root, rel,
 										 best_path->subpaths,
-										 prunequal);
+										 prunequal,
+										 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	plan->appendplans = subplans;
 	plan->nasyncplans = nasyncplans;
 	plan->first_partial_plan = best_path->first_partial_path;
 	plan->part_prune_info = partpruneinfo;
+	plan->join_prune_paramids = join_prune_paramids;
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -1445,6 +1459,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	ListCell   *subpaths;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 
 	/*
 	 * We don't have the actual creation of the MergeAppend node split out
@@ -1541,6 +1556,8 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1554,11 +1571,18 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		if (prunequal != NIL)
 			partpruneinfo = make_partition_pruneinfo(root, rel,
 													 best_path->subpaths,
-													 prunequal);
+													 prunequal,
+													 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	node->mergeplans = subplans;
 	node->part_prune_info = partpruneinfo;
+	node->join_prune_paramids = join_prune_paramids;
 
 	/*
 	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
@@ -4734,6 +4758,13 @@ create_hashjoin_plan(PlannerInfo *root,
 	AttrNumber	skewColumn = InvalidAttrNumber;
 	bool		skewInherit = false;
 	ListCell   *lc;
+	List	   *joinpartprune_info_list;
+
+	/*
+	 * Collect information required to build JoinPartitionPruneInfos at this
+	 * join.
+	 */
+	prepare_join_partition_prune_candidate(root, &best_path->jpath);
 
 	/*
 	 * HashJoin can project, so we don't have to demand exact tlists from the
@@ -4745,6 +4776,11 @@ create_hashjoin_plan(PlannerInfo *root,
 	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
 									 (best_path->num_batches > 1) ? CP_SMALL_TLIST : 0);
 
+	/*
+	 * Retrieve all the JoinPartitionPruneInfos for this join.
+	 */
+	joinpartprune_info_list = get_join_partition_prune_candidate(root);
+
 	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
 									 CP_SMALL_TLIST);
 
@@ -4850,7 +4886,8 @@ create_hashjoin_plan(PlannerInfo *root,
 						  inner_hashkeys,
 						  skewTable,
 						  skewColumn,
-						  skewInherit);
+						  skewInherit,
+						  joinpartprune_info_list);
 
 	/*
 	 * Set Hash node's startup & total costs equal to total cost of input
@@ -5977,7 +6014,8 @@ make_hash(Plan *lefttree,
 		  List *hashkeys,
 		  Oid skewTable,
 		  AttrNumber skewColumn,
-		  bool skewInherit)
+		  bool skewInherit,
+		  List *joinpartprune_info_list)
 {
 	Hash	   *node = makeNode(Hash);
 	Plan	   *plan = &node->plan;
@@ -5991,6 +6029,7 @@ make_hash(Plan *lefttree,
 	node->skewTable = skewTable;
 	node->skewColumn = skewColumn;
 	node->skewInherit = skewInherit;
+	node->joinpartprune_info_list = joinpartprune_info_list;
 
 	return node;
 }
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index fc3709510d..c416e7ccda 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -156,6 +156,11 @@ static Plan *set_mergeappend_references(PlannerInfo *root,
 										MergeAppend *mplan,
 										int rtoffset);
 static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_joinpartitionprune_references(PlannerInfo *root,
+											  List *joinpartprune_info_list,
+											  indexed_tlist *outer_itlist,
+											  int rtoffset,
+											  double num_exec);
 static Relids offset_relid_set(Relids relids, int rtoffset);
 static Node *fix_scan_expr(PlannerInfo *root, Node *node,
 						   int rtoffset, double num_exec);
@@ -1897,6 +1902,62 @@ set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset)
 
 	/* Hash nodes don't have their own quals */
 	Assert(plan->qual == NIL);
+
+	set_joinpartitionprune_references(root,
+									  hplan->joinpartprune_info_list,
+									  outer_itlist,
+									  rtoffset,
+									  NUM_EXEC_TLIST(plan));
+}
+
+/*
+ * set_joinpartitionprune_references
+ *	   Do set_plan_references processing on JoinPartitionPruneInfos
+ */
+static void
+set_joinpartitionprune_references(PlannerInfo *root,
+								  List *joinpartprune_info_list,
+								  indexed_tlist *outer_itlist,
+								  int rtoffset,
+								  double num_exec)
+{
+	ListCell   *l;
+
+	foreach(l, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(l);
+		ListCell   *l1;
+
+		foreach(l1, jpinfo->part_prune_info->prune_infos)
+		{
+			List	   *prune_infos = lfirst(l1);
+			ListCell   *l2;
+
+			foreach(l2, prune_infos)
+			{
+				PartitionedRelPruneInfo *pinfo = lfirst(l2);
+
+				pinfo->rtindex += rtoffset;
+
+				pinfo->initial_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->initial_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+				pinfo->exec_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->exec_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+			}
+		}
+	}
 }
 
 /*
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 3f31ecc956..d978093831 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -48,7 +48,9 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/cost.h"
 #include "optimizer/optimizer.h"
+#include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/restrictinfo.h"
 #include "parser/parsetree.h"
 #include "partitioning/partbounds.h"
 #include "partitioning/partprune.h"
@@ -103,15 +105,16 @@ typedef enum PartClauseTarget
  *
  * gen_partprune_steps() initializes and returns an instance of this struct.
  *
- * Note that has_mutable_op, has_mutable_arg, and has_exec_param are set if
- * we found any potentially-useful-for-pruning clause having those properties,
- * whether or not we actually used the clause in the steps list.  This
- * definition allows us to skip the PARTTARGET_EXEC pass in some cases.
+ * Note that has_mutable_op, has_mutable_arg, has_exec_param and has_vars are
+ * set if we found any potentially-useful-for-pruning clause having those
+ * properties, whether or not we actually used the clause in the steps list.
+ * This definition allows us to skip the PARTTARGET_EXEC pass in some cases.
  */
 typedef struct GeneratePruningStepsContext
 {
 	/* Copies of input arguments for gen_partprune_steps: */
 	RelOptInfo *rel;			/* the partitioned relation */
+	Bitmapset  *available_rels;	/* rels whose Vars may be used for pruning */
 	PartClauseTarget target;	/* use-case we're generating steps for */
 	/* Result data: */
 	List	   *steps;			/* list of PartitionPruneSteps */
@@ -119,6 +122,7 @@ typedef struct GeneratePruningStepsContext
 	bool		has_mutable_arg;	/* clauses include any mutable comparison
 									 * values, *other than* exec params */
 	bool		has_exec_param; /* clauses include any PARAM_EXEC params */
+	bool		has_vars;		/* clauses include any Vars from 'available_rels' */
 	bool		contradictory;	/* clauses were proven self-contradictory */
 	/* Working state: */
 	int			next_step_id;
@@ -144,8 +148,10 @@ static List *make_partitionedrel_pruneinfo(PlannerInfo *root,
 										   List *prunequal,
 										   Bitmapset *partrelids,
 										   int *relid_subplan_map,
+										   Bitmapset *available_rels,
 										   Bitmapset **matchedsubplans);
 static void gen_partprune_steps(RelOptInfo *rel, List *clauses,
+								Bitmapset *available_rels,
 								PartClauseTarget target,
 								GeneratePruningStepsContext *context);
 static List *gen_partprune_steps_internal(GeneratePruningStepsContext *context,
@@ -204,6 +210,10 @@ static PartClauseMatchStatus match_boolean_partition_clause(Oid partopfamily,
 static void partkey_datum_from_expr(PartitionPruneContext *context,
 									Expr *expr, int stateidx,
 									Datum *value, bool *isnull);
+static bool contain_forbidden_var_clause(Node *node,
+										 GeneratePruningStepsContext *context);
+static bool contain_forbidden_var_clause_walker(Node *node,
+												GeneratePruningStepsContext *context);
 
 
 /*
@@ -216,11 +226,14 @@ static void partkey_datum_from_expr(PartitionPruneContext *context,
  * 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).
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
  */
 PartitionPruneInfo *
 make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 						 List *subpaths,
-						 List *prunequal)
+						 List *prunequal,
+						 Bitmapset *available_rels)
 {
 	PartitionPruneInfo *pruneinfo;
 	Bitmapset  *allmatchedsubplans = NULL;
@@ -313,6 +326,7 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 												  prunequal,
 												  partrelids,
 												  relid_subplan_map,
+												  available_rels,
 												  &matchedsubplans);
 
 		/* When pruning is possible, record the matched subplans */
@@ -360,6 +374,184 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	return pruneinfo;
 }
 
+/*
+ * make_join_partition_pruneinfos
+ *		Builds one JoinPartitionPruneInfo for each join at which join partition
+ *		pruning is possible for this appendrel.
+ *
+ * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
+ * of scan paths for its child rels.
+ */
+Bitmapset *
+make_join_partition_pruneinfos(PlannerInfo *root, RelOptInfo *parentrel,
+							   Path *best_path, List *subpaths)
+{
+	Bitmapset  *result = NULL;
+	ListCell   *lc;
+
+	if (!IS_PARTITIONED_REL(parentrel))
+		return NULL;
+
+	foreach(lc, root->join_partition_prune_candidates)
+	{
+		JoinPartitionPruneCandidateInfo *candidate =
+			(JoinPartitionPruneCandidateInfo *) lfirst(lc);
+		PartitionPruneInfo *part_prune_info;
+		List	   *prunequal;
+		Relids		joinrelids;
+		ListCell   *l;
+		double		prune_cost;
+
+		if (candidate == NULL)
+			continue;
+
+		/*
+		 * Identify all joinclauses that are movable to this appendrel given
+		 * this inner side relids.  Only those clauses can be used for join
+		 * partition pruning.
+		 */
+		joinrelids = bms_union(parentrel->relids, candidate->inner_relids);
+		prunequal = NIL;
+		foreach(l, candidate->joinrestrictinfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+
+			if (join_clause_is_movable_into(rinfo,
+											parentrel->relids,
+											joinrelids))
+				prunequal = lappend(prunequal, rinfo);
+		}
+
+		if (prunequal == NIL)
+			continue;
+
+		/*
+		 * Check the overhead of this pruning
+		 */
+		prune_cost = compute_partprune_cost(root,
+											parentrel,
+											best_path->total_cost,
+											list_length(subpaths),
+											candidate->inner_relids,
+											candidate->inner_rows,
+											prunequal);
+		if (prune_cost > 0)
+			continue;
+
+		part_prune_info = make_partition_pruneinfo(root, parentrel,
+												   subpaths,
+												   prunequal,
+												   candidate->inner_relids);
+
+		if (part_prune_info)
+		{
+			JoinPartitionPruneInfo *jpinfo;
+
+			jpinfo = makeNode(JoinPartitionPruneInfo);
+
+			jpinfo->part_prune_info = part_prune_info;
+			jpinfo->paramid = assign_special_exec_param(root);
+			jpinfo->nplans = list_length(subpaths);
+
+			candidate->joinpartprune_info_list =
+				lappend(candidate->joinpartprune_info_list, jpinfo);
+
+			result = bms_add_member(result, jpinfo->paramid);
+		}
+	}
+
+	return result;
+}
+
+/*
+ * prepare_join_partition_prune_candidate
+ * 		Check if join partition pruning is possible at this join and if so
+ * 		collect information required to build JoinPartitionPruneInfos.
+ *
+ * Note that we may build more than one JoinPartitionPruneInfo at one join, for
+ * different Append/MergeAppend paths.
+ */
+void
+prepare_join_partition_prune_candidate(PlannerInfo *root, JoinPath *jpath)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+
+	if (!enable_partition_pruning)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now do not perform join partition pruning for parallel hashjoin.
+	 */
+	if (jpath->path.parallel_workers > 0)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * We cannot perform join partition pruning if the outer is the
+	 * non-nullable side.
+	 */
+	if (!(jpath->jointype == JOIN_INNER ||
+		  jpath->jointype == JOIN_SEMI ||
+		  jpath->jointype == JOIN_RIGHT ||
+		  jpath->jointype == JOIN_RIGHT_ANTI))
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now we only support HashJoin.
+	 */
+	if (jpath->path.pathtype != T_HashJoin)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	candidate = makeNode(JoinPartitionPruneCandidateInfo);
+	candidate->joinrestrictinfo = jpath->joinrestrictinfo;
+	candidate->inner_relids = jpath->innerjoinpath->parent->relids;
+	candidate->inner_rows = jpath->innerjoinpath->parent->rows;
+	candidate->joinpartprune_info_list = NIL;
+
+	root->join_partition_prune_candidates =
+		lappend(root->join_partition_prune_candidates, candidate);
+}
+
+/*
+ * get_join_partition_prune_candidate
+ *		Pop out the JoinPartitionPruneCandidateInfo for this join and retrieve
+ *		the JoinPartitionPruneInfos.
+ */
+List *
+get_join_partition_prune_candidate(PlannerInfo *root)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+	List   *result;
+
+	candidate = llast(root->join_partition_prune_candidates);
+	root->join_partition_prune_candidates =
+		list_delete_last(root->join_partition_prune_candidates);
+
+	if (candidate == NULL)
+		return NIL;
+
+	result = candidate->joinpartprune_info_list;
+
+	pfree(candidate);
+
+	return result;
+}
+
 /*
  * add_part_relids
  *		Add new info to a list of Bitmapsets of partitioned relids.
@@ -428,6 +620,8 @@ add_part_relids(List *allpartrelids, Bitmapset *partrelids)
  * partrelids: Set of RT indexes identifying relevant partitioned tables
  *   within a single partitioning hierarchy
  * relid_subplan_map[]: maps child relation relids to subplan indexes
+ * available_rels: the relid set of rels whose Vars may be used for
+ *   pruning.
  * matchedsubplans: on success, receives the set of subplan indexes which
  *   were matched to this partition hierarchy
  *
@@ -440,6 +634,7 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 							  List *prunequal,
 							  Bitmapset *partrelids,
 							  int *relid_subplan_map,
+							  Bitmapset *available_rels,
 							  Bitmapset **matchedsubplans)
 {
 	RelOptInfo *targetpart = NULL;
@@ -539,8 +734,8 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 		 * pruning steps and detects whether there's any possibly-useful quals
 		 * that would require per-scan pruning.
 		 */
-		gen_partprune_steps(subpart, partprunequal, PARTTARGET_INITIAL,
-							&context);
+		gen_partprune_steps(subpart, partprunequal, available_rels,
+							PARTTARGET_INITIAL, &context);
 
 		if (context.contradictory)
 		{
@@ -567,14 +762,15 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			initial_pruning_steps = NIL;
 
 		/*
-		 * If no exec Params appear in potentially-usable pruning clauses,
-		 * then there's no point in even thinking about per-scan pruning.
+		 * If no exec Params or available Vars appear in potentially-usable
+		 * pruning clauses, then there's no point in even thinking about
+		 * per-scan pruning.
 		 */
-		if (context.has_exec_param)
+		if (context.has_exec_param || context.has_vars)
 		{
 			/* ... OK, we'd better think about it */
-			gen_partprune_steps(subpart, partprunequal, PARTTARGET_EXEC,
-								&context);
+			gen_partprune_steps(subpart, partprunequal, available_rels,
+								PARTTARGET_EXEC, &context);
 
 			if (context.contradictory)
 			{
@@ -587,11 +783,14 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			/*
 			 * Detect which exec Params actually got used; the fact that some
 			 * were in available clauses doesn't mean we actually used them.
-			 * Skip per-scan pruning if there are none.
 			 */
 			execparamids = get_partkey_exec_paramids(exec_pruning_steps);
 
-			if (bms_is_empty(execparamids))
+			/*
+			 * Skip per-scan pruning if there are none used exec Params and
+			 * there are none available Vars.
+			 */
+			if (bms_is_empty(execparamids) && !context.has_vars)
 				exec_pruning_steps = NIL;
 		}
 		else
@@ -703,6 +902,9 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  *		Process 'clauses' (typically a rel's baserestrictinfo list of clauses)
  *		and create a list of "partition pruning steps".
  *
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
+ *
  * 'target' tells whether to generate pruning steps for planning (use
  * immutable clauses only), or for executor startup (use any allowable
  * clause except ones containing PARAM_EXEC Params), or for executor
@@ -712,12 +914,13 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  * some subsidiary flags; see the GeneratePruningStepsContext typedef.
  */
 static void
-gen_partprune_steps(RelOptInfo *rel, List *clauses, PartClauseTarget target,
-					GeneratePruningStepsContext *context)
+gen_partprune_steps(RelOptInfo *rel, List *clauses, Bitmapset *available_rels,
+					PartClauseTarget target, GeneratePruningStepsContext *context)
 {
 	/* Initialize all output values to zero/false/NULL */
 	memset(context, 0, sizeof(GeneratePruningStepsContext));
 	context->rel = rel;
+	context->available_rels = available_rels;
 	context->target = target;
 
 	/*
@@ -773,7 +976,7 @@ prune_append_rel_partitions(RelOptInfo *rel)
 	 * If the clauses are found to be contradictory, we can return the empty
 	 * set.
 	 */
-	gen_partprune_steps(rel, clauses, PARTTARGET_PLANNER,
+	gen_partprune_steps(rel, clauses, NULL, PARTTARGET_PLANNER,
 						&gcontext);
 	if (gcontext.contradictory)
 		return NULL;
@@ -1957,9 +2160,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) expr))
+			if (contain_forbidden_var_clause((Node *) expr, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -2155,9 +2359,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) rightop))
+			if (contain_forbidden_var_clause((Node *) rightop, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -3727,3 +3932,54 @@ partkey_datum_from_expr(PartitionPruneContext *context,
 		*value = ExecEvalExprSwitchContext(exprstate, ectx, isnull);
 	}
 }
+
+/*
+ * contain_forbidden_var_clause
+ *	  Recursively scan a clause to discover whether it contains any Var nodes
+ *	  (of the current query level) that do not belong to relations in
+ *	  context->available_rels.
+ *
+ *	  Returns true if any such varnode found.
+ *
+ * Does not examine subqueries, therefore must only be used after reduction
+ * of sublinks to subplans!
+ */
+static bool
+contain_forbidden_var_clause(Node *node, GeneratePruningStepsContext *context)
+{
+	return contain_forbidden_var_clause_walker(node, context);
+}
+
+static bool
+contain_forbidden_var_clause_walker(Node *node, GeneratePruningStepsContext *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		*var = (Var *) node;
+
+		if (var->varlevelsup != 0)
+			return false;
+
+		if (!bms_is_member(var->varno, context->available_rels))
+			return true;		/* abort the tree traversal and return true */
+
+		context->has_vars = true;
+
+		if (context->target != PARTTARGET_EXEC)
+			return true;		/* abort the tree traversal and return true */
+
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+		return true;
+	if (IsA(node, PlaceHolderVar))
+	{
+		if (((PlaceHolderVar *) node)->phlevelsup == 0)
+			return true;		/* abort the tree traversal and return true */
+		/* else fall through to check the contained expr */
+	}
+	return expression_tree_walker(node, contain_forbidden_var_clause_walker,
+								  (void *) context);
+}
diff --git a/src/include/executor/execPartition.h b/src/include/executor/execPartition.h
index 15ec869ac8..720bcc1149 100644
--- a/src/include/executor/execPartition.h
+++ b/src/include/executor/execPartition.h
@@ -121,11 +121,26 @@ typedef struct PartitionPruneState
 	PartitionPruningData *partprunedata[FLEXIBLE_ARRAY_MEMBER];
 } PartitionPruneState;
 
+/*
+ * JoinPartitionPruneState - State object required for plan nodes to perform
+ * join partition pruning.
+ */
+typedef struct JoinPartitionPruneState
+{
+	PartitionPruneState *part_prune_state;
+	int			paramid;
+	int			nplans;
+	bool		finished;
+	Bitmapset  *part_prune_result;
+} JoinPartitionPruneState;
+
 extern PartitionPruneState *ExecInitPartitionPruning(PlanState *planstate,
 													 int n_total_subplans,
 													 PartitionPruneInfo *pruneinfo,
 													 Bitmapset **initially_valid_subplans);
+extern List *ExecInitJoinpartpruneList(PlanState *planstate, List *joinpartprune_info_list);
 extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-										   bool initial_prune);
+										   bool initial_prune,
+										   PlanState *planstate);
 
 #endif							/* EXECPARTITION_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 5d7f17dee0..0aeafcabff 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2678,6 +2678,9 @@ typedef struct HashState
 
 	/* Parallel hash state. */
 	struct ParallelHashJoinState *parallel_state;
+
+	/* Infos for join partition pruning. */
+	List *joinpartprune_state_list;
 } HashState;
 
 /* ----------------
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index ed85dc7414..d066b6105c 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,9 @@ struct PlannerInfo
 	/* not-yet-assigned NestLoopParams */
 	List	   *curOuterParams;
 
+	/* a stack of JoinPartitionPruneInfos */
+	List	   *join_partition_prune_candidates;
+
 	/*
 	 * These fields are workspace for setrefs.c.  Each is an array
 	 * corresponding to glob->subplans.  (We could probably teach
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 24d46c76dc..00058a735e 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -276,6 +276,9 @@ typedef struct Append
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } Append;
 
 /* ----------------
@@ -311,6 +314,9 @@ typedef struct MergeAppend
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } MergeAppend;
 
 /* ----------------
@@ -1207,6 +1213,7 @@ typedef struct Hash
 	bool		skewInherit;	/* is outer join rel an inheritance tree? */
 	/* all other info is in the parent HashJoin node */
 	Cardinality rows_total;		/* estimate total rows if parallel_aware */
+	List	   *joinpartprune_info_list;	/* infos for join partition pruning */
 } Hash;
 
 /* ----------------
@@ -1553,6 +1560,35 @@ typedef struct PartitionPruneStepCombine
 	List	   *source_stepids;
 } PartitionPruneStepCombine;
 
+/*
+ * JoinPartitionPruneCandidateInfo - Information required to build
+ * JoinPartitionPruneInfos.
+ */
+typedef struct JoinPartitionPruneCandidateInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	List	   *joinrestrictinfo;
+	Bitmapset  *inner_relids;
+	double		inner_rows;
+	List	   *joinpartprune_info_list;
+} JoinPartitionPruneCandidateInfo;
+
+/*
+ * JoinPartitionPruneInfo - Details required to allow the executor to prune
+ * partitions during join.
+ */
+typedef struct JoinPartitionPruneInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	PartitionPruneInfo *part_prune_info;
+	int			paramid;
+	int			nplans;
+} JoinPartitionPruneInfo;
+
 
 /*
  * Plan invalidation info
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 6d50afbf74..52de844f6d 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -211,5 +211,9 @@ extern void set_foreign_size_estimates(PlannerInfo *root, RelOptInfo *rel);
 extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *target);
 extern double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 								   Path *bitmapqual, int loop_count, Cost *cost, double *tuple);
+extern double compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+									 Cost append_total_cost, int append_nplans,
+									 Relids inner_relids, double inner_rows,
+									 List *prunequal);
 
 #endif							/* COST_H */
diff --git a/src/include/partitioning/partprune.h b/src/include/partitioning/partprune.h
index 8636e04e37..899aa61b34 100644
--- a/src/include/partitioning/partprune.h
+++ b/src/include/partitioning/partprune.h
@@ -19,6 +19,8 @@
 
 struct PlannerInfo;				/* avoid including pathnodes.h here */
 struct RelOptInfo;
+struct Path;
+struct JoinPath;
 
 
 /*
@@ -73,7 +75,15 @@ typedef struct PartitionPruneContext
 extern PartitionPruneInfo *make_partition_pruneinfo(struct PlannerInfo *root,
 													struct RelOptInfo *parentrel,
 													List *subpaths,
-													List *prunequal);
+													List *prunequal,
+													Bitmapset *available_rels);
+extern Bitmapset *make_join_partition_pruneinfos(struct PlannerInfo *root,
+												 struct RelOptInfo *parentrel,
+												 struct Path *best_path,
+												 List *subpaths);
+extern void prepare_join_partition_prune_candidate(struct PlannerInfo *root,
+												   struct JoinPath *jpath);
+extern List *get_join_partition_prune_candidate(struct PlannerInfo *root);
 extern Bitmapset *prune_append_rel_partitions(struct RelOptInfo *rel);
 extern Bitmapset *get_matching_partitions(PartitionPruneContext *context,
 										  List *pruning_steps);
diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 9a4c48c055..a08e7a1f0a 100644
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3003,6 +3003,92 @@ order by tbl1.col1, tprt.col1;
 ------+------
 (0 rows)
 
+-- join partition pruning
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+                         explain_join_partition_pruning                         
+--------------------------------------------------------------------------------
+ Hash Right Join (actual rows=2 loops=1)
+   Output: p1.col1, p2.col1, t.col1
+   Hash Cond: ((p1.col1 = t.col1) AND (p2.col1 = t.col1))
+   ->  Hash Join (actual rows=3 loops=1)
+         Output: p1.col1, p2.col1
+         Hash Cond: (p1.col1 = p2.col1)
+         ->  Append (actual rows=3 loops=1)
+               Join Partition Pruning: $0
+               ->  Seq Scan on public.tprt_1 p1_1 (never executed)
+                     Output: p1_1.col1
+               ->  Seq Scan on public.tprt_2 p1_2 (actual rows=3 loops=1)
+                     Output: p1_2.col1
+               ->  Seq Scan on public.tprt_3 p1_3 (never executed)
+                     Output: p1_3.col1
+               ->  Seq Scan on public.tprt_4 p1_4 (never executed)
+                     Output: p1_4.col1
+               ->  Seq Scan on public.tprt_5 p1_5 (never executed)
+                     Output: p1_5.col1
+               ->  Seq Scan on public.tprt_6 p1_6 (never executed)
+                     Output: p1_6.col1
+         ->  Hash (actual rows=3 loops=1)
+               Output: p2.col1
+               Buckets: 1024  Batches: 1  Memory Usage: NkB
+               ->  Append (actual rows=3 loops=1)
+                     Join Partition Pruning: $1
+                     ->  Seq Scan on public.tprt_1 p2_1 (never executed)
+                           Output: p2_1.col1
+                     ->  Seq Scan on public.tprt_2 p2_2 (actual rows=3 loops=1)
+                           Output: p2_2.col1
+                     ->  Seq Scan on public.tprt_3 p2_3 (never executed)
+                           Output: p2_3.col1
+                     ->  Seq Scan on public.tprt_4 p2_4 (never executed)
+                           Output: p2_4.col1
+                     ->  Seq Scan on public.tprt_5 p2_5 (never executed)
+                           Output: p2_5.col1
+                     ->  Seq Scan on public.tprt_6 p2_6 (never executed)
+                           Output: p2_6.col1
+   ->  Hash (actual rows=2 loops=1)
+         Output: t.col1
+         Buckets: 1024  Batches: 1  Memory Usage: NkB
+         Partition Prune: $0, $1
+         ->  Seq Scan on public.tbl1 t (actual rows=2 loops=1)
+               Output: t.col1
+(43 rows)
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+ col1 | col1 | col1 
+------+------+------
+  501 |  501 |  501
+  505 |  505 |  505
+(2 rows)
+
 drop table tbl1, tprt;
 -- Test with columns defined in varying orders between each level
 create table part_abc (a int not null, b int not null, c int not null) partition by list (a);
diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index 7bf3920827..fc5982edcf 100644
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -727,6 +727,45 @@ select tbl1.col1, tprt.col1 from tbl1
 inner join tprt on tbl1.col1 = tprt.col1
 order by tbl1.col1, tprt.col1;
 
+-- join partition pruning
+
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+
 drop table tbl1, tprt;
 
 -- Test with columns defined in varying orders between each level
-- 
2.31.0

From 05d18d47135ba086fe416c02abdaa44b69612c03 Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Mon, 14 Aug 2023 14:55:26 +0800
Subject: [PATCH v6] Support run-time partition pruning for hash join

If we have a hash join with an Append node on the outer side, something
like

 Hash Join
   Hash Cond: (pt.a = t.a)
   ->  Append
         ->  Seq Scan on pt_p1 pt_1
         ->  Seq Scan on pt_p2 pt_2
         ->  Seq Scan on pt_p3 pt_3
   ->  Hash
         ->  Seq Scan on t

We can actually prune those subnodes of the Append that cannot possibly
contain any matching tuples from the other side of the join.  To do
that, when building the Hash table, for each row from the inner side we
can compute the minimum set of subnodes that can possibly match the join
condition.  When we have built the Hash table and start to execute the
Append node, we should have known which subnodes are survived and thus
can skip other subnodes.

This patch implements this idea.
---
 src/backend/commands/explain.c                |  61 ++++
 src/backend/executor/execPartition.c          | 127 +++++++-
 src/backend/executor/nodeAppend.c             |  32 +-
 src/backend/executor/nodeHash.c               |  75 +++++
 src/backend/executor/nodeHashjoin.c           |  10 +
 src/backend/executor/nodeMergeAppend.c        |  22 +-
 src/backend/optimizer/path/costsize.c         | 106 +++++++
 src/backend/optimizer/plan/createplan.c       |  49 ++-
 src/backend/optimizer/plan/setrefs.c          |  61 ++++
 src/backend/partitioning/partprune.c          | 298 ++++++++++++++++--
 src/include/executor/execPartition.h          |  17 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/pathnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |  36 +++
 src/include/optimizer/cost.h                  |   4 +
 src/include/partitioning/partprune.h          |  12 +-
 src/test/regress/expected/partition_prune.out |  86 +++++
 src/test/regress/sql/partition_prune.sql      |  39 +++
 18 files changed, 992 insertions(+), 49 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 83d00a4663..04450b9c37 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -18,6 +18,7 @@
 #include "commands/createas.h"
 #include "commands/defrem.h"
 #include "commands/prepare.h"
+#include "executor/execPartition.h"
 #include "executor/nodeHash.h"
 #include "foreign/fdwapi.h"
 #include "jit/jit.h"
@@ -118,6 +119,9 @@ static void show_instrumentation_count(const char *qlabel, int which,
 									   PlanState *planstate, ExplainState *es);
 static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
 static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
+static void show_join_pruning_result_info(Bitmapset *join_prune_paramids,
+										  ExplainState *es);
+static void show_joinpartprune_info(HashState *hashstate, ExplainState *es);
 static const char *explain_get_index_name(Oid indexId);
 static bool peek_buffer_usage(ExplainState *es, const BufferUsage *usage);
 static void show_buffer_usage(ExplainState *es, const BufferUsage *usage);
@@ -2104,9 +2108,17 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			show_incremental_sort_info(castNode(IncrementalSortState, planstate),
 									   es);
 			break;
+		case T_Append:
+			if (es->verbose)
+				show_join_pruning_result_info(((Append *) plan)->join_prune_paramids,
+											  es);
+			break;
 		case T_MergeAppend:
 			show_merge_append_keys(castNode(MergeAppendState, planstate),
 								   ancestors, es);
+			if (es->verbose)
+				show_join_pruning_result_info(((MergeAppend *) plan)->join_prune_paramids,
+											  es);
 			break;
 		case T_Result:
 			show_upper_qual((List *) ((Result *) plan)->resconstantqual,
@@ -2122,6 +2134,8 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			break;
 		case T_Hash:
 			show_hash_info(castNode(HashState, planstate), es);
+			if (es->verbose)
+				show_joinpartprune_info(castNode(HashState, planstate), es);
 			break;
 		case T_Memoize:
 			show_memoize_info(castNode(MemoizeState, planstate), ancestors,
@@ -3562,6 +3576,53 @@ show_eval_params(Bitmapset *bms_params, ExplainState *es)
 		ExplainPropertyList("Params Evaluated", params, es);
 }
 
+/*
+ * Show join partition pruning results at Append/MergeAppend nodes.
+ */
+static void
+show_join_pruning_result_info(Bitmapset *join_prune_paramids, ExplainState *es)
+{
+	int			paramid = -1;
+	List	   *params = NIL;
+
+	if (bms_is_empty(join_prune_paramids))
+		return;
+
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Join Partition Pruning", params, es);
+}
+
+/*
+ * Show join partition pruning infos at Hash nodes.
+ */
+static void
+show_joinpartprune_info(HashState *hashstate, ExplainState *es)
+{
+	List	   *params = NIL;
+	ListCell   *lc;
+
+	if (!hashstate->joinpartprune_state_list)
+		return;
+
+	foreach(lc, hashstate->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", jpstate->paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Partition Prune", params, es);
+}
+
 /*
  * Fetch the name of an index in an EXPLAIN
  *
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index b22040ae8e..95c791633c 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -199,6 +199,8 @@ static void find_matching_subplans_recurse(PartitionPruningData *prunedata,
 										   PartitionedRelPruningData *pprune,
 										   bool initial_prune,
 										   Bitmapset **validsubplans);
+static bool get_join_prune_matching_subplans(PlanState *planstate,
+											 Bitmapset **partset);
 
 
 /*
@@ -1806,7 +1808,7 @@ ExecInitPartitionPruning(PlanState *planstate,
 	 * Perform an initial partition prune pass, if required.
 	 */
 	if (prunestate->do_initial_prune)
-		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true);
+		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true, NULL);
 	else
 	{
 		/* No pruning, so we'll need to initialize all subplans */
@@ -1836,6 +1838,37 @@ ExecInitPartitionPruning(PlanState *planstate,
 	return prunestate;
 }
 
+/*
+ * ExecInitJoinpartpruneList
+ *		Initialize data structures needed for join partition pruning
+ */
+List *
+ExecInitJoinpartpruneList(PlanState *planstate,
+						  List *joinpartprune_info_list)
+{
+	ListCell   *lc;
+	List	   *result = NIL;
+
+	foreach(lc, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(lc);
+		JoinPartitionPruneState *jpstate = palloc(sizeof(JoinPartitionPruneState));
+
+		jpstate->part_prune_state =
+			CreatePartitionPruneState(planstate, jpinfo->part_prune_info);
+		Assert(jpstate->part_prune_state->do_exec_prune);
+
+		jpstate->paramid = jpinfo->paramid;
+		jpstate->nplans = jpinfo->nplans;
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+
+		result = lappend(result, jpstate);
+	}
+
+	return result;
+}
+
 /*
  * CreatePartitionPruneState
  *		Build the data structure required for calling ExecFindMatchingSubPlans
@@ -2273,7 +2306,9 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
 /*
  * ExecFindMatchingSubPlans
  *		Determine which subplans match the pruning steps detailed in
- *		'prunestate' for the current comparison expression values.
+ *		'prunestate' if any for the current comparison expression values, and
+ *		meanwhile match the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.
  *
  * Pass initial_prune if PARAM_EXEC Params cannot yet be evaluated.  This
  * differentiates the initial executor-time pruning step from later
@@ -2281,11 +2316,30 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
  */
 Bitmapset *
 ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-						 bool initial_prune)
+						 bool initial_prune,
+						 PlanState *planstate)
 {
 	Bitmapset  *result = NULL;
 	MemoryContext oldcontext;
 	int			i;
+	Bitmapset  *join_prune_partset = NULL;
+	bool		do_join_prune;
+
+	/* Retrieve the join partition pruning results if any */
+	do_join_prune =
+		get_join_prune_matching_subplans(planstate, &join_prune_partset);
+
+	/*
+	 * Either we're here on partition prune done according to the pruning steps
+	 * detailed in 'prunestate', or we have done join partition prune.
+	 */
+	Assert(do_join_prune || prunestate != NULL);
+
+	/*
+	 * If there is no 'prunestate', then rely entirely on join pruning.
+	 */
+	if (prunestate == NULL)
+		return join_prune_partset;
 
 	/*
 	 * Either we're here on the initial prune done during pruning
@@ -2326,6 +2380,10 @@ ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
 	/* Add in any subplans that partition pruning didn't account for */
 	result = bms_add_members(result, prunestate->other_subplans);
 
+	/* Intersect join partition pruning results */
+	if (do_join_prune)
+		result = bms_intersect(result, join_prune_partset);
+
 	MemoryContextSwitchTo(oldcontext);
 
 	/* Copy result out of the temp context before we reset it */
@@ -2396,3 +2454,66 @@ find_matching_subplans_recurse(PartitionPruningData *prunedata,
 		}
 	}
 }
+
+/*
+ * get_join_prune_matching_subplans
+ *		Retrieve the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.  Return true if we can
+ *		do join partition pruning, otherwise return false.
+ *
+ * Adds valid (non-prunable) subplan IDs to *partset
+ */
+static bool
+get_join_prune_matching_subplans(PlanState *planstate, Bitmapset **partset)
+{
+	Bitmapset  *join_prune_paramids;
+	int			nplans;
+	int			paramid;
+
+	if (planstate == NULL)
+		return false;
+
+	if (IsA(planstate, AppendState))
+	{
+		join_prune_paramids =
+			((Append *) planstate->plan)->join_prune_paramids;
+		nplans = ((AppendState *) planstate)->as_nplans;
+	}
+	else if (IsA(planstate, MergeAppendState))
+	{
+		join_prune_paramids =
+			((MergeAppend *) planstate->plan)->join_prune_paramids;
+		nplans = ((MergeAppendState *) planstate)->ms_nplans;
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(planstate));
+		return false;
+	}
+
+	if (bms_is_empty(join_prune_paramids))
+		return false;
+
+	Assert(nplans > 0);
+	*partset = bms_add_range(NULL, 0, nplans - 1);
+
+	paramid = -1;
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		ParamExecData *param;
+		JoinPartitionPruneState *jpstate;
+
+		param = &(planstate->state->es_param_exec_vals[paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		jpstate = (JoinPartitionPruneState *) DatumGetPointer(param->value);
+
+		if (jpstate != NULL)
+			*partset = bms_intersect(*partset, jpstate->part_prune_result);
+		else	/* the Hash node for this pruning has not been executed */
+			elog(WARNING, "Join partition pruning $%d has not been performed yet.",
+				 paramid);
+	}
+
+	return true;
+}
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index c7059e7528..b68a1e2eb2 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -151,11 +151,13 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill as_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill as_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 		{
 			appendstate->as_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 			appendstate->as_valid_subplans_identified = true;
@@ -170,10 +172,18 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		appendstate->as_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
-		appendstate->as_valid_subplans_identified = true;
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		appendstate->as_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill as_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+		{
+			appendstate->as_valid_subplans = validsubplans;
+			appendstate->as_valid_subplans_identified = true;
+		}
 	}
 
 	/*
@@ -580,7 +590,7 @@ choose_next_subplan_locally(AppendState *node)
 		else if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 		}
 
@@ -647,7 +657,7 @@ choose_next_subplan_for_leader(AppendState *node)
 		if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 
 			/*
@@ -723,7 +733,7 @@ choose_next_subplan_for_worker(AppendState *node)
 	else if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		mark_invalid_subplans_as_finished(node);
@@ -876,7 +886,7 @@ ExecAppendAsyncBegin(AppendState *node)
 	if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		classify_matching_subplans(node);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index f90e16ede8..00138a61a2 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -31,6 +31,7 @@
 #include "catalog/pg_statistic.h"
 #include "commands/tablespace.h"
 #include "executor/execdebug.h"
+#include "executor/execPartition.h"
 #include "executor/hashjoin.h"
 #include "executor/nodeHash.h"
 #include "executor/nodeHashjoin.h"
@@ -48,6 +49,8 @@ static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable);
+static void ExecJoinPartitionPrune(HashState *node);
+static void ExecStoreJoinPartitionPruneResult(HashState *node);
 static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node,
 								  int mcvsToUse);
 static void ExecHashSkewTableInsert(HashJoinTable hashtable,
@@ -189,8 +192,14 @@ MultiExecPrivateHash(HashState *node)
 			}
 			hashtable->totalTuples += 1;
 		}
+
+		/* Perform join partition pruning */
+		ExecJoinPartitionPrune(node);
 	}
 
+	/* Store the surviving partitions for Append/MergeAppend nodes */
+	ExecStoreJoinPartitionPruneResult(node);
+
 	/* resize the hash table if needed (NTUP_PER_BUCKET exceeded) */
 	if (hashtable->nbuckets != hashtable->nbuckets_optimal)
 		ExecHashIncreaseNumBuckets(hashtable);
@@ -401,6 +410,12 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	hashstate->hashkeys =
 		ExecInitExprList(node->hashkeys, (PlanState *) hashstate);
 
+	/*
+	 * initialize join partition pruning infos
+	 */
+	hashstate->joinpartprune_state_list =
+		ExecInitJoinpartpruneList(&hashstate->ps, node->joinpartprune_info_list);
+
 	return hashstate;
 }
 
@@ -1610,6 +1625,56 @@ ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable)
 	}
 }
 
+/*
+ * ExecJoinPartitionPrune
+ *		Perform join partition pruning at this join for each
+ *		JoinPartitionPruneState.
+ */
+static void
+ExecJoinPartitionPrune(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		Bitmapset	   *matching_subPlans;
+
+		if (jpstate->finished)
+			continue;
+
+		matching_subPlans =
+			ExecFindMatchingSubPlans(jpstate->part_prune_state, false, NULL);
+		jpstate->part_prune_result =
+			bms_add_members(jpstate->part_prune_result, matching_subPlans);
+
+		if (bms_num_members(jpstate->part_prune_result) == jpstate->nplans)
+			jpstate->finished = true;
+	}
+}
+
+/*
+ * ExecStoreJoinPartitionPruneResult
+ *		For each JoinPartitionPruneState, store the set of surviving partitions
+ *		to make it available for the Append/MergeAppend node.
+ */
+static void
+ExecStoreJoinPartitionPruneResult(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		ParamExecData	   *param;
+
+		param = &(node->ps.state->es_param_exec_vals[jpstate->paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		param->value = PointerGetDatum(jpstate);
+	}
+}
+
 /*
  * ExecHashTableInsert
  *		insert a tuple into the hash table depending on the hash value
@@ -2354,6 +2419,16 @@ void
 ExecReScanHash(HashState *node)
 {
 	PlanState  *outerPlan = outerPlanState(node);
+	ListCell   *lc;
+
+	/* reset the state in JoinPartitionPruneStates */
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+	}
 
 	/*
 	 * if chgParam of subnode is not null then plan will be re-scanned by
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 1cbec4647c..4f84799929 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -311,6 +311,16 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 					 */
 					node->hj_FirstOuterTupleSlot = NULL;
 				}
+				else if (hashNode->joinpartprune_state_list != NIL)
+				{
+					/*
+					 * Give the hash node a chance to run join partition
+					 * pruning if there is any JoinPartitionPruneState that can
+					 * be evaluated at it.  So do not apply the empty-outer
+					 * optimization in this case.
+					 */
+					node->hj_FirstOuterTupleSlot = NULL;
+				}
 				else if (HJ_FILL_OUTER(node) ||
 						 (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
 						  !node->hj_OuterNotEmpty))
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 0817868452..ec0ac29654 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -99,11 +99,13 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill ms_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill ms_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 			mergestate->ms_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 	}
 	else
@@ -115,9 +117,15 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		mergestate->ms_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		mergestate->ms_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill ms_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+			mergestate->ms_valid_subplans = validsubplans;
 	}
 
 	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
@@ -218,7 +226,7 @@ ExecMergeAppend(PlanState *pstate)
 		 */
 		if (node->ms_valid_subplans == NULL)
 			node->ms_valid_subplans =
-				ExecFindMatchingSubPlans(node->ms_prune_state, false);
+				ExecFindMatchingSubPlans(node->ms_prune_state, false, &node->ps);
 
 		/*
 		 * First time through: pull the first tuple from each valid subplan,
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 8b76e98529..ea3d5e57c1 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -173,6 +173,10 @@ static void get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
 static bool has_indexed_join_quals(NestPath *path);
 static double approx_tuple_count(PlannerInfo *root, JoinPath *path,
 								 List *quals);
+static double get_joinrel_matching_outer_size(PlannerInfo *root,
+											  RelOptInfo *outer_rel,
+											  Relids inner_relids,
+											  List *restrictlist);
 static double calc_joinrel_size_estimate(PlannerInfo *root,
 										 RelOptInfo *joinrel,
 										 RelOptInfo *outer_rel,
@@ -5409,6 +5413,61 @@ get_parameterized_joinrel_size(PlannerInfo *root, RelOptInfo *rel,
 	return nrows;
 }
 
+/*
+ * get_joinrel_matching_outer_size
+ *		Make a size estimate for the outer side that matches the inner side.
+ */
+static double
+get_joinrel_matching_outer_size(PlannerInfo *root,
+								RelOptInfo *outer_rel,
+								Relids inner_relids,
+								List *restrictlist)
+{
+	double		nrows;
+	Selectivity fkselec;
+	Selectivity jselec;
+	SpecialJoinInfo *sjinfo;
+	SpecialJoinInfo sjinfo_data;
+
+	sjinfo = &sjinfo_data;
+	sjinfo->type = T_SpecialJoinInfo;
+	sjinfo->min_lefthand = outer_rel->relids;
+	sjinfo->min_righthand = inner_relids;
+	sjinfo->syn_lefthand = outer_rel->relids;
+	sjinfo->syn_righthand = inner_relids;
+	sjinfo->jointype = JOIN_SEMI;
+	sjinfo->ojrelid = 0;
+	sjinfo->commute_above_l = NULL;
+	sjinfo->commute_above_r = NULL;
+	sjinfo->commute_below_l = NULL;
+	sjinfo->commute_below_r = NULL;
+	/* we don't bother trying to make the remaining fields valid */
+	sjinfo->lhs_strict = false;
+	sjinfo->semi_can_btree = false;
+	sjinfo->semi_can_hash = false;
+	sjinfo->semi_operators = NIL;
+	sjinfo->semi_rhs_exprs = NIL;
+
+	fkselec = get_foreign_key_join_selectivity(root,
+											   outer_rel->relids,
+											   inner_relids,
+											   sjinfo,
+											   &restrictlist);
+	jselec = clauselist_selectivity(root,
+									restrictlist,
+									0,
+									sjinfo->jointype,
+									sjinfo);
+
+	nrows = outer_rel->rows * fkselec * jselec;
+	nrows = clamp_row_est(nrows);
+
+	/* For safety, make sure result is not more than the base estimate */
+	if (nrows > outer_rel->rows)
+		nrows = outer_rel->rows;
+	return nrows;
+}
+
 /*
  * calc_joinrel_size_estimate
  *		Workhorse for set_joinrel_size_estimates and
@@ -6530,3 +6589,50 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 
 	return pages_fetched;
 }
+
+/*
+ * compute_partprune_cost
+ *		Compute the overhead of join partition pruning.
+ */
+double
+compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+					   Cost append_total_cost, int append_nplans,
+					   Relids inner_relids, double inner_rows,
+					   List *prunequal)
+{
+	Cost		prune_cost;
+	Cost		saved_cost;
+	double		matching_outer_rows;
+	double		unmatched_nplans;
+
+	switch (appendrel->part_scheme->strategy)
+	{
+
+		case PARTITION_STRATEGY_LIST:
+		case PARTITION_STRATEGY_RANGE:
+			prune_cost = cpu_operator_cost * LOG2(append_nplans) * inner_rows;
+			break;
+		case PARTITION_STRATEGY_HASH:
+			prune_cost = cpu_operator_cost * append_nplans * inner_rows;
+			break;
+		default:
+			elog(ERROR, "unexpected partition strategy: %d",
+				 (int) appendrel->part_scheme->strategy);
+			break;
+	}
+
+	matching_outer_rows =
+		get_joinrel_matching_outer_size(root,
+										appendrel,
+										inner_relids,
+										prunequal);
+
+	/*
+	 * We assume that each outer joined row occupies one new partition.  This
+	 * is really the worst case.
+	 */
+	unmatched_nplans = append_nplans - Min(matching_outer_rows, append_nplans);
+	saved_cost = (unmatched_nplans / append_nplans) * append_total_cost;
+
+	return prune_cost - saved_cost;
+}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 610f4a56d6..55cd3bb616 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -242,7 +242,8 @@ static Hash *make_hash(Plan *lefttree,
 					   List *hashkeys,
 					   Oid skewTable,
 					   AttrNumber skewColumn,
-					   bool skewInherit);
+					   bool skewInherit,
+					   List *joinpartprune_info_list);
 static MergeJoin *make_mergejoin(List *tlist,
 								 List *joinclauses, List *otherclauses,
 								 List *mergeclauses,
@@ -342,6 +343,7 @@ create_plan(PlannerInfo *root, Path *best_path)
 	/* Initialize this module's workspace in PlannerInfo */
 	root->curOuterRels = NULL;
 	root->curOuterParams = NIL;
+	root->join_partition_prune_candidates = NIL;
 
 	/* Recursively process the path tree, demanding the correct tlist result */
 	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
@@ -369,6 +371,8 @@ create_plan(PlannerInfo *root, Path *best_path)
 	if (root->curOuterParams != NIL)
 		elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
 
+	Assert(root->join_partition_prune_candidates == NIL);
+
 	/*
 	 * Reset plan_params to ensure param IDs used for nestloop params are not
 	 * re-used later
@@ -1223,6 +1227,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	int			nasyncplans = 0;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 	int			nodenumsortkeys = 0;
 	AttrNumber *nodeSortColIdx = NULL;
 	Oid		   *nodeSortOperators = NULL;
@@ -1377,6 +1382,8 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1399,13 +1406,20 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 			partpruneinfo =
 				make_partition_pruneinfo(root, rel,
 										 best_path->subpaths,
-										 prunequal);
+										 prunequal,
+										 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	plan->appendplans = subplans;
 	plan->nasyncplans = nasyncplans;
 	plan->first_partial_plan = best_path->first_partial_path;
 	plan->part_prune_info = partpruneinfo;
+	plan->join_prune_paramids = join_prune_paramids;
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -1445,6 +1459,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	ListCell   *subpaths;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 
 	/*
 	 * We don't have the actual creation of the MergeAppend node split out
@@ -1541,6 +1556,8 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1554,11 +1571,18 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		if (prunequal != NIL)
 			partpruneinfo = make_partition_pruneinfo(root, rel,
 													 best_path->subpaths,
-													 prunequal);
+													 prunequal,
+													 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	node->mergeplans = subplans;
 	node->part_prune_info = partpruneinfo;
+	node->join_prune_paramids = join_prune_paramids;
 
 	/*
 	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
@@ -4743,6 +4767,13 @@ create_hashjoin_plan(PlannerInfo *root,
 	AttrNumber	skewColumn = InvalidAttrNumber;
 	bool		skewInherit = false;
 	ListCell   *lc;
+	List	   *joinpartprune_info_list;
+
+	/*
+	 * Collect information required to build JoinPartitionPruneInfos at this
+	 * join.
+	 */
+	prepare_join_partition_prune_candidate(root, &best_path->jpath);
 
 	/*
 	 * HashJoin can project, so we don't have to demand exact tlists from the
@@ -4754,6 +4785,11 @@ create_hashjoin_plan(PlannerInfo *root,
 	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
 									 (best_path->num_batches > 1) ? CP_SMALL_TLIST : 0);
 
+	/*
+	 * Retrieve all the JoinPartitionPruneInfos for this join.
+	 */
+	joinpartprune_info_list = get_join_partition_prune_candidate(root);
+
 	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
 									 CP_SMALL_TLIST);
 
@@ -4859,7 +4895,8 @@ create_hashjoin_plan(PlannerInfo *root,
 						  inner_hashkeys,
 						  skewTable,
 						  skewColumn,
-						  skewInherit);
+						  skewInherit,
+						  joinpartprune_info_list);
 
 	/*
 	 * Set Hash node's startup & total costs equal to total cost of input
@@ -5986,7 +6023,8 @@ make_hash(Plan *lefttree,
 		  List *hashkeys,
 		  Oid skewTable,
 		  AttrNumber skewColumn,
-		  bool skewInherit)
+		  bool skewInherit,
+		  List *joinpartprune_info_list)
 {
 	Hash	   *node = makeNode(Hash);
 	Plan	   *plan = &node->plan;
@@ -6000,6 +6038,7 @@ make_hash(Plan *lefttree,
 	node->skewTable = skewTable;
 	node->skewColumn = skewColumn;
 	node->skewInherit = skewInherit;
+	node->joinpartprune_info_list = joinpartprune_info_list;
 
 	return node;
 }
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 22a1fa29f3..c83d3bc0ad 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -156,6 +156,11 @@ static Plan *set_mergeappend_references(PlannerInfo *root,
 										MergeAppend *mplan,
 										int rtoffset);
 static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_joinpartitionprune_references(PlannerInfo *root,
+											  List *joinpartprune_info_list,
+											  indexed_tlist *outer_itlist,
+											  int rtoffset,
+											  double num_exec);
 static Relids offset_relid_set(Relids relids, int rtoffset);
 static Node *fix_scan_expr(PlannerInfo *root, Node *node,
 						   int rtoffset, double num_exec);
@@ -1897,6 +1902,62 @@ set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset)
 
 	/* Hash nodes don't have their own quals */
 	Assert(plan->qual == NIL);
+
+	set_joinpartitionprune_references(root,
+									  hplan->joinpartprune_info_list,
+									  outer_itlist,
+									  rtoffset,
+									  NUM_EXEC_TLIST(plan));
+}
+
+/*
+ * set_joinpartitionprune_references
+ *	   Do set_plan_references processing on JoinPartitionPruneInfos
+ */
+static void
+set_joinpartitionprune_references(PlannerInfo *root,
+								  List *joinpartprune_info_list,
+								  indexed_tlist *outer_itlist,
+								  int rtoffset,
+								  double num_exec)
+{
+	ListCell   *l;
+
+	foreach(l, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(l);
+		ListCell   *l1;
+
+		foreach(l1, jpinfo->part_prune_info->prune_infos)
+		{
+			List	   *prune_infos = lfirst(l1);
+			ListCell   *l2;
+
+			foreach(l2, prune_infos)
+			{
+				PartitionedRelPruneInfo *pinfo = lfirst(l2);
+
+				pinfo->rtindex += rtoffset;
+
+				pinfo->initial_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->initial_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+				pinfo->exec_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->exec_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+			}
+		}
+	}
 }
 
 /*
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 6b635e8ad1..17725aa972 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -48,7 +48,9 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/cost.h"
 #include "optimizer/optimizer.h"
+#include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/restrictinfo.h"
 #include "parser/parsetree.h"
 #include "partitioning/partbounds.h"
 #include "partitioning/partprune.h"
@@ -103,15 +105,16 @@ typedef enum PartClauseTarget
  *
  * gen_partprune_steps() initializes and returns an instance of this struct.
  *
- * Note that has_mutable_op, has_mutable_arg, and has_exec_param are set if
- * we found any potentially-useful-for-pruning clause having those properties,
- * whether or not we actually used the clause in the steps list.  This
- * definition allows us to skip the PARTTARGET_EXEC pass in some cases.
+ * Note that has_mutable_op, has_mutable_arg, has_exec_param and has_vars are
+ * set if we found any potentially-useful-for-pruning clause having those
+ * properties, whether or not we actually used the clause in the steps list.
+ * This definition allows us to skip the PARTTARGET_EXEC pass in some cases.
  */
 typedef struct GeneratePruningStepsContext
 {
 	/* Copies of input arguments for gen_partprune_steps: */
 	RelOptInfo *rel;			/* the partitioned relation */
+	Bitmapset  *available_rels;	/* rels whose Vars may be used for pruning */
 	PartClauseTarget target;	/* use-case we're generating steps for */
 	/* Result data: */
 	List	   *steps;			/* list of PartitionPruneSteps */
@@ -119,6 +122,7 @@ typedef struct GeneratePruningStepsContext
 	bool		has_mutable_arg;	/* clauses include any mutable comparison
 									 * values, *other than* exec params */
 	bool		has_exec_param; /* clauses include any PARAM_EXEC params */
+	bool		has_vars;		/* clauses include any Vars from 'available_rels' */
 	bool		contradictory;	/* clauses were proven self-contradictory */
 	/* Working state: */
 	int			next_step_id;
@@ -144,8 +148,10 @@ static List *make_partitionedrel_pruneinfo(PlannerInfo *root,
 										   List *prunequal,
 										   Bitmapset *partrelids,
 										   int *relid_subplan_map,
+										   Bitmapset *available_rels,
 										   Bitmapset **matchedsubplans);
 static void gen_partprune_steps(RelOptInfo *rel, List *clauses,
+								Bitmapset *available_rels,
 								PartClauseTarget target,
 								GeneratePruningStepsContext *context);
 static List *gen_partprune_steps_internal(GeneratePruningStepsContext *context,
@@ -204,6 +210,10 @@ static PartClauseMatchStatus match_boolean_partition_clause(Oid partopfamily,
 static void partkey_datum_from_expr(PartitionPruneContext *context,
 									Expr *expr, int stateidx,
 									Datum *value, bool *isnull);
+static bool contain_forbidden_var_clause(Node *node,
+										 GeneratePruningStepsContext *context);
+static bool contain_forbidden_var_clause_walker(Node *node,
+												GeneratePruningStepsContext *context);
 
 
 /*
@@ -216,11 +226,14 @@ static void partkey_datum_from_expr(PartitionPruneContext *context,
  * 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).
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
  */
 PartitionPruneInfo *
 make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 						 List *subpaths,
-						 List *prunequal)
+						 List *prunequal,
+						 Bitmapset *available_rels)
 {
 	PartitionPruneInfo *pruneinfo;
 	Bitmapset  *allmatchedsubplans = NULL;
@@ -313,6 +326,7 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 												  prunequal,
 												  partrelids,
 												  relid_subplan_map,
+												  available_rels,
 												  &matchedsubplans);
 
 		/* When pruning is possible, record the matched subplans */
@@ -360,6 +374,184 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	return pruneinfo;
 }
 
+/*
+ * make_join_partition_pruneinfos
+ *		Builds one JoinPartitionPruneInfo for each join at which join partition
+ *		pruning is possible for this appendrel.
+ *
+ * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
+ * of scan paths for its child rels.
+ */
+Bitmapset *
+make_join_partition_pruneinfos(PlannerInfo *root, RelOptInfo *parentrel,
+							   Path *best_path, List *subpaths)
+{
+	Bitmapset  *result = NULL;
+	ListCell   *lc;
+
+	if (!IS_PARTITIONED_REL(parentrel))
+		return NULL;
+
+	foreach(lc, root->join_partition_prune_candidates)
+	{
+		JoinPartitionPruneCandidateInfo *candidate =
+			(JoinPartitionPruneCandidateInfo *) lfirst(lc);
+		PartitionPruneInfo *part_prune_info;
+		List	   *prunequal;
+		Relids		joinrelids;
+		ListCell   *l;
+		double		prune_cost;
+
+		if (candidate == NULL)
+			continue;
+
+		/*
+		 * Identify all joinclauses that are movable to this appendrel given
+		 * this inner side relids.  Only those clauses can be used for join
+		 * partition pruning.
+		 */
+		joinrelids = bms_union(parentrel->relids, candidate->inner_relids);
+		prunequal = NIL;
+		foreach(l, candidate->joinrestrictinfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+
+			if (join_clause_is_movable_into(rinfo,
+											parentrel->relids,
+											joinrelids))
+				prunequal = lappend(prunequal, rinfo);
+		}
+
+		if (prunequal == NIL)
+			continue;
+
+		/*
+		 * Check the overhead of this pruning
+		 */
+		prune_cost = compute_partprune_cost(root,
+											parentrel,
+											best_path->total_cost,
+											list_length(subpaths),
+											candidate->inner_relids,
+											candidate->inner_rows,
+											prunequal);
+		if (prune_cost > 0)
+			continue;
+
+		part_prune_info = make_partition_pruneinfo(root, parentrel,
+												   subpaths,
+												   prunequal,
+												   candidate->inner_relids);
+
+		if (part_prune_info)
+		{
+			JoinPartitionPruneInfo *jpinfo;
+
+			jpinfo = makeNode(JoinPartitionPruneInfo);
+
+			jpinfo->part_prune_info = part_prune_info;
+			jpinfo->paramid = assign_special_exec_param(root);
+			jpinfo->nplans = list_length(subpaths);
+
+			candidate->joinpartprune_info_list =
+				lappend(candidate->joinpartprune_info_list, jpinfo);
+
+			result = bms_add_member(result, jpinfo->paramid);
+		}
+	}
+
+	return result;
+}
+
+/*
+ * prepare_join_partition_prune_candidate
+ * 		Check if join partition pruning is possible at this join and if so
+ * 		collect information required to build JoinPartitionPruneInfos.
+ *
+ * Note that we may build more than one JoinPartitionPruneInfo at one join, for
+ * different Append/MergeAppend paths.
+ */
+void
+prepare_join_partition_prune_candidate(PlannerInfo *root, JoinPath *jpath)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+
+	if (!enable_partition_pruning)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now do not perform join partition pruning for parallel hashjoin.
+	 */
+	if (jpath->path.parallel_workers > 0)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * We cannot perform join partition pruning if the outer is the
+	 * non-nullable side.
+	 */
+	if (!(jpath->jointype == JOIN_INNER ||
+		  jpath->jointype == JOIN_SEMI ||
+		  jpath->jointype == JOIN_RIGHT ||
+		  jpath->jointype == JOIN_RIGHT_ANTI))
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now we only support HashJoin.
+	 */
+	if (jpath->path.pathtype != T_HashJoin)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	candidate = makeNode(JoinPartitionPruneCandidateInfo);
+	candidate->joinrestrictinfo = jpath->joinrestrictinfo;
+	candidate->inner_relids = jpath->innerjoinpath->parent->relids;
+	candidate->inner_rows = jpath->innerjoinpath->parent->rows;
+	candidate->joinpartprune_info_list = NIL;
+
+	root->join_partition_prune_candidates =
+		lappend(root->join_partition_prune_candidates, candidate);
+}
+
+/*
+ * get_join_partition_prune_candidate
+ *		Pop out the JoinPartitionPruneCandidateInfo for this join and retrieve
+ *		the JoinPartitionPruneInfos.
+ */
+List *
+get_join_partition_prune_candidate(PlannerInfo *root)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+	List   *result;
+
+	candidate = llast(root->join_partition_prune_candidates);
+	root->join_partition_prune_candidates =
+		list_delete_last(root->join_partition_prune_candidates);
+
+	if (candidate == NULL)
+		return NIL;
+
+	result = candidate->joinpartprune_info_list;
+
+	pfree(candidate);
+
+	return result;
+}
+
 /*
  * add_part_relids
  *		Add new info to a list of Bitmapsets of partitioned relids.
@@ -428,6 +620,8 @@ add_part_relids(List *allpartrelids, Bitmapset *partrelids)
  * partrelids: Set of RT indexes identifying relevant partitioned tables
  *   within a single partitioning hierarchy
  * relid_subplan_map[]: maps child relation relids to subplan indexes
+ * available_rels: the relid set of rels whose Vars may be used for
+ *   pruning.
  * matchedsubplans: on success, receives the set of subplan indexes which
  *   were matched to this partition hierarchy
  *
@@ -440,6 +634,7 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 							  List *prunequal,
 							  Bitmapset *partrelids,
 							  int *relid_subplan_map,
+							  Bitmapset *available_rels,
 							  Bitmapset **matchedsubplans)
 {
 	RelOptInfo *targetpart = NULL;
@@ -539,8 +734,8 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 		 * pruning steps and detects whether there's any possibly-useful quals
 		 * that would require per-scan pruning.
 		 */
-		gen_partprune_steps(subpart, partprunequal, PARTTARGET_INITIAL,
-							&context);
+		gen_partprune_steps(subpart, partprunequal, available_rels,
+							PARTTARGET_INITIAL, &context);
 
 		if (context.contradictory)
 		{
@@ -567,14 +762,15 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			initial_pruning_steps = NIL;
 
 		/*
-		 * If no exec Params appear in potentially-usable pruning clauses,
-		 * then there's no point in even thinking about per-scan pruning.
+		 * If no exec Params or available Vars appear in potentially-usable
+		 * pruning clauses, then there's no point in even thinking about
+		 * per-scan pruning.
 		 */
-		if (context.has_exec_param)
+		if (context.has_exec_param || context.has_vars)
 		{
 			/* ... OK, we'd better think about it */
-			gen_partprune_steps(subpart, partprunequal, PARTTARGET_EXEC,
-								&context);
+			gen_partprune_steps(subpart, partprunequal, available_rels,
+								PARTTARGET_EXEC, &context);
 
 			if (context.contradictory)
 			{
@@ -587,11 +783,14 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			/*
 			 * Detect which exec Params actually got used; the fact that some
 			 * were in available clauses doesn't mean we actually used them.
-			 * Skip per-scan pruning if there are none.
 			 */
 			execparamids = get_partkey_exec_paramids(exec_pruning_steps);
 
-			if (bms_is_empty(execparamids))
+			/*
+			 * Skip per-scan pruning if there are none used exec Params and
+			 * there are none available Vars.
+			 */
+			if (bms_is_empty(execparamids) && !context.has_vars)
 				exec_pruning_steps = NIL;
 		}
 		else
@@ -703,6 +902,9 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  *		Process 'clauses' (typically a rel's baserestrictinfo list of clauses)
  *		and create a list of "partition pruning steps".
  *
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
+ *
  * 'target' tells whether to generate pruning steps for planning (use
  * immutable clauses only), or for executor startup (use any allowable
  * clause except ones containing PARAM_EXEC Params), or for executor
@@ -712,12 +914,13 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  * some subsidiary flags; see the GeneratePruningStepsContext typedef.
  */
 static void
-gen_partprune_steps(RelOptInfo *rel, List *clauses, PartClauseTarget target,
-					GeneratePruningStepsContext *context)
+gen_partprune_steps(RelOptInfo *rel, List *clauses, Bitmapset *available_rels,
+					PartClauseTarget target, GeneratePruningStepsContext *context)
 {
 	/* Initialize all output values to zero/false/NULL */
 	memset(context, 0, sizeof(GeneratePruningStepsContext));
 	context->rel = rel;
+	context->available_rels = available_rels;
 	context->target = target;
 
 	/*
@@ -773,7 +976,7 @@ prune_append_rel_partitions(RelOptInfo *rel)
 	 * If the clauses are found to be contradictory, we can return the empty
 	 * set.
 	 */
-	gen_partprune_steps(rel, clauses, PARTTARGET_PLANNER,
+	gen_partprune_steps(rel, clauses, NULL, PARTTARGET_PLANNER,
 						&gcontext);
 	if (gcontext.contradictory)
 		return NULL;
@@ -1957,9 +2160,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) expr))
+			if (contain_forbidden_var_clause((Node *) expr, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -2155,9 +2359,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) rightop))
+			if (contain_forbidden_var_clause((Node *) rightop, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -3727,3 +3932,54 @@ partkey_datum_from_expr(PartitionPruneContext *context,
 		*value = ExecEvalExprSwitchContext(exprstate, ectx, isnull);
 	}
 }
+
+/*
+ * contain_forbidden_var_clause
+ *	  Recursively scan a clause to discover whether it contains any Var nodes
+ *	  (of the current query level) that do not belong to relations in
+ *	  context->available_rels.
+ *
+ *	  Returns true if any such varnode found.
+ *
+ * Does not examine subqueries, therefore must only be used after reduction
+ * of sublinks to subplans!
+ */
+static bool
+contain_forbidden_var_clause(Node *node, GeneratePruningStepsContext *context)
+{
+	return contain_forbidden_var_clause_walker(node, context);
+}
+
+static bool
+contain_forbidden_var_clause_walker(Node *node, GeneratePruningStepsContext *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		*var = (Var *) node;
+
+		if (var->varlevelsup != 0)
+			return false;
+
+		if (!bms_is_member(var->varno, context->available_rels))
+			return true;		/* abort the tree traversal and return true */
+
+		context->has_vars = true;
+
+		if (context->target != PARTTARGET_EXEC)
+			return true;		/* abort the tree traversal and return true */
+
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+		return true;
+	if (IsA(node, PlaceHolderVar))
+	{
+		if (((PlaceHolderVar *) node)->phlevelsup == 0)
+			return true;		/* abort the tree traversal and return true */
+		/* else fall through to check the contained expr */
+	}
+	return expression_tree_walker(node, contain_forbidden_var_clause_walker,
+								  (void *) context);
+}
diff --git a/src/include/executor/execPartition.h b/src/include/executor/execPartition.h
index c09bc83b2a..7e46f0baf6 100644
--- a/src/include/executor/execPartition.h
+++ b/src/include/executor/execPartition.h
@@ -121,11 +121,26 @@ typedef struct PartitionPruneState
 	PartitionPruningData *partprunedata[FLEXIBLE_ARRAY_MEMBER];
 } PartitionPruneState;
 
+/*
+ * JoinPartitionPruneState - State object required for plan nodes to perform
+ * join partition pruning.
+ */
+typedef struct JoinPartitionPruneState
+{
+	PartitionPruneState *part_prune_state;
+	int			paramid;
+	int			nplans;
+	bool		finished;
+	Bitmapset  *part_prune_result;
+} JoinPartitionPruneState;
+
 extern PartitionPruneState *ExecInitPartitionPruning(PlanState *planstate,
 													 int n_total_subplans,
 													 PartitionPruneInfo *pruneinfo,
 													 Bitmapset **initially_valid_subplans);
+extern List *ExecInitJoinpartpruneList(PlanState *planstate, List *joinpartprune_info_list);
 extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-										   bool initial_prune);
+										   bool initial_prune,
+										   PlanState *planstate);
 
 #endif							/* EXECPARTITION_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 444a5f0fd5..8f02af1f10 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2685,6 +2685,9 @@ typedef struct HashState
 
 	/* Parallel hash state. */
 	struct ParallelHashJoinState *parallel_state;
+
+	/* Infos for join partition pruning. */
+	List *joinpartprune_state_list;
 } HashState;
 
 /* ----------------
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 534692bee1..da7803448a 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,9 @@ struct PlannerInfo
 	/* not-yet-assigned NestLoopParams */
 	List	   *curOuterParams;
 
+	/* a stack of JoinPartitionPruneInfos */
+	List	   *join_partition_prune_candidates;
+
 	/*
 	 * These fields are workspace for setrefs.c.  Each is an array
 	 * corresponding to glob->subplans.  (We could probably teach
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index b4ef6bc44c..964bc85123 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -275,6 +275,9 @@ typedef struct Append
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } Append;
 
 /* ----------------
@@ -310,6 +313,9 @@ typedef struct MergeAppend
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } MergeAppend;
 
 /* ----------------
@@ -1206,6 +1212,7 @@ typedef struct Hash
 	bool		skewInherit;	/* is outer join rel an inheritance tree? */
 	/* all other info is in the parent HashJoin node */
 	Cardinality rows_total;		/* estimate total rows if parallel_aware */
+	List	   *joinpartprune_info_list;	/* infos for join partition pruning */
 } Hash;
 
 /* ----------------
@@ -1552,6 +1559,35 @@ typedef struct PartitionPruneStepCombine
 	List	   *source_stepids;
 } PartitionPruneStepCombine;
 
+/*
+ * JoinPartitionPruneCandidateInfo - Information required to build
+ * JoinPartitionPruneInfos.
+ */
+typedef struct JoinPartitionPruneCandidateInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	List	   *joinrestrictinfo;
+	Bitmapset  *inner_relids;
+	double		inner_rows;
+	List	   *joinpartprune_info_list;
+} JoinPartitionPruneCandidateInfo;
+
+/*
+ * JoinPartitionPruneInfo - Details required to allow the executor to prune
+ * partitions during join.
+ */
+typedef struct JoinPartitionPruneInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	PartitionPruneInfo *part_prune_info;
+	int			paramid;
+	int			nplans;
+} JoinPartitionPruneInfo;
+
 
 /*
  * Plan invalidation info
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index b1c51a4e70..5ccd3c62d4 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -212,5 +212,9 @@ extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *targ
 extern double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 								   Path *bitmapqual, double loop_count,
 								   Cost *cost_p, double *tuples_p);
+extern double compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+									 Cost append_total_cost, int append_nplans,
+									 Relids inner_relids, double inner_rows,
+									 List *prunequal);
 
 #endif							/* COST_H */
diff --git a/src/include/partitioning/partprune.h b/src/include/partitioning/partprune.h
index bd490d154f..5187485c88 100644
--- a/src/include/partitioning/partprune.h
+++ b/src/include/partitioning/partprune.h
@@ -19,6 +19,8 @@
 
 struct PlannerInfo;				/* avoid including pathnodes.h here */
 struct RelOptInfo;
+struct Path;
+struct JoinPath;
 
 
 /*
@@ -73,7 +75,15 @@ typedef struct PartitionPruneContext
 extern PartitionPruneInfo *make_partition_pruneinfo(struct PlannerInfo *root,
 													struct RelOptInfo *parentrel,
 													List *subpaths,
-													List *prunequal);
+													List *prunequal,
+													Bitmapset *available_rels);
+extern Bitmapset *make_join_partition_pruneinfos(struct PlannerInfo *root,
+												 struct RelOptInfo *parentrel,
+												 struct Path *best_path,
+												 List *subpaths);
+extern void prepare_join_partition_prune_candidate(struct PlannerInfo *root,
+												   struct JoinPath *jpath);
+extern List *get_join_partition_prune_candidate(struct PlannerInfo *root);
 extern Bitmapset *prune_append_rel_partitions(struct RelOptInfo *rel);
 extern Bitmapset *get_matching_partitions(PartitionPruneContext *context,
 										  List *pruning_steps);
diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 9a4c48c055..a08e7a1f0a 100644
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3003,6 +3003,92 @@ order by tbl1.col1, tprt.col1;
 ------+------
 (0 rows)
 
+-- join partition pruning
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+                         explain_join_partition_pruning                         
+--------------------------------------------------------------------------------
+ Hash Right Join (actual rows=2 loops=1)
+   Output: p1.col1, p2.col1, t.col1
+   Hash Cond: ((p1.col1 = t.col1) AND (p2.col1 = t.col1))
+   ->  Hash Join (actual rows=3 loops=1)
+         Output: p1.col1, p2.col1
+         Hash Cond: (p1.col1 = p2.col1)
+         ->  Append (actual rows=3 loops=1)
+               Join Partition Pruning: $0
+               ->  Seq Scan on public.tprt_1 p1_1 (never executed)
+                     Output: p1_1.col1
+               ->  Seq Scan on public.tprt_2 p1_2 (actual rows=3 loops=1)
+                     Output: p1_2.col1
+               ->  Seq Scan on public.tprt_3 p1_3 (never executed)
+                     Output: p1_3.col1
+               ->  Seq Scan on public.tprt_4 p1_4 (never executed)
+                     Output: p1_4.col1
+               ->  Seq Scan on public.tprt_5 p1_5 (never executed)
+                     Output: p1_5.col1
+               ->  Seq Scan on public.tprt_6 p1_6 (never executed)
+                     Output: p1_6.col1
+         ->  Hash (actual rows=3 loops=1)
+               Output: p2.col1
+               Buckets: 1024  Batches: 1  Memory Usage: NkB
+               ->  Append (actual rows=3 loops=1)
+                     Join Partition Pruning: $1
+                     ->  Seq Scan on public.tprt_1 p2_1 (never executed)
+                           Output: p2_1.col1
+                     ->  Seq Scan on public.tprt_2 p2_2 (actual rows=3 loops=1)
+                           Output: p2_2.col1
+                     ->  Seq Scan on public.tprt_3 p2_3 (never executed)
+                           Output: p2_3.col1
+                     ->  Seq Scan on public.tprt_4 p2_4 (never executed)
+                           Output: p2_4.col1
+                     ->  Seq Scan on public.tprt_5 p2_5 (never executed)
+                           Output: p2_5.col1
+                     ->  Seq Scan on public.tprt_6 p2_6 (never executed)
+                           Output: p2_6.col1
+   ->  Hash (actual rows=2 loops=1)
+         Output: t.col1
+         Buckets: 1024  Batches: 1  Memory Usage: NkB
+         Partition Prune: $0, $1
+         ->  Seq Scan on public.tbl1 t (actual rows=2 loops=1)
+               Output: t.col1
+(43 rows)
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+ col1 | col1 | col1 
+------+------+------
+  501 |  501 |  501
+  505 |  505 |  505
+(2 rows)
+
 drop table tbl1, tprt;
 -- Test with columns defined in varying orders between each level
 create table part_abc (a int not null, b int not null, c int not null) partition by list (a);
diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index 7bf3920827..fc5982edcf 100644
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -727,6 +727,45 @@ select tbl1.col1, tprt.col1 from tbl1
 inner join tprt on tbl1.col1 = tprt.col1
 order by tbl1.col1, tprt.col1;
 
+-- join partition pruning
+
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+
 drop table tbl1, tprt;
 
 -- Test with columns defined in varying orders between each level
-- 
2.31.0

From 465c96b2c84df1c6dd2ffa3001759c2f18ab3867 Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Mon, 14 Aug 2023 14:55:26 +0800
Subject: [PATCH v7] Support run-time partition pruning for hash join

If we have a hash join with an Append node on the outer side, something
like

 Hash Join
   Hash Cond: (pt.a = t.a)
   ->  Append
         ->  Seq Scan on pt_p1 pt_1
         ->  Seq Scan on pt_p2 pt_2
         ->  Seq Scan on pt_p3 pt_3
   ->  Hash
         ->  Seq Scan on t

We can actually prune those subnodes of the Append that cannot possibly
contain any matching tuples from the other side of the join.  To do
that, when building the Hash table, for each row from the inner side we
can compute the minimum set of subnodes that can possibly match the join
condition.  When we have built the Hash table and start to execute the
Append node, we should have known which subnodes are survived and thus
can skip other subnodes.

This patch implements this idea.
---
 src/backend/commands/explain.c                |  61 ++++
 src/backend/executor/execPartition.c          | 127 +++++++-
 src/backend/executor/nodeAppend.c             |  32 +-
 src/backend/executor/nodeHash.c               |  75 +++++
 src/backend/executor/nodeHashjoin.c           |  10 +
 src/backend/executor/nodeMergeAppend.c        |  22 +-
 src/backend/optimizer/path/costsize.c         | 106 +++++++
 src/backend/optimizer/plan/createplan.c       |  49 ++-
 src/backend/optimizer/plan/setrefs.c          |  61 ++++
 src/backend/partitioning/partprune.c          | 298 ++++++++++++++++--
 src/include/executor/execPartition.h          |  17 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/pathnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |  36 +++
 src/include/optimizer/cost.h                  |   4 +
 src/include/partitioning/partprune.h          |  12 +-
 src/test/regress/expected/partition_prune.out |  86 +++++
 src/test/regress/sql/partition_prune.sql      |  39 +++
 18 files changed, 992 insertions(+), 49 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index a9d5056af4..0a5591b95f 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -18,6 +18,7 @@
 #include "commands/createas.h"
 #include "commands/defrem.h"
 #include "commands/prepare.h"
+#include "executor/execPartition.h"
 #include "foreign/fdwapi.h"
 #include "jit/jit.h"
 #include "nodes/extensible.h"
@@ -117,6 +118,9 @@ static void show_instrumentation_count(const char *qlabel, int which,
 									   PlanState *planstate, ExplainState *es);
 static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
 static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
+static void show_join_pruning_result_info(Bitmapset *join_prune_paramids,
+										  ExplainState *es);
+static void show_joinpartprune_info(HashState *hashstate, ExplainState *es);
 static const char *explain_get_index_name(Oid indexId);
 static bool peek_buffer_usage(ExplainState *es, const BufferUsage *usage);
 static void show_buffer_usage(ExplainState *es, const BufferUsage *usage);
@@ -2115,9 +2119,17 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			show_incremental_sort_info(castNode(IncrementalSortState, planstate),
 									   es);
 			break;
+		case T_Append:
+			if (es->verbose)
+				show_join_pruning_result_info(((Append *) plan)->join_prune_paramids,
+											  es);
+			break;
 		case T_MergeAppend:
 			show_merge_append_keys(castNode(MergeAppendState, planstate),
 								   ancestors, es);
+			if (es->verbose)
+				show_join_pruning_result_info(((MergeAppend *) plan)->join_prune_paramids,
+											  es);
 			break;
 		case T_Result:
 			show_upper_qual((List *) ((Result *) plan)->resconstantqual,
@@ -2133,6 +2145,8 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			break;
 		case T_Hash:
 			show_hash_info(castNode(HashState, planstate), es);
+			if (es->verbose)
+				show_joinpartprune_info(castNode(HashState, planstate), es);
 			break;
 		case T_Memoize:
 			show_memoize_info(castNode(MemoizeState, planstate), ancestors,
@@ -3573,6 +3587,53 @@ show_eval_params(Bitmapset *bms_params, ExplainState *es)
 		ExplainPropertyList("Params Evaluated", params, es);
 }
 
+/*
+ * Show join partition pruning results at Append/MergeAppend nodes.
+ */
+static void
+show_join_pruning_result_info(Bitmapset *join_prune_paramids, ExplainState *es)
+{
+	int			paramid = -1;
+	List	   *params = NIL;
+
+	if (bms_is_empty(join_prune_paramids))
+		return;
+
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Join Partition Pruning", params, es);
+}
+
+/*
+ * Show join partition pruning infos at Hash nodes.
+ */
+static void
+show_joinpartprune_info(HashState *hashstate, ExplainState *es)
+{
+	List	   *params = NIL;
+	ListCell   *lc;
+
+	if (!hashstate->joinpartprune_state_list)
+		return;
+
+	foreach(lc, hashstate->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		char		param[32];
+
+		snprintf(param, sizeof(param), "$%d", jpstate->paramid);
+		params = lappend(params, pstrdup(param));
+	}
+
+	ExplainPropertyList("Partition Prune", params, es);
+}
+
 /*
  * Fetch the name of an index in an EXPLAIN
  *
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 64fcb012db..d715827972 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -196,6 +196,8 @@ static void find_matching_subplans_recurse(PartitionPruningData *prunedata,
 										   PartitionedRelPruningData *pprune,
 										   bool initial_prune,
 										   Bitmapset **validsubplans);
+static bool get_join_prune_matching_subplans(PlanState *planstate,
+											 Bitmapset **partset);
 
 
 /*
@@ -1805,7 +1807,7 @@ ExecInitPartitionPruning(PlanState *planstate,
 	 * Perform an initial partition prune pass, if required.
 	 */
 	if (prunestate->do_initial_prune)
-		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true);
+		*initially_valid_subplans = ExecFindMatchingSubPlans(prunestate, true, NULL);
 	else
 	{
 		/* No pruning, so we'll need to initialize all subplans */
@@ -1835,6 +1837,37 @@ ExecInitPartitionPruning(PlanState *planstate,
 	return prunestate;
 }
 
+/*
+ * ExecInitJoinpartpruneList
+ *		Initialize data structures needed for join partition pruning
+ */
+List *
+ExecInitJoinpartpruneList(PlanState *planstate,
+						  List *joinpartprune_info_list)
+{
+	ListCell   *lc;
+	List	   *result = NIL;
+
+	foreach(lc, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(lc);
+		JoinPartitionPruneState *jpstate = palloc(sizeof(JoinPartitionPruneState));
+
+		jpstate->part_prune_state =
+			CreatePartitionPruneState(planstate, jpinfo->part_prune_info);
+		Assert(jpstate->part_prune_state->do_exec_prune);
+
+		jpstate->paramid = jpinfo->paramid;
+		jpstate->nplans = jpinfo->nplans;
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+
+		result = lappend(result, jpstate);
+	}
+
+	return result;
+}
+
 /*
  * CreatePartitionPruneState
  *		Build the data structure required for calling ExecFindMatchingSubPlans
@@ -2272,7 +2305,9 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
 /*
  * ExecFindMatchingSubPlans
  *		Determine which subplans match the pruning steps detailed in
- *		'prunestate' for the current comparison expression values.
+ *		'prunestate' if any for the current comparison expression values, and
+ *		meanwhile match the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.
  *
  * Pass initial_prune if PARAM_EXEC Params cannot yet be evaluated.  This
  * differentiates the initial executor-time pruning step from later
@@ -2280,11 +2315,30 @@ PartitionPruneFixSubPlanMap(PartitionPruneState *prunestate,
  */
 Bitmapset *
 ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-						 bool initial_prune)
+						 bool initial_prune,
+						 PlanState *planstate)
 {
 	Bitmapset  *result = NULL;
 	MemoryContext oldcontext;
 	int			i;
+	Bitmapset  *join_prune_partset = NULL;
+	bool		do_join_prune;
+
+	/* Retrieve the join partition pruning results if any */
+	do_join_prune =
+		get_join_prune_matching_subplans(planstate, &join_prune_partset);
+
+	/*
+	 * Either we're here on partition prune done according to the pruning steps
+	 * detailed in 'prunestate', or we have done join partition prune.
+	 */
+	Assert(do_join_prune || prunestate != NULL);
+
+	/*
+	 * If there is no 'prunestate', then rely entirely on join pruning.
+	 */
+	if (prunestate == NULL)
+		return join_prune_partset;
 
 	/*
 	 * Either we're here on the initial prune done during pruning
@@ -2325,6 +2379,10 @@ ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
 	/* Add in any subplans that partition pruning didn't account for */
 	result = bms_add_members(result, prunestate->other_subplans);
 
+	/* Intersect join partition pruning results */
+	if (do_join_prune)
+		result = bms_intersect(result, join_prune_partset);
+
 	MemoryContextSwitchTo(oldcontext);
 
 	/* Copy result out of the temp context before we reset it */
@@ -2395,3 +2453,66 @@ find_matching_subplans_recurse(PartitionPruningData *prunedata,
 		}
 	}
 }
+
+/*
+ * get_join_prune_matching_subplans
+ *		Retrieve the join partition pruning results if any stored in
+ *		Append/MergeAppend node's join_prune_paramids.  Return true if we can
+ *		do join partition pruning, otherwise return false.
+ *
+ * Adds valid (non-prunable) subplan IDs to *partset
+ */
+static bool
+get_join_prune_matching_subplans(PlanState *planstate, Bitmapset **partset)
+{
+	Bitmapset  *join_prune_paramids;
+	int			nplans;
+	int			paramid;
+
+	if (planstate == NULL)
+		return false;
+
+	if (IsA(planstate, AppendState))
+	{
+		join_prune_paramids =
+			((Append *) planstate->plan)->join_prune_paramids;
+		nplans = ((AppendState *) planstate)->as_nplans;
+	}
+	else if (IsA(planstate, MergeAppendState))
+	{
+		join_prune_paramids =
+			((MergeAppend *) planstate->plan)->join_prune_paramids;
+		nplans = ((MergeAppendState *) planstate)->ms_nplans;
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(planstate));
+		return false;
+	}
+
+	if (bms_is_empty(join_prune_paramids))
+		return false;
+
+	Assert(nplans > 0);
+	*partset = bms_add_range(NULL, 0, nplans - 1);
+
+	paramid = -1;
+	while ((paramid = bms_next_member(join_prune_paramids, paramid)) >= 0)
+	{
+		ParamExecData *param;
+		JoinPartitionPruneState *jpstate;
+
+		param = &(planstate->state->es_param_exec_vals[paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		jpstate = (JoinPartitionPruneState *) DatumGetPointer(param->value);
+
+		if (jpstate != NULL)
+			*partset = bms_intersect(*partset, jpstate->part_prune_result);
+		else	/* the Hash node for this pruning has not been executed */
+			elog(WARNING, "Join partition pruning $%d has not been performed yet.",
+				 paramid);
+	}
+
+	return true;
+}
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index ca0f54d676..cd5ec550fc 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -151,11 +151,13 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill as_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill as_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 		{
 			appendstate->as_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 			appendstate->as_valid_subplans_identified = true;
@@ -170,10 +172,18 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		appendstate->as_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
-		appendstate->as_valid_subplans_identified = true;
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		appendstate->as_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill as_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+		{
+			appendstate->as_valid_subplans = validsubplans;
+			appendstate->as_valid_subplans_identified = true;
+		}
 	}
 
 	/*
@@ -580,7 +590,7 @@ choose_next_subplan_locally(AppendState *node)
 		else if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 		}
 
@@ -647,7 +657,7 @@ choose_next_subplan_for_leader(AppendState *node)
 		if (!node->as_valid_subplans_identified)
 		{
 			node->as_valid_subplans =
-				ExecFindMatchingSubPlans(node->as_prune_state, false);
+				ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 			node->as_valid_subplans_identified = true;
 
 			/*
@@ -723,7 +733,7 @@ choose_next_subplan_for_worker(AppendState *node)
 	else if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		mark_invalid_subplans_as_finished(node);
@@ -876,7 +886,7 @@ ExecAppendAsyncBegin(AppendState *node)
 	if (!node->as_valid_subplans_identified)
 	{
 		node->as_valid_subplans =
-			ExecFindMatchingSubPlans(node->as_prune_state, false);
+			ExecFindMatchingSubPlans(node->as_prune_state, false, &node->ps);
 		node->as_valid_subplans_identified = true;
 
 		classify_matching_subplans(node);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 61480733a1..39658b9fc5 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -30,6 +30,7 @@
 #include "access/parallel.h"
 #include "catalog/pg_statistic.h"
 #include "commands/tablespace.h"
+#include "executor/execPartition.h"
 #include "executor/executor.h"
 #include "executor/hashjoin.h"
 #include "executor/nodeHash.h"
@@ -47,6 +48,8 @@ static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBatches(HashJoinTable hashtable);
 static void ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable);
+static void ExecJoinPartitionPrune(HashState *node);
+static void ExecStoreJoinPartitionPruneResult(HashState *node);
 static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node,
 								  int mcvsToUse);
 static void ExecHashSkewTableInsert(HashJoinTable hashtable,
@@ -188,8 +191,14 @@ MultiExecPrivateHash(HashState *node)
 			}
 			hashtable->totalTuples += 1;
 		}
+
+		/* Perform join partition pruning */
+		ExecJoinPartitionPrune(node);
 	}
 
+	/* Store the surviving partitions for Append/MergeAppend nodes */
+	ExecStoreJoinPartitionPruneResult(node);
+
 	/* resize the hash table if needed (NTUP_PER_BUCKET exceeded) */
 	if (hashtable->nbuckets != hashtable->nbuckets_optimal)
 		ExecHashIncreaseNumBuckets(hashtable);
@@ -400,6 +409,12 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	hashstate->hashkeys =
 		ExecInitExprList(node->hashkeys, (PlanState *) hashstate);
 
+	/*
+	 * initialize join partition pruning infos
+	 */
+	hashstate->joinpartprune_state_list =
+		ExecInitJoinpartpruneList(&hashstate->ps, node->joinpartprune_info_list);
+
 	return hashstate;
 }
 
@@ -1609,6 +1624,56 @@ ExecParallelHashIncreaseNumBuckets(HashJoinTable hashtable)
 	}
 }
 
+/*
+ * ExecJoinPartitionPrune
+ *		Perform join partition pruning at this join for each
+ *		JoinPartitionPruneState.
+ */
+static void
+ExecJoinPartitionPrune(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		Bitmapset	   *matching_subPlans;
+
+		if (jpstate->finished)
+			continue;
+
+		matching_subPlans =
+			ExecFindMatchingSubPlans(jpstate->part_prune_state, false, NULL);
+		jpstate->part_prune_result =
+			bms_add_members(jpstate->part_prune_result, matching_subPlans);
+
+		if (bms_num_members(jpstate->part_prune_result) == jpstate->nplans)
+			jpstate->finished = true;
+	}
+}
+
+/*
+ * ExecStoreJoinPartitionPruneResult
+ *		For each JoinPartitionPruneState, store the set of surviving partitions
+ *		to make it available for the Append/MergeAppend node.
+ */
+static void
+ExecStoreJoinPartitionPruneResult(HashState *node)
+{
+	ListCell   *lc;
+
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+		ParamExecData	   *param;
+
+		param = &(node->ps.state->es_param_exec_vals[jpstate->paramid]);
+		Assert(param->execPlan == NULL);
+		Assert(!param->isnull);
+		param->value = PointerGetDatum(jpstate);
+	}
+}
+
 /*
  * ExecHashTableInsert
  *		insert a tuple into the hash table depending on the hash value
@@ -2353,6 +2418,16 @@ void
 ExecReScanHash(HashState *node)
 {
 	PlanState  *outerPlan = outerPlanState(node);
+	ListCell   *lc;
+
+	/* reset the state in JoinPartitionPruneStates */
+	foreach(lc, node->joinpartprune_state_list)
+	{
+		JoinPartitionPruneState *jpstate = (JoinPartitionPruneState *) lfirst(lc);
+
+		jpstate->finished = false;
+		jpstate->part_prune_result = NULL;
+	}
 
 	/*
 	 * if chgParam of subnode is not null then plan will be re-scanned by
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index dbf114cd5e..2a9d2c6482 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -310,6 +310,16 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 					 */
 					node->hj_FirstOuterTupleSlot = NULL;
 				}
+				else if (hashNode->joinpartprune_state_list != NIL)
+				{
+					/*
+					 * Give the hash node a chance to run join partition
+					 * pruning if there is any JoinPartitionPruneState that can
+					 * be evaluated at it.  So do not apply the empty-outer
+					 * optimization in this case.
+					 */
+					node->hj_FirstOuterTupleSlot = NULL;
+				}
 				else if (HJ_FILL_OUTER(node) ||
 						 (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
 						  !node->hj_OuterNotEmpty))
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index e1b9b984a7..df921ad5ad 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -99,11 +99,13 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		nplans = bms_num_members(validsubplans);
 
 		/*
-		 * When no run-time pruning is required and there's at least one
-		 * subplan, we can fill ms_valid_subplans immediately, preventing
-		 * later calls to ExecFindMatchingSubPlans.
+		 * When no run-time pruning or join pruning is required and there's at
+		 * least one subplan, we can fill ms_valid_subplans immediately,
+		 * preventing later calls to ExecFindMatchingSubPlans.
 		 */
-		if (!prunestate->do_exec_prune && nplans > 0)
+		if (!prunestate->do_exec_prune &&
+			bms_is_empty(node->join_prune_paramids) &&
+			nplans > 0)
 			mergestate->ms_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
 	}
 	else
@@ -115,9 +117,15 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		 * subplans as valid; they must also all be initialized.
 		 */
 		Assert(nplans > 0);
-		mergestate->ms_valid_subplans = validsubplans =
-			bms_add_range(NULL, 0, nplans - 1);
+		validsubplans = bms_add_range(NULL, 0, nplans - 1);
 		mergestate->ms_prune_state = NULL;
+
+		/*
+		 * When join pruning is not enabled we can fill ms_valid_subplans
+		 * immediately, preventing later calls to ExecFindMatchingSubPlans.
+		 */
+		if (bms_is_empty(node->join_prune_paramids))
+			mergestate->ms_valid_subplans = validsubplans;
 	}
 
 	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
@@ -218,7 +226,7 @@ ExecMergeAppend(PlanState *pstate)
 		 */
 		if (node->ms_valid_subplans == NULL)
 			node->ms_valid_subplans =
-				ExecFindMatchingSubPlans(node->ms_prune_state, false);
+				ExecFindMatchingSubPlans(node->ms_prune_state, false, &node->ps);
 
 		/*
 		 * First time through: pull the first tuple from each valid subplan,
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 83a0aed051..382413e666 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -172,6 +172,10 @@ static void get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
 static bool has_indexed_join_quals(NestPath *path);
 static double approx_tuple_count(PlannerInfo *root, JoinPath *path,
 								 List *quals);
+static double get_joinrel_matching_outer_size(PlannerInfo *root,
+											  RelOptInfo *outer_rel,
+											  Relids inner_relids,
+											  List *restrictlist);
 static double calc_joinrel_size_estimate(PlannerInfo *root,
 										 RelOptInfo *joinrel,
 										 RelOptInfo *outer_rel,
@@ -5408,6 +5412,61 @@ get_parameterized_joinrel_size(PlannerInfo *root, RelOptInfo *rel,
 	return nrows;
 }
 
+/*
+ * get_joinrel_matching_outer_size
+ *		Make a size estimate for the outer side that matches the inner side.
+ */
+static double
+get_joinrel_matching_outer_size(PlannerInfo *root,
+								RelOptInfo *outer_rel,
+								Relids inner_relids,
+								List *restrictlist)
+{
+	double		nrows;
+	Selectivity fkselec;
+	Selectivity jselec;
+	SpecialJoinInfo *sjinfo;
+	SpecialJoinInfo sjinfo_data;
+
+	sjinfo = &sjinfo_data;
+	sjinfo->type = T_SpecialJoinInfo;
+	sjinfo->min_lefthand = outer_rel->relids;
+	sjinfo->min_righthand = inner_relids;
+	sjinfo->syn_lefthand = outer_rel->relids;
+	sjinfo->syn_righthand = inner_relids;
+	sjinfo->jointype = JOIN_SEMI;
+	sjinfo->ojrelid = 0;
+	sjinfo->commute_above_l = NULL;
+	sjinfo->commute_above_r = NULL;
+	sjinfo->commute_below_l = NULL;
+	sjinfo->commute_below_r = NULL;
+	/* we don't bother trying to make the remaining fields valid */
+	sjinfo->lhs_strict = false;
+	sjinfo->semi_can_btree = false;
+	sjinfo->semi_can_hash = false;
+	sjinfo->semi_operators = NIL;
+	sjinfo->semi_rhs_exprs = NIL;
+
+	fkselec = get_foreign_key_join_selectivity(root,
+											   outer_rel->relids,
+											   inner_relids,
+											   sjinfo,
+											   &restrictlist);
+	jselec = clauselist_selectivity(root,
+									restrictlist,
+									0,
+									sjinfo->jointype,
+									sjinfo);
+
+	nrows = outer_rel->rows * fkselec * jselec;
+	nrows = clamp_row_est(nrows);
+
+	/* For safety, make sure result is not more than the base estimate */
+	if (nrows > outer_rel->rows)
+		nrows = outer_rel->rows;
+	return nrows;
+}
+
 /*
  * calc_joinrel_size_estimate
  *		Workhorse for set_joinrel_size_estimates and
@@ -6529,3 +6588,50 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 
 	return pages_fetched;
 }
+
+/*
+ * compute_partprune_cost
+ *		Compute the overhead of join partition pruning.
+ */
+double
+compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+					   Cost append_total_cost, int append_nplans,
+					   Relids inner_relids, double inner_rows,
+					   List *prunequal)
+{
+	Cost		prune_cost;
+	Cost		saved_cost;
+	double		matching_outer_rows;
+	double		unmatched_nplans;
+
+	switch (appendrel->part_scheme->strategy)
+	{
+
+		case PARTITION_STRATEGY_LIST:
+		case PARTITION_STRATEGY_RANGE:
+			prune_cost = cpu_operator_cost * LOG2(append_nplans) * inner_rows;
+			break;
+		case PARTITION_STRATEGY_HASH:
+			prune_cost = cpu_operator_cost * append_nplans * inner_rows;
+			break;
+		default:
+			elog(ERROR, "unexpected partition strategy: %d",
+				 (int) appendrel->part_scheme->strategy);
+			break;
+	}
+
+	matching_outer_rows =
+		get_joinrel_matching_outer_size(root,
+										appendrel,
+										inner_relids,
+										prunequal);
+
+	/*
+	 * We assume that each outer joined row occupies one new partition.  This
+	 * is really the worst case.
+	 */
+	unmatched_nplans = append_nplans - Min(matching_outer_rows, append_nplans);
+	saved_cost = (unmatched_nplans / append_nplans) * append_total_cost;
+
+	return prune_cost - saved_cost;
+}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 610f4a56d6..55cd3bb616 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -242,7 +242,8 @@ static Hash *make_hash(Plan *lefttree,
 					   List *hashkeys,
 					   Oid skewTable,
 					   AttrNumber skewColumn,
-					   bool skewInherit);
+					   bool skewInherit,
+					   List *joinpartprune_info_list);
 static MergeJoin *make_mergejoin(List *tlist,
 								 List *joinclauses, List *otherclauses,
 								 List *mergeclauses,
@@ -342,6 +343,7 @@ create_plan(PlannerInfo *root, Path *best_path)
 	/* Initialize this module's workspace in PlannerInfo */
 	root->curOuterRels = NULL;
 	root->curOuterParams = NIL;
+	root->join_partition_prune_candidates = NIL;
 
 	/* Recursively process the path tree, demanding the correct tlist result */
 	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
@@ -369,6 +371,8 @@ create_plan(PlannerInfo *root, Path *best_path)
 	if (root->curOuterParams != NIL)
 		elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
 
+	Assert(root->join_partition_prune_candidates == NIL);
+
 	/*
 	 * Reset plan_params to ensure param IDs used for nestloop params are not
 	 * re-used later
@@ -1223,6 +1227,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	int			nasyncplans = 0;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 	int			nodenumsortkeys = 0;
 	AttrNumber *nodeSortColIdx = NULL;
 	Oid		   *nodeSortOperators = NULL;
@@ -1377,6 +1382,8 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1399,13 +1406,20 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 			partpruneinfo =
 				make_partition_pruneinfo(root, rel,
 										 best_path->subpaths,
-										 prunequal);
+										 prunequal,
+										 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	plan->appendplans = subplans;
 	plan->nasyncplans = nasyncplans;
 	plan->first_partial_plan = best_path->first_partial_path;
 	plan->part_prune_info = partpruneinfo;
+	plan->join_prune_paramids = join_prune_paramids;
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -1445,6 +1459,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	ListCell   *subpaths;
 	RelOptInfo *rel = best_path->path.parent;
 	PartitionPruneInfo *partpruneinfo = NULL;
+	Bitmapset  *join_prune_paramids = NULL;
 
 	/*
 	 * We don't have the actual creation of the MergeAppend node split out
@@ -1541,6 +1556,8 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 	 * If any quals exist, they may be useful to perform further partition
 	 * pruning during execution.  Gather information needed by the executor to
 	 * do partition pruning.
+	 *
+	 * Also gather information needed by the executor to do join pruning.
 	 */
 	if (enable_partition_pruning)
 	{
@@ -1554,11 +1571,18 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
 		if (prunequal != NIL)
 			partpruneinfo = make_partition_pruneinfo(root, rel,
 													 best_path->subpaths,
-													 prunequal);
+													 prunequal,
+													 NULL);
+
+		join_prune_paramids =
+			make_join_partition_pruneinfos(root, rel,
+										   (Path *) best_path,
+										   best_path->subpaths);
 	}
 
 	node->mergeplans = subplans;
 	node->part_prune_info = partpruneinfo;
+	node->join_prune_paramids = join_prune_paramids;
 
 	/*
 	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
@@ -4743,6 +4767,13 @@ create_hashjoin_plan(PlannerInfo *root,
 	AttrNumber	skewColumn = InvalidAttrNumber;
 	bool		skewInherit = false;
 	ListCell   *lc;
+	List	   *joinpartprune_info_list;
+
+	/*
+	 * Collect information required to build JoinPartitionPruneInfos at this
+	 * join.
+	 */
+	prepare_join_partition_prune_candidate(root, &best_path->jpath);
 
 	/*
 	 * HashJoin can project, so we don't have to demand exact tlists from the
@@ -4754,6 +4785,11 @@ create_hashjoin_plan(PlannerInfo *root,
 	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
 									 (best_path->num_batches > 1) ? CP_SMALL_TLIST : 0);
 
+	/*
+	 * Retrieve all the JoinPartitionPruneInfos for this join.
+	 */
+	joinpartprune_info_list = get_join_partition_prune_candidate(root);
+
 	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
 									 CP_SMALL_TLIST);
 
@@ -4859,7 +4895,8 @@ create_hashjoin_plan(PlannerInfo *root,
 						  inner_hashkeys,
 						  skewTable,
 						  skewColumn,
-						  skewInherit);
+						  skewInherit,
+						  joinpartprune_info_list);
 
 	/*
 	 * Set Hash node's startup & total costs equal to total cost of input
@@ -5986,7 +6023,8 @@ make_hash(Plan *lefttree,
 		  List *hashkeys,
 		  Oid skewTable,
 		  AttrNumber skewColumn,
-		  bool skewInherit)
+		  bool skewInherit,
+		  List *joinpartprune_info_list)
 {
 	Hash	   *node = makeNode(Hash);
 	Plan	   *plan = &node->plan;
@@ -6000,6 +6038,7 @@ make_hash(Plan *lefttree,
 	node->skewTable = skewTable;
 	node->skewColumn = skewColumn;
 	node->skewInherit = skewInherit;
+	node->joinpartprune_info_list = joinpartprune_info_list;
 
 	return node;
 }
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 42603dbc7c..573446b989 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -155,6 +155,11 @@ static Plan *set_mergeappend_references(PlannerInfo *root,
 										MergeAppend *mplan,
 										int rtoffset);
 static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_joinpartitionprune_references(PlannerInfo *root,
+											  List *joinpartprune_info_list,
+											  indexed_tlist *outer_itlist,
+											  int rtoffset,
+											  double num_exec);
 static Relids offset_relid_set(Relids relids, int rtoffset);
 static Node *fix_scan_expr(PlannerInfo *root, Node *node,
 						   int rtoffset, double num_exec);
@@ -1896,6 +1901,62 @@ set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset)
 
 	/* Hash nodes don't have their own quals */
 	Assert(plan->qual == NIL);
+
+	set_joinpartitionprune_references(root,
+									  hplan->joinpartprune_info_list,
+									  outer_itlist,
+									  rtoffset,
+									  NUM_EXEC_TLIST(plan));
+}
+
+/*
+ * set_joinpartitionprune_references
+ *	   Do set_plan_references processing on JoinPartitionPruneInfos
+ */
+static void
+set_joinpartitionprune_references(PlannerInfo *root,
+								  List *joinpartprune_info_list,
+								  indexed_tlist *outer_itlist,
+								  int rtoffset,
+								  double num_exec)
+{
+	ListCell   *l;
+
+	foreach(l, joinpartprune_info_list)
+	{
+		JoinPartitionPruneInfo *jpinfo = (JoinPartitionPruneInfo *) lfirst(l);
+		ListCell   *l1;
+
+		foreach(l1, jpinfo->part_prune_info->prune_infos)
+		{
+			List	   *prune_infos = lfirst(l1);
+			ListCell   *l2;
+
+			foreach(l2, prune_infos)
+			{
+				PartitionedRelPruneInfo *pinfo = lfirst(l2);
+
+				pinfo->rtindex += rtoffset;
+
+				pinfo->initial_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->initial_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+				pinfo->exec_pruning_steps = (List *)
+					fix_upper_expr(root,
+								   (Node *) pinfo->exec_pruning_steps,
+								   outer_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   num_exec);
+			}
+		}
+	}
 }
 
 /*
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 9006afd9d2..c0cf7c3c86 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -48,7 +48,9 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/cost.h"
 #include "optimizer/optimizer.h"
+#include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/restrictinfo.h"
 #include "parser/parsetree.h"
 #include "partitioning/partbounds.h"
 #include "partitioning/partprune.h"
@@ -102,15 +104,16 @@ typedef enum PartClauseTarget
  *
  * gen_partprune_steps() initializes and returns an instance of this struct.
  *
- * Note that has_mutable_op, has_mutable_arg, and has_exec_param are set if
- * we found any potentially-useful-for-pruning clause having those properties,
- * whether or not we actually used the clause in the steps list.  This
- * definition allows us to skip the PARTTARGET_EXEC pass in some cases.
+ * Note that has_mutable_op, has_mutable_arg, has_exec_param and has_vars are
+ * set if we found any potentially-useful-for-pruning clause having those
+ * properties, whether or not we actually used the clause in the steps list.
+ * This definition allows us to skip the PARTTARGET_EXEC pass in some cases.
  */
 typedef struct GeneratePruningStepsContext
 {
 	/* Copies of input arguments for gen_partprune_steps: */
 	RelOptInfo *rel;			/* the partitioned relation */
+	Bitmapset  *available_rels;	/* rels whose Vars may be used for pruning */
 	PartClauseTarget target;	/* use-case we're generating steps for */
 	/* Result data: */
 	List	   *steps;			/* list of PartitionPruneSteps */
@@ -118,6 +121,7 @@ typedef struct GeneratePruningStepsContext
 	bool		has_mutable_arg;	/* clauses include any mutable comparison
 									 * values, *other than* exec params */
 	bool		has_exec_param; /* clauses include any PARAM_EXEC params */
+	bool		has_vars;		/* clauses include any Vars from 'available_rels' */
 	bool		contradictory;	/* clauses were proven self-contradictory */
 	/* Working state: */
 	int			next_step_id;
@@ -143,8 +147,10 @@ static List *make_partitionedrel_pruneinfo(PlannerInfo *root,
 										   List *prunequal,
 										   Bitmapset *partrelids,
 										   int *relid_subplan_map,
+										   Bitmapset *available_rels,
 										   Bitmapset **matchedsubplans);
 static void gen_partprune_steps(RelOptInfo *rel, List *clauses,
+								Bitmapset *available_rels,
 								PartClauseTarget target,
 								GeneratePruningStepsContext *context);
 static List *gen_partprune_steps_internal(GeneratePruningStepsContext *context,
@@ -203,6 +209,10 @@ static PartClauseMatchStatus match_boolean_partition_clause(Oid partopfamily,
 static void partkey_datum_from_expr(PartitionPruneContext *context,
 									Expr *expr, int stateidx,
 									Datum *value, bool *isnull);
+static bool contain_forbidden_var_clause(Node *node,
+										 GeneratePruningStepsContext *context);
+static bool contain_forbidden_var_clause_walker(Node *node,
+												GeneratePruningStepsContext *context);
 
 
 /*
@@ -215,11 +225,14 @@ static void partkey_datum_from_expr(PartitionPruneContext *context,
  * 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).
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
  */
 PartitionPruneInfo *
 make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 						 List *subpaths,
-						 List *prunequal)
+						 List *prunequal,
+						 Bitmapset *available_rels)
 {
 	PartitionPruneInfo *pruneinfo;
 	Bitmapset  *allmatchedsubplans = NULL;
@@ -312,6 +325,7 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 												  prunequal,
 												  partrelids,
 												  relid_subplan_map,
+												  available_rels,
 												  &matchedsubplans);
 
 		/* When pruning is possible, record the matched subplans */
@@ -359,6 +373,184 @@ make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 	return pruneinfo;
 }
 
+/*
+ * make_join_partition_pruneinfos
+ *		Builds one JoinPartitionPruneInfo for each join at which join partition
+ *		pruning is possible for this appendrel.
+ *
+ * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
+ * of scan paths for its child rels.
+ */
+Bitmapset *
+make_join_partition_pruneinfos(PlannerInfo *root, RelOptInfo *parentrel,
+							   Path *best_path, List *subpaths)
+{
+	Bitmapset  *result = NULL;
+	ListCell   *lc;
+
+	if (!IS_PARTITIONED_REL(parentrel))
+		return NULL;
+
+	foreach(lc, root->join_partition_prune_candidates)
+	{
+		JoinPartitionPruneCandidateInfo *candidate =
+			(JoinPartitionPruneCandidateInfo *) lfirst(lc);
+		PartitionPruneInfo *part_prune_info;
+		List	   *prunequal;
+		Relids		joinrelids;
+		ListCell   *l;
+		double		prune_cost;
+
+		if (candidate == NULL)
+			continue;
+
+		/*
+		 * Identify all joinclauses that are movable to this appendrel given
+		 * this inner side relids.  Only those clauses can be used for join
+		 * partition pruning.
+		 */
+		joinrelids = bms_union(parentrel->relids, candidate->inner_relids);
+		prunequal = NIL;
+		foreach(l, candidate->joinrestrictinfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+
+			if (join_clause_is_movable_into(rinfo,
+											parentrel->relids,
+											joinrelids))
+				prunequal = lappend(prunequal, rinfo);
+		}
+
+		if (prunequal == NIL)
+			continue;
+
+		/*
+		 * Check the overhead of this pruning
+		 */
+		prune_cost = compute_partprune_cost(root,
+											parentrel,
+											best_path->total_cost,
+											list_length(subpaths),
+											candidate->inner_relids,
+											candidate->inner_rows,
+											prunequal);
+		if (prune_cost > 0)
+			continue;
+
+		part_prune_info = make_partition_pruneinfo(root, parentrel,
+												   subpaths,
+												   prunequal,
+												   candidate->inner_relids);
+
+		if (part_prune_info)
+		{
+			JoinPartitionPruneInfo *jpinfo;
+
+			jpinfo = makeNode(JoinPartitionPruneInfo);
+
+			jpinfo->part_prune_info = part_prune_info;
+			jpinfo->paramid = assign_special_exec_param(root);
+			jpinfo->nplans = list_length(subpaths);
+
+			candidate->joinpartprune_info_list =
+				lappend(candidate->joinpartprune_info_list, jpinfo);
+
+			result = bms_add_member(result, jpinfo->paramid);
+		}
+	}
+
+	return result;
+}
+
+/*
+ * prepare_join_partition_prune_candidate
+ * 		Check if join partition pruning is possible at this join and if so
+ * 		collect information required to build JoinPartitionPruneInfos.
+ *
+ * Note that we may build more than one JoinPartitionPruneInfo at one join, for
+ * different Append/MergeAppend paths.
+ */
+void
+prepare_join_partition_prune_candidate(PlannerInfo *root, JoinPath *jpath)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+
+	if (!enable_partition_pruning)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now do not perform join partition pruning for parallel hashjoin.
+	 */
+	if (jpath->path.parallel_workers > 0)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * We cannot perform join partition pruning if the outer is the
+	 * non-nullable side.
+	 */
+	if (!(jpath->jointype == JOIN_INNER ||
+		  jpath->jointype == JOIN_SEMI ||
+		  jpath->jointype == JOIN_RIGHT ||
+		  jpath->jointype == JOIN_RIGHT_ANTI))
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	/*
+	 * For now we only support HashJoin.
+	 */
+	if (jpath->path.pathtype != T_HashJoin)
+	{
+		root->join_partition_prune_candidates =
+			lappend(root->join_partition_prune_candidates, NULL);
+		return;
+	}
+
+	candidate = makeNode(JoinPartitionPruneCandidateInfo);
+	candidate->joinrestrictinfo = jpath->joinrestrictinfo;
+	candidate->inner_relids = jpath->innerjoinpath->parent->relids;
+	candidate->inner_rows = jpath->innerjoinpath->parent->rows;
+	candidate->joinpartprune_info_list = NIL;
+
+	root->join_partition_prune_candidates =
+		lappend(root->join_partition_prune_candidates, candidate);
+}
+
+/*
+ * get_join_partition_prune_candidate
+ *		Pop out the JoinPartitionPruneCandidateInfo for this join and retrieve
+ *		the JoinPartitionPruneInfos.
+ */
+List *
+get_join_partition_prune_candidate(PlannerInfo *root)
+{
+	JoinPartitionPruneCandidateInfo *candidate;
+	List   *result;
+
+	candidate = llast(root->join_partition_prune_candidates);
+	root->join_partition_prune_candidates =
+		list_delete_last(root->join_partition_prune_candidates);
+
+	if (candidate == NULL)
+		return NIL;
+
+	result = candidate->joinpartprune_info_list;
+
+	pfree(candidate);
+
+	return result;
+}
+
 /*
  * add_part_relids
  *		Add new info to a list of Bitmapsets of partitioned relids.
@@ -427,6 +619,8 @@ add_part_relids(List *allpartrelids, Bitmapset *partrelids)
  * partrelids: Set of RT indexes identifying relevant partitioned tables
  *   within a single partitioning hierarchy
  * relid_subplan_map[]: maps child relation relids to subplan indexes
+ * available_rels: the relid set of rels whose Vars may be used for
+ *   pruning.
  * matchedsubplans: on success, receives the set of subplan indexes which
  *   were matched to this partition hierarchy
  *
@@ -439,6 +633,7 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 							  List *prunequal,
 							  Bitmapset *partrelids,
 							  int *relid_subplan_map,
+							  Bitmapset *available_rels,
 							  Bitmapset **matchedsubplans)
 {
 	RelOptInfo *targetpart = NULL;
@@ -538,8 +733,8 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 		 * pruning steps and detects whether there's any possibly-useful quals
 		 * that would require per-scan pruning.
 		 */
-		gen_partprune_steps(subpart, partprunequal, PARTTARGET_INITIAL,
-							&context);
+		gen_partprune_steps(subpart, partprunequal, available_rels,
+							PARTTARGET_INITIAL, &context);
 
 		if (context.contradictory)
 		{
@@ -566,14 +761,15 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			initial_pruning_steps = NIL;
 
 		/*
-		 * If no exec Params appear in potentially-usable pruning clauses,
-		 * then there's no point in even thinking about per-scan pruning.
+		 * If no exec Params or available Vars appear in potentially-usable
+		 * pruning clauses, then there's no point in even thinking about
+		 * per-scan pruning.
 		 */
-		if (context.has_exec_param)
+		if (context.has_exec_param || context.has_vars)
 		{
 			/* ... OK, we'd better think about it */
-			gen_partprune_steps(subpart, partprunequal, PARTTARGET_EXEC,
-								&context);
+			gen_partprune_steps(subpart, partprunequal, available_rels,
+								PARTTARGET_EXEC, &context);
 
 			if (context.contradictory)
 			{
@@ -586,11 +782,14 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
 			/*
 			 * Detect which exec Params actually got used; the fact that some
 			 * were in available clauses doesn't mean we actually used them.
-			 * Skip per-scan pruning if there are none.
 			 */
 			execparamids = get_partkey_exec_paramids(exec_pruning_steps);
 
-			if (bms_is_empty(execparamids))
+			/*
+			 * Skip per-scan pruning if there are none used exec Params and
+			 * there are none available Vars.
+			 */
+			if (bms_is_empty(execparamids) && !context.has_vars)
 				exec_pruning_steps = NIL;
 		}
 		else
@@ -702,6 +901,9 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  *		Process 'clauses' (typically a rel's baserestrictinfo list of clauses)
  *		and create a list of "partition pruning steps".
  *
+ * 'available_rels' is the relid set of rels whose Vars may be used for
+ * pruning.
+ *
  * 'target' tells whether to generate pruning steps for planning (use
  * immutable clauses only), or for executor startup (use any allowable
  * clause except ones containing PARAM_EXEC Params), or for executor
@@ -711,12 +913,13 @@ make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
  * some subsidiary flags; see the GeneratePruningStepsContext typedef.
  */
 static void
-gen_partprune_steps(RelOptInfo *rel, List *clauses, PartClauseTarget target,
-					GeneratePruningStepsContext *context)
+gen_partprune_steps(RelOptInfo *rel, List *clauses, Bitmapset *available_rels,
+					PartClauseTarget target, GeneratePruningStepsContext *context)
 {
 	/* Initialize all output values to zero/false/NULL */
 	memset(context, 0, sizeof(GeneratePruningStepsContext));
 	context->rel = rel;
+	context->available_rels = available_rels;
 	context->target = target;
 
 	/*
@@ -772,7 +975,7 @@ prune_append_rel_partitions(RelOptInfo *rel)
 	 * If the clauses are found to be contradictory, we can return the empty
 	 * set.
 	 */
-	gen_partprune_steps(rel, clauses, PARTTARGET_PLANNER,
+	gen_partprune_steps(rel, clauses, NULL, PARTTARGET_PLANNER,
 						&gcontext);
 	if (gcontext.contradictory)
 		return NULL;
@@ -2020,9 +2223,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) expr))
+			if (contain_forbidden_var_clause((Node *) expr, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -2218,9 +2422,10 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
-			 * We can never prune using an expression that contains Vars.
+			 * We can never prune using an expression that contains Vars except
+			 * for Vars belonging to context->available_rels.
 			 */
-			if (contain_var_clause((Node *) rightop))
+			if (contain_forbidden_var_clause((Node *) rightop, context))
 				return PARTCLAUSE_UNSUPPORTED;
 
 			/*
@@ -3790,3 +3995,54 @@ partkey_datum_from_expr(PartitionPruneContext *context,
 		*value = ExecEvalExprSwitchContext(exprstate, ectx, isnull);
 	}
 }
+
+/*
+ * contain_forbidden_var_clause
+ *	  Recursively scan a clause to discover whether it contains any Var nodes
+ *	  (of the current query level) that do not belong to relations in
+ *	  context->available_rels.
+ *
+ *	  Returns true if any such varnode found.
+ *
+ * Does not examine subqueries, therefore must only be used after reduction
+ * of sublinks to subplans!
+ */
+static bool
+contain_forbidden_var_clause(Node *node, GeneratePruningStepsContext *context)
+{
+	return contain_forbidden_var_clause_walker(node, context);
+}
+
+static bool
+contain_forbidden_var_clause_walker(Node *node, GeneratePruningStepsContext *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		*var = (Var *) node;
+
+		if (var->varlevelsup != 0)
+			return false;
+
+		if (!bms_is_member(var->varno, context->available_rels))
+			return true;		/* abort the tree traversal and return true */
+
+		context->has_vars = true;
+
+		if (context->target != PARTTARGET_EXEC)
+			return true;		/* abort the tree traversal and return true */
+
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+		return true;
+	if (IsA(node, PlaceHolderVar))
+	{
+		if (((PlaceHolderVar *) node)->phlevelsup == 0)
+			return true;		/* abort the tree traversal and return true */
+		/* else fall through to check the contained expr */
+	}
+	return expression_tree_walker(node, contain_forbidden_var_clause_walker,
+								  (void *) context);
+}
diff --git a/src/include/executor/execPartition.h b/src/include/executor/execPartition.h
index c09bc83b2a..7e46f0baf6 100644
--- a/src/include/executor/execPartition.h
+++ b/src/include/executor/execPartition.h
@@ -121,11 +121,26 @@ typedef struct PartitionPruneState
 	PartitionPruningData *partprunedata[FLEXIBLE_ARRAY_MEMBER];
 } PartitionPruneState;
 
+/*
+ * JoinPartitionPruneState - State object required for plan nodes to perform
+ * join partition pruning.
+ */
+typedef struct JoinPartitionPruneState
+{
+	PartitionPruneState *part_prune_state;
+	int			paramid;
+	int			nplans;
+	bool		finished;
+	Bitmapset  *part_prune_result;
+} JoinPartitionPruneState;
+
 extern PartitionPruneState *ExecInitPartitionPruning(PlanState *planstate,
 													 int n_total_subplans,
 													 PartitionPruneInfo *pruneinfo,
 													 Bitmapset **initially_valid_subplans);
+extern List *ExecInitJoinpartpruneList(PlanState *planstate, List *joinpartprune_info_list);
 extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate,
-										   bool initial_prune);
+										   bool initial_prune,
+										   PlanState *planstate);
 
 #endif							/* EXECPARTITION_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 9259352672..3cfd011a0a 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2684,6 +2684,9 @@ typedef struct HashState
 
 	/* Parallel hash state. */
 	struct ParallelHashJoinState *parallel_state;
+
+	/* Infos for join partition pruning. */
+	List *joinpartprune_state_list;
 } HashState;
 
 /* ----------------
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 534692bee1..da7803448a 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,9 @@ struct PlannerInfo
 	/* not-yet-assigned NestLoopParams */
 	List	   *curOuterParams;
 
+	/* a stack of JoinPartitionPruneInfos */
+	List	   *join_partition_prune_candidates;
+
 	/*
 	 * These fields are workspace for setrefs.c.  Each is an array
 	 * corresponding to glob->subplans.  (We could probably teach
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index b4ef6bc44c..964bc85123 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -275,6 +275,9 @@ typedef struct Append
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } Append;
 
 /* ----------------
@@ -310,6 +313,9 @@ typedef struct MergeAppend
 
 	/* Info for run-time subplan pruning; NULL if we're not doing that */
 	struct PartitionPruneInfo *part_prune_info;
+
+	/* Info for join partition pruning; NULL if we're not doing that */
+	Bitmapset  *join_prune_paramids;
 } MergeAppend;
 
 /* ----------------
@@ -1206,6 +1212,7 @@ typedef struct Hash
 	bool		skewInherit;	/* is outer join rel an inheritance tree? */
 	/* all other info is in the parent HashJoin node */
 	Cardinality rows_total;		/* estimate total rows if parallel_aware */
+	List	   *joinpartprune_info_list;	/* infos for join partition pruning */
 } Hash;
 
 /* ----------------
@@ -1552,6 +1559,35 @@ typedef struct PartitionPruneStepCombine
 	List	   *source_stepids;
 } PartitionPruneStepCombine;
 
+/*
+ * JoinPartitionPruneCandidateInfo - Information required to build
+ * JoinPartitionPruneInfos.
+ */
+typedef struct JoinPartitionPruneCandidateInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	List	   *joinrestrictinfo;
+	Bitmapset  *inner_relids;
+	double		inner_rows;
+	List	   *joinpartprune_info_list;
+} JoinPartitionPruneCandidateInfo;
+
+/*
+ * JoinPartitionPruneInfo - Details required to allow the executor to prune
+ * partitions during join.
+ */
+typedef struct JoinPartitionPruneInfo
+{
+	pg_node_attr(no_equal, no_query_jumble)
+
+	NodeTag		type;
+	PartitionPruneInfo *part_prune_info;
+	int			paramid;
+	int			nplans;
+} JoinPartitionPruneInfo;
+
 
 /*
  * Plan invalidation info
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index b1c51a4e70..5ccd3c62d4 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -212,5 +212,9 @@ extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *targ
 extern double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 								   Path *bitmapqual, double loop_count,
 								   Cost *cost_p, double *tuples_p);
+extern double compute_partprune_cost(PlannerInfo *root, RelOptInfo *appendrel,
+									 Cost append_total_cost, int append_nplans,
+									 Relids inner_relids, double inner_rows,
+									 List *prunequal);
 
 #endif							/* COST_H */
diff --git a/src/include/partitioning/partprune.h b/src/include/partitioning/partprune.h
index bd490d154f..5187485c88 100644
--- a/src/include/partitioning/partprune.h
+++ b/src/include/partitioning/partprune.h
@@ -19,6 +19,8 @@
 
 struct PlannerInfo;				/* avoid including pathnodes.h here */
 struct RelOptInfo;
+struct Path;
+struct JoinPath;
 
 
 /*
@@ -73,7 +75,15 @@ typedef struct PartitionPruneContext
 extern PartitionPruneInfo *make_partition_pruneinfo(struct PlannerInfo *root,
 													struct RelOptInfo *parentrel,
 													List *subpaths,
-													List *prunequal);
+													List *prunequal,
+													Bitmapset *available_rels);
+extern Bitmapset *make_join_partition_pruneinfos(struct PlannerInfo *root,
+												 struct RelOptInfo *parentrel,
+												 struct Path *best_path,
+												 List *subpaths);
+extern void prepare_join_partition_prune_candidate(struct PlannerInfo *root,
+												   struct JoinPath *jpath);
+extern List *get_join_partition_prune_candidate(struct PlannerInfo *root);
 extern Bitmapset *prune_append_rel_partitions(struct RelOptInfo *rel);
 extern Bitmapset *get_matching_partitions(PartitionPruneContext *context,
 										  List *pruning_steps);
diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 9c20a24982..7f51a3986e 100644
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3144,6 +3144,92 @@ order by tbl1.col1, tprt.col1;
 ------+------
 (0 rows)
 
+-- join partition pruning
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+                         explain_join_partition_pruning                         
+--------------------------------------------------------------------------------
+ Hash Right Join (actual rows=2 loops=1)
+   Output: p1.col1, p2.col1, t.col1
+   Hash Cond: ((p1.col1 = t.col1) AND (p2.col1 = t.col1))
+   ->  Hash Join (actual rows=3 loops=1)
+         Output: p1.col1, p2.col1
+         Hash Cond: (p1.col1 = p2.col1)
+         ->  Append (actual rows=3 loops=1)
+               Join Partition Pruning: $0
+               ->  Seq Scan on public.tprt_1 p1_1 (never executed)
+                     Output: p1_1.col1
+               ->  Seq Scan on public.tprt_2 p1_2 (actual rows=3 loops=1)
+                     Output: p1_2.col1
+               ->  Seq Scan on public.tprt_3 p1_3 (never executed)
+                     Output: p1_3.col1
+               ->  Seq Scan on public.tprt_4 p1_4 (never executed)
+                     Output: p1_4.col1
+               ->  Seq Scan on public.tprt_5 p1_5 (never executed)
+                     Output: p1_5.col1
+               ->  Seq Scan on public.tprt_6 p1_6 (never executed)
+                     Output: p1_6.col1
+         ->  Hash (actual rows=3 loops=1)
+               Output: p2.col1
+               Buckets: 1024  Batches: 1  Memory Usage: NkB
+               ->  Append (actual rows=3 loops=1)
+                     Join Partition Pruning: $1
+                     ->  Seq Scan on public.tprt_1 p2_1 (never executed)
+                           Output: p2_1.col1
+                     ->  Seq Scan on public.tprt_2 p2_2 (actual rows=3 loops=1)
+                           Output: p2_2.col1
+                     ->  Seq Scan on public.tprt_3 p2_3 (never executed)
+                           Output: p2_3.col1
+                     ->  Seq Scan on public.tprt_4 p2_4 (never executed)
+                           Output: p2_4.col1
+                     ->  Seq Scan on public.tprt_5 p2_5 (never executed)
+                           Output: p2_5.col1
+                     ->  Seq Scan on public.tprt_6 p2_6 (never executed)
+                           Output: p2_6.col1
+   ->  Hash (actual rows=2 loops=1)
+         Output: t.col1
+         Buckets: 1024  Batches: 1  Memory Usage: NkB
+         Partition Prune: $0, $1
+         ->  Seq Scan on public.tbl1 t (actual rows=2 loops=1)
+               Output: t.col1
+(43 rows)
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+ col1 | col1 | col1 
+------+------+------
+  501 |  501 |  501
+  505 |  505 |  505
+(2 rows)
+
 drop table tbl1, tprt;
 -- Test with columns defined in varying orders between each level
 create table part_abc (a int not null, b int not null, c int not null) partition by list (a);
diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index a09b27d820..2d1e96d51e 100644
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -764,6 +764,45 @@ select tbl1.col1, tprt.col1 from tbl1
 inner join tprt on tbl1.col1 = tprt.col1
 order by tbl1.col1, tprt.col1;
 
+-- join partition pruning
+
+-- The 'Memory Usage' from the Hash node can vary between machines.  Let's just
+-- replace the number with an 'N'.
+-- We need to run EXPLAIN ANALYZE because we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
+create function explain_join_partition_pruning(text) returns setof text
+language plpgsql as
+$$
+declare
+    ln text;
+begin
+    for ln in
+        execute format('explain (analyze, verbose, costs off, summary off, timing off) %s',
+            $1)
+    loop
+        ln := regexp_replace(ln, 'Memory Usage: \d+', 'Memory Usage: N');
+        return next ln;
+    end loop;
+end;
+$$;
+
+delete from tbl1;
+insert into tbl1 values (501), (505);
+analyze tbl1, tprt;
+
+set enable_nestloop = off;
+set enable_mergejoin = off;
+set enable_hashjoin = on;
+
+select explain_join_partition_pruning('
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;');
+
+select * from tprt p1
+   inner join tprt p2 on p1.col1 = p2.col1
+   right join tbl1 t on p1.col1 = t.col1 and p2.col1 = t.col1;
+
 drop table tbl1, tprt;
 
 -- Test with columns defined in varying orders between each level
-- 
2.31.0