From 887627ec4455a70a716ce56f386f71df953cdf64 Mon Sep 17 00:00:00 2001
From: Amit Langote <amitlan@postgresql.org>
Date: Thu, 22 Aug 2024 19:38:13 +0900
Subject: [PATCH v51 3/3] Handle CachedPlan invalidation in the executor

This commit makes changes to handle cases where a cached plan
becomes invalid before deferred locks on prunable relations are taken.

* Add checks at various points in ExecutorStart() and its called
  functions to determine if the plan becomes invalid. If detected,
  the function and its callers return immediately. A previous commit
  ensures any partially initialized PlanState tree objects are cleaned
  up appropriately.

* Introduce ExecutorStartExt(), a wrapper over ExecutorStart(), to
  handle cases where plan initialization is aborted due to invalidation.
  ExecutorStartExt() creates a new transient CachedPlan if needed and
  retries execution. This new entry point is only required for sites
  using plancache.c. It requires passing the QueryDesc, eflags,
  CachedPlanSource, and query_index (index in CachedPlanSource.query_list).

* Add GetSingleCachedPlan() in plancache.c to create a transient
  CachedPlan for a specified query in the given CachedPlanSource.

This also adds isolation tests using the delay_execution test module
to verify scenarios where a CachedPlan becomes invalid before the
deferred locks are taken.

All ExecutorStart_hook implementations now must add the following
block after the ExecutorStart() call to ensure it doesn't work with an
invalid plan:

    /* The plan may have become invalid during ExecutorStart() */
    if (!ExecPlanStillValid(queryDesc->estate))
        return;

Reviewed-by: Robert Haas
Discussion: https://postgr.es/m/CA+HiwqFGkMSge6TgC9KQzde0ohpAycLQuV7ooitEEpbKB0O_mg@mail.gmail.comk
---
 contrib/auto_explain/auto_explain.c           |   4 +
 .../pg_stat_statements/pg_stat_statements.c   |   4 +
 contrib/postgres_fdw/postgres_fdw.c           |  36 +++-
 src/backend/commands/explain.c                |   8 +-
 src/backend/commands/portalcmds.c             |   1 +
 src/backend/commands/prepare.c                |  10 +-
 src/backend/commands/trigger.c                |  14 ++
 src/backend/executor/README                   |  32 +++-
 src/backend/executor/execMain.c               |  91 ++++++++-
 src/backend/executor/execParallel.c           |   4 +-
 src/backend/executor/execPartition.c          |  10 +
 src/backend/executor/execProcnode.c           |   7 +
 src/backend/executor/execUtils.c              |  42 ++++-
 src/backend/executor/nodeAgg.c                |   2 +
 src/backend/executor/nodeAppend.c             |  12 +-
 src/backend/executor/nodeBitmapAnd.c          |   2 +
 src/backend/executor/nodeBitmapHeapscan.c     |   4 +
 src/backend/executor/nodeBitmapIndexscan.c    |   6 +-
 src/backend/executor/nodeBitmapOr.c           |   2 +
 src/backend/executor/nodeCustom.c             |   2 +
 src/backend/executor/nodeForeignscan.c        |   4 +
 src/backend/executor/nodeGather.c             |   2 +
 src/backend/executor/nodeGatherMerge.c        |   2 +
 src/backend/executor/nodeGroup.c              |   2 +
 src/backend/executor/nodeHash.c               |   2 +
 src/backend/executor/nodeHashjoin.c           |   4 +
 src/backend/executor/nodeIncrementalSort.c    |   2 +
 src/backend/executor/nodeIndexonlyscan.c      |   7 +-
 src/backend/executor/nodeIndexscan.c          |   8 +-
 src/backend/executor/nodeLimit.c              |   2 +
 src/backend/executor/nodeLockRows.c           |   2 +
 src/backend/executor/nodeMaterial.c           |   2 +
 src/backend/executor/nodeMemoize.c            |   2 +
 src/backend/executor/nodeMergeAppend.c        |   6 +-
 src/backend/executor/nodeMergejoin.c          |   4 +
 src/backend/executor/nodeModifyTable.c        |  13 ++
 src/backend/executor/nodeNestloop.c           |   4 +
 src/backend/executor/nodeProjectSet.c         |   2 +
 src/backend/executor/nodeRecursiveunion.c     |   4 +
 src/backend/executor/nodeResult.c             |   2 +
 src/backend/executor/nodeSamplescan.c         |   3 +
 src/backend/executor/nodeSeqscan.c            |   3 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSort.c               |   2 +
 src/backend/executor/nodeSubqueryscan.c       |   2 +
 src/backend/executor/nodeTidrangescan.c       |   2 +
 src/backend/executor/nodeTidscan.c            |   2 +
 src/backend/executor/nodeUnique.c             |   2 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/executor/spi.c                    |  19 +-
 src/backend/tcop/postgres.c                   |   4 +-
 src/backend/tcop/pquery.c                     |  31 +++-
 src/backend/utils/cache/plancache.c           |  50 +++++
 src/backend/utils/mmgr/portalmem.c            |   4 +-
 src/include/commands/explain.h                |   1 +
 src/include/commands/trigger.h                |   1 +
 src/include/executor/execdesc.h               |   1 +
 src/include/executor/executor.h               |  18 ++
 src/include/nodes/execnodes.h                 |   1 +
 src/include/utils/plancache.h                 |  18 ++
 src/include/utils/portal.h                    |   4 +-
 src/test/modules/delay_execution/Makefile     |   3 +-
 .../modules/delay_execution/delay_execution.c |  63 ++++++-
 .../expected/cached-plan-inval.out            | 175 ++++++++++++++++++
 src/test/modules/delay_execution/meson.build  |   1 +
 .../specs/cached-plan-inval.spec              |  65 +++++++
 66 files changed, 790 insertions(+), 58 deletions(-)
 create mode 100644 src/test/modules/delay_execution/expected/cached-plan-inval.out
 create mode 100644 src/test/modules/delay_execution/specs/cached-plan-inval.spec

diff --git a/contrib/auto_explain/auto_explain.c b/contrib/auto_explain/auto_explain.c
index 677c135f59..3675ce9a88 100644
--- a/contrib/auto_explain/auto_explain.c
+++ b/contrib/auto_explain/auto_explain.c
@@ -300,6 +300,10 @@ explain_ExecutorStart(QueryDesc *queryDesc, int eflags)
 	else
 		standard_ExecutorStart(queryDesc, eflags);
 
+	/* The plan may have become invalid during ExecutorStart() */
+	if (!ExecPlanStillValid(queryDesc->estate))
+		return;
+
 	if (auto_explain_enabled())
 	{
 		/*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 362d222f63..98a328b79f 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -992,6 +992,10 @@ pgss_ExecutorStart(QueryDesc *queryDesc, int eflags)
 	else
 		standard_ExecutorStart(queryDesc, eflags);
 
+	/* The plan may have become invalid during ExecutorStart() */
+	if (!ExecPlanStillValid(queryDesc->estate))
+		return;
+
 	/*
 	 * If query has queryId zero, don't track it.  This prevents double
 	 * counting of optimizable statements that are directly contained in
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index adc62576d1..65f4ffe5ee 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -2144,7 +2144,11 @@ postgresEndForeignModify(EState *estate,
 {
 	PgFdwModifyState *fmstate = (PgFdwModifyState *) resultRelInfo->ri_FdwState;
 
-	/* If fmstate is NULL, we are in EXPLAIN; nothing to do */
+	/*
+	 * fmstate could be NULL under two conditions: during an EXPLAIN
+	 * operation or if BeginForeignModify() hasn't been invoked.
+	 * In either case, no action is required.
+	 */
 	if (fmstate == NULL)
 		return;
 
@@ -2650,8 +2654,9 @@ postgresBeginDirectModify(ForeignScanState *node, int eflags)
 {
 	ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
 	EState	   *estate = node->ss.ps.state;
+	Relation	rel = node->ss.ss_currentRelation;
 	PgFdwDirectModifyState *dmstate;
-	Index		rtindex;
+	Index		rtindex = node->resultRelInfo->ri_RangeTableIndex;
 	Oid			userid;
 	ForeignTable *table;
 	UserMapping *user;
@@ -2663,24 +2668,32 @@ postgresBeginDirectModify(ForeignScanState *node, int eflags)
 	if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
 		return;
 
+	/*
+	 * Open the foreign table using the RT index given in the ResultRelInfo if
+	 * the ScanState doesn't provide it.  If the plan becomes invalid as a
+	 * result of taking a lock in ExecOpenScanRelation(), do nothing, in which
+	 * case node->fdw_state remains NULL.
+	 */
+	if (rel == NULL)
+	{
+		Assert(fsplan->scan.scanrelid == 0);
+		rel = ExecOpenScanRelation(estate, rtindex, eflags);
+		if (unlikely(rel == NULL || !ExecPlanStillValid(estate)))
+			return;
+	}
+
 	/*
 	 * We'll save private state in node->fdw_state.
 	 */
 	dmstate = (PgFdwDirectModifyState *) palloc0(sizeof(PgFdwDirectModifyState));
 	node->fdw_state = (void *) dmstate;
+	dmstate->rel = rel;
 
 	/*
 	 * Identify which user to do the remote access as.  This should match what
 	 * ExecCheckPermissions() does.
 	 */
 	userid = OidIsValid(fsplan->checkAsUser) ? fsplan->checkAsUser : GetUserId();
-
-	/* Get info about foreign table. */
-	rtindex = node->resultRelInfo->ri_RangeTableIndex;
-	if (fsplan->scan.scanrelid == 0)
-		dmstate->rel = ExecOpenScanRelation(estate, rtindex, eflags);
-	else
-		dmstate->rel = node->ss.ss_currentRelation;
 	table = GetForeignTable(RelationGetRelid(dmstate->rel));
 	user = GetUserMapping(userid, table->serverid);
 
@@ -2811,7 +2824,10 @@ postgresEndDirectModify(ForeignScanState *node)
 {
 	PgFdwDirectModifyState *dmstate = (PgFdwDirectModifyState *) node->fdw_state;
 
-	/* if dmstate is NULL, we are in EXPLAIN; nothing to do */
+	/*
+	 * Nothing to do if dmstate is NULL, either because we are in EXPLAIN or
+	 * dmstate wasn't initialized due to aborted plan initialization.
+	 */
 	if (dmstate == NULL)
 		return;
 
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index a83ea07db1..a7643360a7 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -507,7 +507,8 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 	}
 
 	/* run it (if needed) and produce output */
-	ExplainOnePlan(plan, NULL, into, es, queryString, params, queryEnv,
+	ExplainOnePlan(plan, NULL, NULL, -1, into, es, queryString, params,
+				   queryEnv,
 				   &planduration, (es->buffers ? &bufusage : NULL),
 				   es->memory ? &mem_counters : NULL);
 }
@@ -616,6 +617,7 @@ ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es,
  */
 void
 ExplainOnePlan(PlannedStmt *plannedstmt, CachedPlan *cplan,
+			   CachedPlanSource *plansource, int query_index,
 			   IntoClause *into, ExplainState *es,
 			   const char *queryString, ParamListInfo params,
 			   QueryEnvironment *queryEnv, const instr_time *planduration,
@@ -686,8 +688,8 @@ ExplainOnePlan(PlannedStmt *plannedstmt, CachedPlan *cplan,
 	if (into)
 		eflags |= GetIntoRelEFlags(into);
 
-	/* call ExecutorStart to prepare the plan for execution */
-	ExecutorStart(queryDesc, eflags);
+	/* Call ExecutorStartExt to prepare the plan for execution. */
+	ExecutorStartExt(queryDesc, eflags, plansource, query_index);
 
 	/* Execute the plan for statistics if asked for */
 	if (es->analyze)
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index 4f6acf6719..4b1503c05e 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -107,6 +107,7 @@ PerformCursorOpen(ParseState *pstate, DeclareCursorStmt *cstmt, ParamListInfo pa
 					  queryString,
 					  CMDTAG_SELECT,	/* cursor's query is always a SELECT */
 					  list_make1(plan),
+					  NULL,
 					  NULL);
 
 	/*----------
diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index 311b9ebd5b..4cd79a6e3a 100644
--- a/src/backend/commands/prepare.c
+++ b/src/backend/commands/prepare.c
@@ -202,7 +202,8 @@ ExecuteQuery(ParseState *pstate,
 					  query_string,
 					  entry->plansource->commandTag,
 					  plan_list,
-					  cplan);
+					  cplan,
+					  entry->plansource);
 
 	/*
 	 * For CREATE TABLE ... AS EXECUTE, we must verify that the prepared
@@ -583,6 +584,7 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into, ExplainState *es,
 	MemoryContextCounters mem_counters;
 	MemoryContext planner_ctx = NULL;
 	MemoryContext saved_ctx = NULL;
+	int			i = 0;
 
 	if (es->memory)
 	{
@@ -655,8 +657,8 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into, ExplainState *es,
 		PlannedStmt *pstmt = lfirst_node(PlannedStmt, p);
 
 		if (pstmt->commandType != CMD_UTILITY)
-			ExplainOnePlan(pstmt, cplan, into, es, query_string, paramLI,
-						   queryEnv,
+			ExplainOnePlan(pstmt, cplan, entry->plansource, i,
+						   into, es, query_string, paramLI, queryEnv,
 						   &planduration, (es->buffers ? &bufusage : NULL),
 						   es->memory ? &mem_counters : NULL);
 		else
@@ -668,6 +670,8 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into, ExplainState *es,
 		/* Separate plans with an appropriate separator */
 		if (lnext(plan_list, p) != NULL)
 			ExplainSeparatePlans(es);
+
+		i++;
 	}
 
 	if (estate)
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 170360edda..91e4b821a0 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -5119,6 +5119,20 @@ AfterTriggerEndQuery(EState *estate)
 	afterTriggers.query_depth--;
 }
 
+/* ----------
+ * AfterTriggerAbortQuery()
+ *
+ * Called by ExecutorEnd() if the query execution was aborted due to the
+ * plan becoming invalid during initialization.
+ * ----------
+ */
+void
+AfterTriggerAbortQuery(void)
+{
+	/* Revert the actions of AfterTriggerBeginQuery(). */
+	afterTriggers.query_depth--;
+}
+
 
 /*
  * AfterTriggerFreeQuery
diff --git a/src/backend/executor/README b/src/backend/executor/README
index 642d63be61..e583df5be0 100644
--- a/src/backend/executor/README
+++ b/src/backend/executor/README
@@ -280,6 +280,28 @@ are typically reset to empty once per tuple.  Per-tuple contexts are usually
 associated with ExprContexts, and commonly each PlanState node has its own
 ExprContext to evaluate its qual and targetlist expressions in.
 
+Relation Locking
+----------------
+
+Typically, when the executor initializes a plan tree for execution, it doesn't
+lock non-index relations if the plan tree is freshly generated and not derived
+from a CachedPlan. This is because such locks have already been established
+during the query's parsing, rewriting, and planning phases. However, with a
+cached plan tree, some relations may remain unlocked. The function
+AcquireExecutorLocks() only locks unprunable relations in the plan, deferring
+the locking of prunable ones to executor initialization. This avoids
+unnecessary locking of relations that will be pruned during "initial" runtime
+pruning in the ExecInitNode() routine of nodes containing the pruning info.
+
+This approach creates a window where a cached plan tree with child tables
+could become outdated if another backend modifies these tables before
+ExecInitNode() locks them. As a result, the executor has the added duty to
+verify the plan tree's validity whenever it locks a child table after
+execution-initialization-pruning. This validation is done by checking the
+CachedPlan.is_valid attribute. If the plan tree is outdated (is_valid=false),
+the executor halts further initialization, cleans up the partially initialized
+PlanState tree, and retries execution after creating a new transient
+CachedPlan.
 
 Query Processing Control Flow
 -----------------------------
@@ -288,7 +310,7 @@ This is a sketch of control flow for full query processing:
 
 	CreateQueryDesc
 
-	ExecutorStart
+	ExecutorStart or ExecutorStartExt
 		CreateExecutorState
 			creates per-query context
 		switch to per-query context to run ExecInitNode
@@ -316,7 +338,13 @@ This is a sketch of control flow for full query processing:
 
 	FreeQueryDesc
 
-Per above comments, it's not really critical for ExecEndNode to free any
+As mentioned in the "Relation Locking" section, if the plan tree is found to
+be stale during one of the recursive calls of ExecInitNode() after taking a
+lock on a child table, the control is immmediately returned to
+ExecutorStartExt(), which will create a new plan tree and perform the
+steps starting from CreateExecutorState() again.
+
+Per above comments, it's not really critical for ExecEndPlan to free any
 memory; it'll all go away in FreeExecutorState anyway.  However, we do need to
 be careful to close relations, drop buffer pins, etc, so we do need to scan
 the plan state tree to find these sorts of resources.
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 0f6dbd1e2b..92e0c9af9e 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -58,6 +58,7 @@
 #include "utils/backend_status.h"
 #include "utils/lsyscache.h"
 #include "utils/partcache.h"
+#include "utils/plancache.h"
 #include "utils/rls.h"
 #include "utils/snapmgr.h"
 
@@ -133,6 +134,52 @@ ExecutorStart(QueryDesc *queryDesc, int eflags)
 		standard_ExecutorStart(queryDesc, eflags);
 }
 
+/*
+ * A variant of ExecutorStart() that handles cleanup and replanning if the
+ * input CachedPlan becomes invalid due to locks being taken during
+ * ExecutorStartInternal().  If that happens, a new CachedPlan is created
+ * only for the at the index 'query_index' in plansource->query_list, which
+ * is released separately from the original CachedPlan.
+ */
+void
+ExecutorStartExt(QueryDesc *queryDesc, int eflags,
+				 CachedPlanSource *plansource,
+				 int query_index)
+{
+	if (queryDesc->cplan == NULL)
+		ExecutorStart(queryDesc, eflags);
+	else
+	{
+		while (1)
+		{
+			ExecutorStart(queryDesc, eflags);
+			if (!CachedPlanStillValid(queryDesc->cplan))
+			{
+				CachedPlan *cplan_new;
+
+				/*
+				 * Mark execution as aborted to ensure that AFTER trigger
+				 * state is properly reset.
+				 */
+				queryDesc->estate->es_aborted = true;
+
+				ExecutorEnd(queryDesc);
+
+				cplan_new = GetSingleCachedPlan(plansource, query_index,
+												queryDesc->params,
+												queryDesc->queryEnv);
+				Assert(list_length(cplan_new->stmt_list) == 1);
+				queryDesc->cplan = cplan_new;
+				queryDesc->release_cplan = true;
+				queryDesc->plannedstmt = linitial_node(PlannedStmt,
+												   cplan_new->stmt_list);
+			}
+			else
+				break;
+		}
+	}
+}
+
 void
 standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
 {
@@ -316,6 +363,7 @@ standard_ExecutorRun(QueryDesc *queryDesc,
 	estate = queryDesc->estate;
 
 	Assert(estate != NULL);
+	Assert(!estate->es_aborted);
 	Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));
 
 	/* caller must ensure the query's snapshot is active */
@@ -422,8 +470,11 @@ standard_ExecutorFinish(QueryDesc *queryDesc)
 	Assert(estate != NULL);
 	Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));
 
-	/* This should be run once and only once per Executor instance */
-	Assert(!estate->es_finished);
+	/*
+	 * This should be run once and only once per Executor instance and never
+	 * if the execution was aborted.
+	 */
+	Assert(!estate->es_finished && !estate->es_aborted);
 
 	/* Switch into per-query memory context */
 	oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
@@ -482,11 +533,10 @@ standard_ExecutorEnd(QueryDesc *queryDesc)
 	Assert(estate != NULL);
 
 	/*
-	 * Check that ExecutorFinish was called, unless in EXPLAIN-only mode. This
-	 * Assert is needed because ExecutorFinish is new as of 9.1, and callers
-	 * might forget to call it.
+	 * Check that ExecutorFinish was called, unless in EXPLAIN-only mode or if
+	 * execution was aborted.
 	 */
-	Assert(estate->es_finished ||
+	Assert(estate->es_finished || estate->es_aborted ||
 		   (estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));
 
 	/*
@@ -500,6 +550,14 @@ standard_ExecutorEnd(QueryDesc *queryDesc)
 	UnregisterSnapshot(estate->es_snapshot);
 	UnregisterSnapshot(estate->es_crosscheck_snapshot);
 
+	/*
+	 * Reset AFTER trigger module if the query execution was aborted.
+	 */
+	if (estate->es_aborted &&
+		!(estate->es_top_eflags &
+		  (EXEC_FLAG_SKIP_TRIGGERS | EXEC_FLAG_EXPLAIN_ONLY)))
+		AfterTriggerAbortQuery();
+
 	/*
 	 * Must switch out of context before destroying it
 	 */
@@ -832,7 +890,6 @@ ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
 		PreventCommandIfParallelMode(CreateCommandName((Node *) plannedstmt));
 }
 
-
 /* ----------------------------------------------------------------
  *		InitPlan
  *
@@ -897,6 +954,9 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 				case ROW_MARK_KEYSHARE:
 				case ROW_MARK_REFERENCE:
 					relation = ExecGetRangeTableRelation(estate, rc->rti);
+					if (unlikely(relation == NULL ||
+								 !ExecPlanStillValid(estate)))
+						return;
 					break;
 				case ROW_MARK_COPY:
 					/* no physical table access is required */
@@ -967,6 +1027,8 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 
 		estate->es_subplanstates = lappend(estate->es_subplanstates,
 										   subplanstate);
+		if (unlikely(!ExecPlanStillValid(estate)))
+			return;
 
 		i++;
 	}
@@ -977,6 +1039,8 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	 * processing tuples.
 	 */
 	planstate = ExecInitNode(plan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return;
 
 	/*
 	 * Get the tuple descriptor describing the type of tuples to return.
@@ -2858,6 +2922,7 @@ EvalPlanQualStart(EPQState *epqstate, Plan *planTree)
 	rcestate->es_rowmarks = parentestate->es_rowmarks;
 	rcestate->es_rteperminfos = parentestate->es_rteperminfos;
 	rcestate->es_plannedstmt = parentestate->es_plannedstmt;
+	rcestate->es_cachedplan = parentestate->es_cachedplan;
 	rcestate->es_junkFilter = parentestate->es_junkFilter;
 	rcestate->es_output_cid = parentestate->es_output_cid;
 	rcestate->es_queryEnv = parentestate->es_queryEnv;
@@ -2936,6 +3001,14 @@ EvalPlanQualStart(EPQState *epqstate, Plan *planTree)
 		subplanstate = ExecInitNode(subplan, rcestate, 0);
 		rcestate->es_subplanstates = lappend(rcestate->es_subplanstates,
 											 subplanstate);
+
+		/*
+		 * All necessary locks should have been taken when initializing the
+		 * parent's copy of subplanstate, so the CachedPlan, if any, should
+		 * not have become invalid during the above ExecInitNode().
+		 */
+		if (!ExecPlanStillValid(rcestate))
+			elog(ERROR, "unexpected failure to initialize subplan in EvalPlanQualStart()");
 	}
 
 	/*
@@ -2977,6 +3050,10 @@ EvalPlanQualStart(EPQState *epqstate, Plan *planTree)
 	 */
 	epqstate->recheckplanstate = ExecInitNode(planTree, rcestate, 0);
 
+	/* See the comment above. */
+	if (!ExecPlanStillValid(rcestate))
+		elog(ERROR, "unexpected failure to initialize main plantree in EvalPlanQualStart()");
+
 	MemoryContextSwitchTo(oldcontext);
 }
 
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 03b48e12b4..2017433c64 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -1263,9 +1263,7 @@ ExecParallelGetQueryDesc(shm_toc *toc, DestReceiver *receiver,
 	 * if it should take locks on certain relations, but paraller workers
 	 * always take locks anyway.
 	 */
-	return CreateQueryDesc(pstmt,
-						   NULL,
-						   queryString,
+	return CreateQueryDesc(pstmt, NULL, queryString,
 						   GetActiveSnapshot(), InvalidSnapshot,
 						   receiver, paramLI, NULL, instrument_options);
 }
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7651886229..38cd97b59c 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1794,6 +1794,9 @@ adjust_partition_colnos_using_map(List *colnos, AttrMap *attrMap)
  * If subplans are indeed pruned, subplan_map arrays contained in the returned
  * PartitionPruneState are re-sequenced to not count those, though only if the
  * maps will be needed for subsequent execution pruning passes.
+ *
+ * Returns NULL if the plan has become invalid after taking the locks to
+ * create the PartitionPruneState in CreatePartitionPruneState().
  */
 PartitionPruneState *
 ExecInitPartitionPruning(PlanState *planstate,
@@ -1809,6 +1812,8 @@ ExecInitPartitionPruning(PlanState *planstate,
 
 	/* Create the working data structure for pruning */
 	prunestate = CreatePartitionPruneState(planstate, pruneinfo);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	/*
 	 * Perform an initial partition prune pass, if required.
@@ -1860,6 +1865,9 @@ ExecInitPartitionPruning(PlanState *planstate,
  * stored in each PartitionedRelPruningData can be re-used each time we
  * re-evaluate which partitions match the pruning steps provided in each
  * PartitionedRelPruneInfo.
+ *
+ * Returns NULL if the plan has become invalid after taking a lock to create
+ * a PartitionedRelPruningData.
  */
 static PartitionPruneState *
 CreatePartitionPruneState(PlanState *planstate, PartitionPruneInfo *pruneinfo)
@@ -1935,6 +1943,8 @@ CreatePartitionPruneState(PlanState *planstate, PartitionPruneInfo *pruneinfo)
 			 * duration of this executor run.
 			 */
 			partrel = ExecGetRangeTableRelation(estate, pinfo->rtindex);
+			if (unlikely(partrel == NULL || !ExecPlanStillValid(estate)))
+				return NULL;
 			partkey = RelationGetPartitionKey(partrel);
 			partdesc = PartitionDirectoryLookup(estate->es_partition_directory,
 												partrel);
diff --git a/src/backend/executor/execProcnode.c b/src/backend/executor/execProcnode.c
index 34f28dfece..7689d34dd0 100644
--- a/src/backend/executor/execProcnode.c
+++ b/src/backend/executor/execProcnode.c
@@ -136,6 +136,10 @@ static bool ExecShutdownNode_walker(PlanState *node, void *context);
  *		  'eflags' is a bitwise OR of flag bits described in executor.h
  *
  *		Returns a PlanState node corresponding to the given Plan node.
+ *
+ *		Callers should check upon returning that ExecPlanStillValid(estate)
+ *		returns true before continuing further with its processing, because the
+ *		returned PlanState might be only partially valid otherwise.
  * ------------------------------------------------------------------------
  */
 PlanState *
@@ -388,6 +392,9 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
 			break;
 	}
 
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return result;
+
 	ExecSetExecProcNode(result, result->ExecProcNode);
 
 	/*
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index 6dfd5a26b7..39b388e6b4 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -146,6 +146,7 @@ CreateExecutorState(void)
 	estate->es_top_eflags = 0;
 	estate->es_instrument = 0;
 	estate->es_finished = false;
+	estate->es_aborted = false;
 
 	estate->es_exprcontexts = NIL;
 
@@ -691,6 +692,8 @@ ExecRelationIsTargetRelation(EState *estate, Index scanrelid)
  *
  *		Open the heap relation to be scanned by a base-level scan plan node.
  *		This should be called during the node's ExecInit routine.
+ *
+ *		NULL is returned if the relation is found to have been dropped.
  * ----------------------------------------------------------------
  */
 Relation
@@ -700,6 +703,8 @@ ExecOpenScanRelation(EState *estate, Index scanrelid, int eflags)
 
 	/* Open the relation. */
 	rel = ExecGetRangeTableRelation(estate, scanrelid);
+	if (unlikely(rel == NULL || !ExecPlanStillValid(estate)))
+		return rel;
 
 	/*
 	 * Complain if we're attempting a scan of an unscannable relation, except
@@ -717,6 +722,26 @@ ExecOpenScanRelation(EState *estate, Index scanrelid, int eflags)
 	return rel;
 }
 
+/* ----------------------------------------------------------------
+ *		ExecOpenScanIndexRelation
+ *
+ *		Open the index relation to be scanned by an index scan plan node.
+ *		This should be called during the node's ExecInit routine.
+ * ----------------------------------------------------------------
+ */
+Relation
+ExecOpenScanIndexRelation(EState *estate, Oid indexid, int lockmode)
+{
+	Relation	rel;
+
+	/* Open the index. */
+	rel = index_open(indexid, lockmode);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		elog(DEBUG2, "CachedPlan invalidated on locking index %u", indexid);
+
+	return rel;
+}
+
 /*
  * ExecInitRangeTable
  *		Set up executor's range-table-related data
@@ -776,8 +801,12 @@ ExecShouldLockRelation(EState *estate, Index rtindex)
  * ExecGetRangeTableRelation
  *		Open the Relation for a range table entry, if not already done
  *
- * The Relations will be closed again in ExecEndPlan().
+ * The Relations will be closed in ExecEndPlan().
+ *
+ * The returned value may be NULL if the relation is a prunable relation
+ * that has not been locked and may have been concurrently dropped.
  */
+
 Relation
 ExecGetRangeTableRelation(EState *estate, Index rti)
 {
@@ -820,8 +849,14 @@ ExecGetRangeTableRelation(EState *estate, Index rti)
 			 * that of a prunable relation and we're running a cached generic
 			 * plan.  AcquireExecutorLocks() of plancache.c would have locked
 			 * only the unprunable relations in the plan tree.
+			 *
+			 * Note that we use try_table_open() here, because without a lock
+			 * held on the relation, it may have disappeared from under us.
 			 */
-			rel = table_open(rte->relid, rte->rellockmode);
+			rel = try_table_open(rte->relid, rte->rellockmode);
+			if (unlikely(!ExecPlanStillValid(estate)))
+				elog(DEBUG2, "CachedPlan invalidated on locking relation %u",
+					 rte->relid);
 		}
 
 		estate->es_relations[rti - 1] = rel;
@@ -845,6 +880,9 @@ ExecInitResultRelation(EState *estate, ResultRelInfo *resultRelInfo,
 	Relation	resultRelationDesc;
 
 	resultRelationDesc = ExecGetRangeTableRelation(estate, rti);
+	if (unlikely(resultRelationDesc == NULL ||
+				 !ExecPlanStillValid(estate)))
+		return;
 	InitResultRelInfo(resultRelInfo,
 					  resultRelationDesc,
 					  rti,
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 0dfba5ca16..8c40d8c520 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3303,6 +3303,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		eflags &= ~EXEC_FLAG_REWIND;
 	outerPlan = outerPlan(node);
 	outerPlanState(aggstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return aggstate;
 
 	/*
 	 * initialize source tuple type.
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 86d75b1a7e..3c82a1ceab 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -147,6 +147,8 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 											  list_length(node->appendplans),
 											  node->part_prune_info,
 											  &validsubplans);
+		if (!ExecPlanStillValid(estate))
+			return appendstate;
 		appendstate->as_prune_state = prunestate;
 		nplans = bms_num_members(validsubplans);
 
@@ -185,8 +187,10 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 	appendstate->ps.resultopsset = true;
 	appendstate->ps.resultopsfixed = false;
 
-	appendplanstates = (PlanState **) palloc(nplans *
-											 sizeof(PlanState *));
+	appendplanstates = (PlanState **) palloc0(nplans *
+											  sizeof(PlanState *));
+	appendstate->appendplans = appendplanstates;
+	appendstate->as_nplans = nplans;
 
 	/*
 	 * call ExecInitNode on each of the valid plans to be executed and save
@@ -221,11 +225,11 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 			firstvalid = j;
 
 		appendplanstates[j++] = ExecInitNode(initNode, estate, eflags);
+		if (unlikely(!ExecPlanStillValid(estate)))
+			return appendstate;
 	}
 
 	appendstate->as_first_partial_plan = firstvalid;
-	appendstate->appendplans = appendplanstates;
-	appendstate->as_nplans = nplans;
 
 	/* Initialize async state */
 	appendstate->as_asyncplans = asyncplans;
diff --git a/src/backend/executor/nodeBitmapAnd.c b/src/backend/executor/nodeBitmapAnd.c
index ae391222bf..168c440692 100644
--- a/src/backend/executor/nodeBitmapAnd.c
+++ b/src/backend/executor/nodeBitmapAnd.c
@@ -89,6 +89,8 @@ ExecInitBitmapAnd(BitmapAnd *node, EState *estate, int eflags)
 	{
 		initNode = (Plan *) lfirst(l);
 		bitmapplanstates[i] = ExecInitNode(initNode, estate, eflags);
+		if (unlikely(!ExecPlanStillValid(estate)))
+			return bitmapandstate;
 		i++;
 	}
 
diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c
index 19f18ab817..b13cae1cbb 100644
--- a/src/backend/executor/nodeBitmapHeapscan.c
+++ b/src/backend/executor/nodeBitmapHeapscan.c
@@ -754,11 +754,15 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (unlikely(currentRelation == NULL || !ExecPlanStillValid(estate)))
+		return scanstate;
 
 	/*
 	 * initialize child nodes
 	 */
 	outerPlanState(scanstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return scanstate;
 
 	/*
 	 * get the scan type from the relation descriptor.
diff --git a/src/backend/executor/nodeBitmapIndexscan.c b/src/backend/executor/nodeBitmapIndexscan.c
index 4669e8d0ce..f04a53e9be 100644
--- a/src/backend/executor/nodeBitmapIndexscan.c
+++ b/src/backend/executor/nodeBitmapIndexscan.c
@@ -252,7 +252,11 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate, int eflags)
 
 	/* Open the index relation. */
 	lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
-	indexstate->biss_RelationDesc = index_open(node->indexid, lockmode);
+	indexstate->biss_RelationDesc = ExecOpenScanIndexRelation(estate,
+															  node->indexid,
+															  lockmode);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return indexstate;
 
 	/*
 	 * Initialize index-specific scan state
diff --git a/src/backend/executor/nodeBitmapOr.c b/src/backend/executor/nodeBitmapOr.c
index de439235d2..980b68dd82 100644
--- a/src/backend/executor/nodeBitmapOr.c
+++ b/src/backend/executor/nodeBitmapOr.c
@@ -90,6 +90,8 @@ ExecInitBitmapOr(BitmapOr *node, EState *estate, int eflags)
 	{
 		initNode = (Plan *) lfirst(l);
 		bitmapplanstates[i] = ExecInitNode(initNode, estate, eflags);
+		if (unlikely(!ExecPlanStillValid(estate)))
+			return bitmaporstate;
 		i++;
 	}
 
diff --git a/src/backend/executor/nodeCustom.c b/src/backend/executor/nodeCustom.c
index e559cd2346..2a7c5dccd8 100644
--- a/src/backend/executor/nodeCustom.c
+++ b/src/backend/executor/nodeCustom.c
@@ -58,6 +58,8 @@ ExecInitCustomScan(CustomScan *cscan, EState *estate, int eflags)
 	if (scanrelid > 0)
 	{
 		scan_rel = ExecOpenScanRelation(estate, scanrelid, eflags);
+		if (unlikely(scan_rel == NULL || !ExecPlanStillValid(estate)))
+			return css;
 		css->ss.ss_currentRelation = scan_rel;
 	}
 
diff --git a/src/backend/executor/nodeForeignscan.c b/src/backend/executor/nodeForeignscan.c
index 1357ccf3c9..90d5878ae3 100644
--- a/src/backend/executor/nodeForeignscan.c
+++ b/src/backend/executor/nodeForeignscan.c
@@ -172,6 +172,8 @@ ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
 	if (scanrelid > 0)
 	{
 		currentRelation = ExecOpenScanRelation(estate, scanrelid, eflags);
+		if (unlikely(currentRelation == NULL || !ExecPlanStillValid(estate)))
+			return scanstate;
 		scanstate->ss.ss_currentRelation = currentRelation;
 		fdwroutine = GetFdwRoutineForRelation(currentRelation, true);
 	}
@@ -263,6 +265,8 @@ ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
 	if (outerPlan(node))
 		outerPlanState(scanstate) =
 			ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return scanstate;
 
 	/*
 	 * Tell the FDW to initialize the scan.
diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c
index cae5ea1f92..67548aa7ba 100644
--- a/src/backend/executor/nodeGather.c
+++ b/src/backend/executor/nodeGather.c
@@ -84,6 +84,8 @@ ExecInitGather(Gather *node, EState *estate, int eflags)
 	 */
 	outerNode = outerPlan(node);
 	outerPlanState(gatherstate) = ExecInitNode(outerNode, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return gatherstate;
 	tupDesc = ExecGetResultType(outerPlanState(gatherstate));
 
 	/*
diff --git a/src/backend/executor/nodeGatherMerge.c b/src/backend/executor/nodeGatherMerge.c
index b36cd89e7d..cf0e074359 100644
--- a/src/backend/executor/nodeGatherMerge.c
+++ b/src/backend/executor/nodeGatherMerge.c
@@ -103,6 +103,8 @@ ExecInitGatherMerge(GatherMerge *node, EState *estate, int eflags)
 	 */
 	outerNode = outerPlan(node);
 	outerPlanState(gm_state) = ExecInitNode(outerNode, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return gm_state;
 
 	/*
 	 * Leader may access ExecProcNode result directly (if
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 807429e504..6d0fd9e7b4 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -184,6 +184,8 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(grpstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return grpstate;
 
 	/*
 	 * Initialize scan slot and type.
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index a913d5b50c..e71d131d18 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -396,6 +396,8 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(hashstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return hashstate;
 
 	/*
 	 * initialize our result slot and type. No need to build projection
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 901c9e9be7..3c870de1c5 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -758,8 +758,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	hashNode = (Hash *) innerPlan(node);
 
 	outerPlanState(hjstate) = ExecInitNode(outerNode, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return hjstate;
 	outerDesc = ExecGetResultType(outerPlanState(hjstate));
 	innerPlanState(hjstate) = ExecInitNode((Plan *) hashNode, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return hjstate;
 	innerDesc = ExecGetResultType(innerPlanState(hjstate));
 
 	/*
diff --git a/src/backend/executor/nodeIncrementalSort.c b/src/backend/executor/nodeIncrementalSort.c
index 010bcfafa8..af723ea755 100644
--- a/src/backend/executor/nodeIncrementalSort.c
+++ b/src/backend/executor/nodeIncrementalSort.c
@@ -1040,6 +1040,8 @@ ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags)
 	 * nodes may be able to do something more useful.
 	 */
 	outerPlanState(incrsortstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return incrsortstate;
 
 	/*
 	 * Initialize scan slot and type.
diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c
index 481d479760..0fba8f7d5a 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -531,6 +531,8 @@ ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (unlikely(currentRelation == NULL || !ExecPlanStillValid(estate)))
+		return indexstate;
 
 	indexstate->ss.ss_currentRelation = currentRelation;
 	indexstate->ss.ss_currentScanDesc = NULL;	/* no heap scan here */
@@ -583,9 +585,12 @@ ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
 
 	/* Open the index relation. */
 	lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
-	indexRelation = index_open(node->indexid, lockmode);
+	indexRelation = ExecOpenScanIndexRelation(estate, node->indexid, lockmode);
 	indexstate->ioss_RelationDesc = indexRelation;
 
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return indexstate;
+
 	/*
 	 * Initialize index-specific scan state
 	 */
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index a8172d8b82..db28aeb3d6 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -907,6 +907,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (unlikely(currentRelation == NULL || !ExecPlanStillValid(estate)))
+		return indexstate;
 
 	indexstate->ss.ss_currentRelation = currentRelation;
 	indexstate->ss.ss_currentScanDesc = NULL;	/* no heap scan here */
@@ -951,7 +953,11 @@ ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
 
 	/* Open the index relation. */
 	lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
-	indexstate->iss_RelationDesc = index_open(node->indexid, lockmode);
+	indexstate->iss_RelationDesc = ExecOpenScanIndexRelation(estate,
+															 node->indexid,
+															 lockmode);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return indexstate;
 
 	/*
 	 * Initialize index-specific scan state
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c
index eb7b6e52be..369c904577 100644
--- a/src/backend/executor/nodeLimit.c
+++ b/src/backend/executor/nodeLimit.c
@@ -475,6 +475,8 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
 	 */
 	outerPlan = outerPlan(node);
 	outerPlanState(limitstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return limitstate;
 
 	/*
 	 * initialize child expressions
diff --git a/src/backend/executor/nodeLockRows.c b/src/backend/executor/nodeLockRows.c
index 0d3489195b..9077858413 100644
--- a/src/backend/executor/nodeLockRows.c
+++ b/src/backend/executor/nodeLockRows.c
@@ -322,6 +322,8 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 	 * then initialize outer plan
 	 */
 	outerPlanState(lrstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return lrstate;
 
 	/* node returns unmodified slots from the outer plan */
 	lrstate->ps.resultopsset = true;
diff --git a/src/backend/executor/nodeMaterial.c b/src/backend/executor/nodeMaterial.c
index 883e3f3933..972962d44d 100644
--- a/src/backend/executor/nodeMaterial.c
+++ b/src/backend/executor/nodeMaterial.c
@@ -214,6 +214,8 @@ ExecInitMaterial(Material *node, EState *estate, int eflags)
 
 	outerPlan = outerPlan(node);
 	outerPlanState(matstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return matstate;
 
 	/*
 	 * Initialize result type and slot. No need to initialize projection info
diff --git a/src/backend/executor/nodeMemoize.c b/src/backend/executor/nodeMemoize.c
index 690dee1daa..6aaab743b5 100644
--- a/src/backend/executor/nodeMemoize.c
+++ b/src/backend/executor/nodeMemoize.c
@@ -973,6 +973,8 @@ ExecInitMemoize(Memoize *node, EState *estate, int eflags)
 
 	outerNode = outerPlan(node);
 	outerPlanState(mstate) = ExecInitNode(outerNode, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return mstate;
 
 	/*
 	 * Initialize return slot and type. No need to initialize projection info
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 3236444cf1..a82f0a71a0 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -95,6 +95,8 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 											  list_length(node->mergeplans),
 											  node->part_prune_info,
 											  &validsubplans);
+		if (!ExecPlanStillValid(estate))
+			return mergestate;
 		mergestate->ms_prune_state = prunestate;
 		nplans = bms_num_members(validsubplans);
 
@@ -120,7 +122,7 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		mergestate->ms_prune_state = NULL;
 	}
 
-	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
+	mergeplanstates = (PlanState **) palloc0(nplans * sizeof(PlanState *));
 	mergestate->mergeplans = mergeplanstates;
 	mergestate->ms_nplans = nplans;
 
@@ -151,6 +153,8 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		Plan	   *initNode = (Plan *) list_nth(node->mergeplans, i);
 
 		mergeplanstates[j++] = ExecInitNode(initNode, estate, eflags);
+		if (unlikely(!ExecPlanStillValid(estate)))
+			return mergestate;
 	}
 
 	mergestate->ps.ps_ProjInfo = NULL;
diff --git a/src/backend/executor/nodeMergejoin.c b/src/backend/executor/nodeMergejoin.c
index 926e631d88..53cb1ff207 100644
--- a/src/backend/executor/nodeMergejoin.c
+++ b/src/backend/executor/nodeMergejoin.c
@@ -1490,11 +1490,15 @@ ExecInitMergeJoin(MergeJoin *node, EState *estate, int eflags)
 	mergestate->mj_SkipMarkRestore = node->skip_mark_restore;
 
 	outerPlanState(mergestate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return mergestate;
 	outerDesc = ExecGetResultType(outerPlanState(mergestate));
 	innerPlanState(mergestate) = ExecInitNode(innerPlan(node), estate,
 											  mergestate->mj_SkipMarkRestore ?
 											  eflags :
 											  (eflags | EXEC_FLAG_MARK));
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return mergestate;
 	innerDesc = ExecGetResultType(innerPlanState(mergestate));
 
 	/*
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 9e56f9c36c..8debfbd3ec 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -4277,6 +4277,13 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 							   linitial_int(node->resultRelations));
 	}
 
+	/*
+	 * ExecInitResultRelation() may have returned without initializing
+	 * rootResultRelInfo if the plan got invalidated, so check.
+	 */
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return mtstate;
+
 	/* set up epqstate with dummy subplan data for the moment */
 	EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, NIL,
 					 node->epqParam, node->resultRelations);
@@ -4309,6 +4316,10 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		{
 			ExecInitResultRelation(estate, resultRelInfo, resultRelation);
 
+			/* See the comment above. */
+			if (unlikely(!ExecPlanStillValid(estate)))
+				return mtstate;
+
 			/*
 			 * For child result relations, store the root result relation
 			 * pointer.  We do so for the convenience of places that want to
@@ -4335,6 +4346,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	 * Now we may initialize the subplan.
 	 */
 	outerPlanState(mtstate) = ExecInitNode(subplan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return mtstate;
 
 	/*
 	 * Do additional per-result-relation initialization.
diff --git a/src/backend/executor/nodeNestloop.c b/src/backend/executor/nodeNestloop.c
index 01f3d56a3b..34eafbb6e0 100644
--- a/src/backend/executor/nodeNestloop.c
+++ b/src/backend/executor/nodeNestloop.c
@@ -294,11 +294,15 @@ ExecInitNestLoop(NestLoop *node, EState *estate, int eflags)
 	 * values.
 	 */
 	outerPlanState(nlstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return nlstate;
 	if (node->nestParams == NIL)
 		eflags |= EXEC_FLAG_REWIND;
 	else
 		eflags &= ~EXEC_FLAG_REWIND;
 	innerPlanState(nlstate) = ExecInitNode(innerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return nlstate;
 
 	/*
 	 * Initialize result slot, type and projection.
diff --git a/src/backend/executor/nodeProjectSet.c b/src/backend/executor/nodeProjectSet.c
index ca9a5e2ed2..f834499479 100644
--- a/src/backend/executor/nodeProjectSet.c
+++ b/src/backend/executor/nodeProjectSet.c
@@ -254,6 +254,8 @@ ExecInitProjectSet(ProjectSet *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(state) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return state;
 
 	/*
 	 * we don't use inner plan
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index 7680142c7b..5dd3285c41 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -244,7 +244,11 @@ ExecInitRecursiveUnion(RecursiveUnion *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(rustate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return rustate;
 	innerPlanState(rustate) = ExecInitNode(innerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return rustate;
 
 	/*
 	 * If hashing, precompute fmgr lookup data for inner loop, and create the
diff --git a/src/backend/executor/nodeResult.c b/src/backend/executor/nodeResult.c
index e3cfc9b772..7d7c2aa786 100644
--- a/src/backend/executor/nodeResult.c
+++ b/src/backend/executor/nodeResult.c
@@ -207,6 +207,8 @@ ExecInitResult(Result *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(resstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return resstate;
 
 	/*
 	 * we don't use inner plan
diff --git a/src/backend/executor/nodeSamplescan.c b/src/backend/executor/nodeSamplescan.c
index 6ab91001bc..3afdaeecd7 100644
--- a/src/backend/executor/nodeSamplescan.c
+++ b/src/backend/executor/nodeSamplescan.c
@@ -121,6 +121,9 @@ ExecInitSampleScan(SampleScan *node, EState *estate, int eflags)
 		ExecOpenScanRelation(estate,
 							 node->scan.scanrelid,
 							 eflags);
+	if (unlikely(scanstate->ss.ss_currentRelation == NULL ||
+				 !ExecPlanStillValid(estate)))
+		return scanstate;
 
 	/* we won't set up the HeapScanDesc till later */
 	scanstate->ss.ss_currentScanDesc = NULL;
diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c
index b052775e5b..f7fb64a4a2 100644
--- a/src/backend/executor/nodeSeqscan.c
+++ b/src/backend/executor/nodeSeqscan.c
@@ -153,6 +153,9 @@ ExecInitSeqScan(SeqScan *node, EState *estate, int eflags)
 		ExecOpenScanRelation(estate,
 							 node->scan.scanrelid,
 							 eflags);
+	if (unlikely(scanstate->ss.ss_currentRelation == NULL ||
+				 !ExecPlanStillValid(estate)))
+		return scanstate;
 
 	/* and create slot with the appropriate rowtype */
 	ExecInitScanTupleSlot(estate, &scanstate->ss,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index fe34b2134f..2231d8b82f 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -528,6 +528,8 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 	if (node->strategy == SETOP_HASHED)
 		eflags &= ~EXEC_FLAG_REWIND;
 	outerPlanState(setopstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return setopstate;
 	outerDesc = ExecGetResultType(outerPlanState(setopstate));
 
 	/*
diff --git a/src/backend/executor/nodeSort.c b/src/backend/executor/nodeSort.c
index af852464d0..fb76e4c01b 100644
--- a/src/backend/executor/nodeSort.c
+++ b/src/backend/executor/nodeSort.c
@@ -263,6 +263,8 @@ ExecInitSort(Sort *node, EState *estate, int eflags)
 	eflags &= ~(EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);
 
 	outerPlanState(sortstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return sortstate;
 
 	/*
 	 * Initialize scan slot and type.
diff --git a/src/backend/executor/nodeSubqueryscan.c b/src/backend/executor/nodeSubqueryscan.c
index 0b2612183a..b5b538fa91 100644
--- a/src/backend/executor/nodeSubqueryscan.c
+++ b/src/backend/executor/nodeSubqueryscan.c
@@ -124,6 +124,8 @@ ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
 	 * initialize subquery
 	 */
 	subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return subquerystate;
 
 	/*
 	 * Initialize scan slot and type (needed by ExecAssignScanProjectionInfo)
diff --git a/src/backend/executor/nodeTidrangescan.c b/src/backend/executor/nodeTidrangescan.c
index 702ee884d2..a76836d021 100644
--- a/src/backend/executor/nodeTidrangescan.c
+++ b/src/backend/executor/nodeTidrangescan.c
@@ -377,6 +377,8 @@ ExecInitTidRangeScan(TidRangeScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (unlikely(currentRelation == NULL || !ExecPlanStillValid(estate)))
+		return tidrangestate;
 
 	tidrangestate->ss.ss_currentRelation = currentRelation;
 	tidrangestate->ss.ss_currentScanDesc = NULL;	/* no table scan here */
diff --git a/src/backend/executor/nodeTidscan.c b/src/backend/executor/nodeTidscan.c
index f375951699..088babf572 100644
--- a/src/backend/executor/nodeTidscan.c
+++ b/src/backend/executor/nodeTidscan.c
@@ -522,6 +522,8 @@ ExecInitTidScan(TidScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (unlikely(currentRelation == NULL || !ExecPlanStillValid(estate)))
+		return tidstate;
 
 	tidstate->ss.ss_currentRelation = currentRelation;
 	tidstate->ss.ss_currentScanDesc = NULL; /* no heap scan here */
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index b82d0e9ad5..cb46b2d5d0 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -135,6 +135,8 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 	 * then initialize outer plan
 	 */
 	outerPlanState(uniquestate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return uniquestate;
 
 	/*
 	 * Initialize result slot and type. Unique nodes do no projections, so
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 561d7e731d..1b96f51fe8 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2464,6 +2464,8 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 	 */
 	outerPlan = outerPlan(node);
 	outerPlanState(winstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (unlikely(!ExecPlanStillValid(estate)))
+		return winstate;
 
 	/*
 	 * initialize source tuple type (which is also the tuple type that we'll
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 902793b02b..b754827013 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -70,7 +70,8 @@ static int	_SPI_execute_plan(SPIPlanPtr plan, const SPIExecuteOptions *options,
 static ParamListInfo _SPI_convert_params(int nargs, Oid *argtypes,
 										 Datum *Values, const char *Nulls);
 
-static int	_SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount);
+static int	_SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount,
+						CachedPlanSource *plansource, int query_index);
 
 static void _SPI_error_callback(void *arg);
 
@@ -1682,7 +1683,8 @@ SPI_cursor_open_internal(const char *name, SPIPlanPtr plan,
 					  query_string,
 					  plansource->commandTag,
 					  stmt_list,
-					  cplan);
+					  cplan,
+					  plansource);
 
 	/*
 	 * Set up options for portal.  Default SCROLL type is chosen the same way
@@ -2494,6 +2496,7 @@ _SPI_execute_plan(SPIPlanPtr plan, const SPIExecuteOptions *options,
 		CachedPlanSource *plansource = (CachedPlanSource *) lfirst(lc1);
 		List	   *stmt_list;
 		ListCell   *lc2;
+		int			i = 0;
 
 		spicallbackarg.query = plansource->query_string;
 
@@ -2691,8 +2694,9 @@ _SPI_execute_plan(SPIPlanPtr plan, const SPIExecuteOptions *options,
 										options->params,
 										_SPI_current->queryEnv,
 										0);
-				res = _SPI_pquery(qdesc, fire_triggers,
-								  canSetTag ? options->tcount : 0);
+
+				res = _SPI_pquery(qdesc, fire_triggers, canSetTag ? options->tcount : 0,
+								  plansource, i);
 				FreeQueryDesc(qdesc);
 			}
 			else
@@ -2789,6 +2793,8 @@ _SPI_execute_plan(SPIPlanPtr plan, const SPIExecuteOptions *options,
 				my_res = res;
 				goto fail;
 			}
+
+			i++;
 		}
 
 		/* Done with this plan, so release refcount */
@@ -2866,7 +2872,8 @@ _SPI_convert_params(int nargs, Oid *argtypes,
 }
 
 static int
-_SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount)
+_SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount,
+			CachedPlanSource *plansource, int query_index)
 {
 	int			operation = queryDesc->operation;
 	int			eflags;
@@ -2922,7 +2929,7 @@ _SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount)
 	else
 		eflags = EXEC_FLAG_SKIP_TRIGGERS;
 
-	ExecutorStart(queryDesc, eflags);
+	ExecutorStartExt(queryDesc, eflags, plansource, query_index);
 
 	ExecutorRun(queryDesc, ForwardScanDirection, tcount, true);
 
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 8bc6bea113..ccbc27b575 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1237,6 +1237,7 @@ exec_simple_query(const char *query_string)
 						  query_string,
 						  commandTag,
 						  plantree_list,
+						  NULL,
 						  NULL);
 
 		/*
@@ -2027,7 +2028,8 @@ exec_bind_message(StringInfo input_message)
 					  query_string,
 					  psrc->commandTag,
 					  cplan->stmt_list,
-					  cplan);
+					  cplan,
+					  psrc);
 
 	/* Done with the snapshot used for parameter I/O and parsing/planning */
 	if (snapshot_set)
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index 6e8f6b1b8f..d9ae60579b 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -19,6 +19,7 @@
 
 #include "access/xact.h"
 #include "commands/prepare.h"
+#include "executor/execdesc.h"
 #include "executor/tstoreReceiver.h"
 #include "miscadmin.h"
 #include "pg_trace.h"
@@ -37,6 +38,8 @@ Portal		ActivePortal = NULL;
 
 static void ProcessQuery(PlannedStmt *plan,
 						 CachedPlan *cplan,
+						 CachedPlanSource *plansource,
+						 int query_index,
 						 const char *sourceText,
 						 ParamListInfo params,
 						 QueryEnvironment *queryEnv,
@@ -80,6 +83,7 @@ CreateQueryDesc(PlannedStmt *plannedstmt,
 	qd->operation = plannedstmt->commandType;	/* operation */
 	qd->plannedstmt = plannedstmt;	/* plan */
 	qd->cplan = cplan;			/* CachedPlan supplying the plannedstmt */
+	qd->release_cplan = false;
 	qd->sourceText = sourceText;	/* query text */
 	qd->snapshot = RegisterSnapshot(snapshot);	/* snapshot */
 	/* RI check snapshot */
@@ -114,6 +118,13 @@ FreeQueryDesc(QueryDesc *qdesc)
 	UnregisterSnapshot(qdesc->snapshot);
 	UnregisterSnapshot(qdesc->crosscheck_snapshot);
 
+	/*
+	 * Release CachedPlan if requested.  The CachedPlan is not associated with
+	 * a ResourceOwner when release_cplan is true; see ExecutorStartExt().
+	 */
+	if (qdesc->release_cplan)
+		ReleaseCachedPlan(qdesc->cplan, NULL);
+
 	/* Only the QueryDesc itself need be freed */
 	pfree(qdesc);
 }
@@ -126,6 +137,8 @@ FreeQueryDesc(QueryDesc *qdesc)
  *
  *	plan: the plan tree for the query
  *	cplan: CachedPlan supplying the plan
+ *	plansource: CachedPlanSource supplying the cplan
+ *	query_index: index of the query in plansource->query_list
  *	sourceText: the source text of the query
  *	params: any parameters needed
  *	dest: where to send results
@@ -139,6 +152,8 @@ FreeQueryDesc(QueryDesc *qdesc)
 static void
 ProcessQuery(PlannedStmt *plan,
 			 CachedPlan *cplan,
+			 CachedPlanSource *plansource,
+			 int query_index,
 			 const char *sourceText,
 			 ParamListInfo params,
 			 QueryEnvironment *queryEnv,
@@ -157,7 +172,7 @@ ProcessQuery(PlannedStmt *plan,
 	/*
 	 * Call ExecutorStart to prepare the plan for execution
 	 */
-	ExecutorStart(queryDesc, 0);
+	ExecutorStartExt(queryDesc, 0, plansource, query_index);
 
 	/*
 	 * Run the plan to completion.
@@ -518,9 +533,12 @@ PortalStart(Portal portal, ParamListInfo params,
 					myeflags = eflags;
 
 				/*
-				 * Call ExecutorStart to prepare the plan for execution
+				 * ExecutorStartExt() to prepare the plan for execution.  If
+				 * the portal is using a cached plan, it  may get invalidated
+				 * during plan intialization, in which case a new one is
+				 * created and saved in the QueryDesc.
 				 */
-				ExecutorStart(queryDesc, myeflags);
+				ExecutorStartExt(queryDesc, myeflags, portal->plansource, 0);
 
 				/*
 				 * This tells PortalCleanup to shut down the executor
@@ -1201,6 +1219,7 @@ PortalRunMulti(Portal portal,
 {
 	bool		active_snapshot_set = false;
 	ListCell   *stmtlist_item;
+	int			i = 0;
 
 	/*
 	 * If the destination is DestRemoteExecute, change to DestNone.  The
@@ -1283,6 +1302,8 @@ PortalRunMulti(Portal portal,
 				/* statement can set tag string */
 				ProcessQuery(pstmt,
 							 portal->cplan,
+							 portal->plansource,
+							 i,
 							 portal->sourceText,
 							 portal->portalParams,
 							 portal->queryEnv,
@@ -1293,6 +1314,8 @@ PortalRunMulti(Portal portal,
 				/* stmt added by rewrite cannot set tag */
 				ProcessQuery(pstmt,
 							 portal->cplan,
+							 portal->plansource,
+							 i,
 							 portal->sourceText,
 							 portal->portalParams,
 							 portal->queryEnv,
@@ -1357,6 +1380,8 @@ PortalRunMulti(Portal portal,
 		 */
 		if (lnext(portal->stmts, stmtlist_item) != NULL)
 			CommandCounterIncrement();
+
+		i++;
 	}
 
 	/* Pop the snapshot if we pushed one. */
diff --git a/src/backend/utils/cache/plancache.c b/src/backend/utils/cache/plancache.c
index 6d2e385fe8..6ae05175c6 100644
--- a/src/backend/utils/cache/plancache.c
+++ b/src/backend/utils/cache/plancache.c
@@ -1279,6 +1279,56 @@ GetCachedPlan(CachedPlanSource *plansource, ParamListInfo boundParams,
 	return plan;
 }
 
+/*
+ * Check the validity of, and replan, only the query at the given 0-based index
+ * in the provided CachedPlanSource.
+ *
+ * Returns a CachedPlan for that specific query. The CachedPlan is not saved in
+ * the CachedPlanSource, so it is the caller's responsibility to free it by
+ * eventually calling ReleaseCachedPlan() on it.
+ */
+CachedPlan *
+GetSingleCachedPlan(CachedPlanSource *plansource, int query_index,
+					ParamListInfo boundParams, QueryEnvironment *queryEnv)
+{
+	List *query_list = plansource->query_list;
+	List *query_list_new;
+	CachedPlan *plan = plansource->gplan,
+			   *newplan;
+	double generic_cost = plansource->generic_cost;
+	double total_custom_cost = plansource->total_custom_cost;
+
+	if (plan == NULL || plan->is_valid)
+		elog(ERROR, "GetSingleCachedPlan() called in the wrong context");
+
+	/*
+	 * Create a new plan for the nth query after revalidating it.
+	 *
+	 * Temporarily reset gplan to ensure that the CachedPlan that it's pointing
+	 * to is not released, because the caller might still need it.
+	 */
+	query_list_new = list_make1(list_nth(plansource->query_list, query_index));
+	plansource->query_list = query_list_new;
+	plansource->gplan = NULL;
+	newplan = GetCachedPlan(plansource, boundParams, NULL, queryEnv);
+	plansource->gplan = plan;
+
+	/* Restore original query_list. */
+	plansource->query_list = query_list;
+	list_free(query_list_new);
+
+	/*
+	 * Restore the original plan costs. The values after the GetCachedPlan()
+	 * call represent the cost of only the nth query, whereas the original
+	 * values represent the cumulative costs for all queries in
+	 * plansource->query_list.
+	 */
+	plansource->generic_cost = generic_cost;
+	plansource->total_custom_cost = total_custom_cost;
+
+	return newplan;
+}
+
 /*
  * ReleaseCachedPlan: release active use of a cached plan.
  *
diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c
index 4a24613537..bf70fd4ce7 100644
--- a/src/backend/utils/mmgr/portalmem.c
+++ b/src/backend/utils/mmgr/portalmem.c
@@ -284,7 +284,8 @@ PortalDefineQuery(Portal portal,
 				  const char *sourceText,
 				  CommandTag commandTag,
 				  List *stmts,
-				  CachedPlan *cplan)
+				  CachedPlan *cplan,
+				  CachedPlanSource *plansource)
 {
 	Assert(PortalIsValid(portal));
 	Assert(portal->status == PORTAL_NEW);
@@ -299,6 +300,7 @@ PortalDefineQuery(Portal portal,
 	portal->commandTag = commandTag;
 	portal->stmts = stmts;
 	portal->cplan = cplan;
+	portal->plansource = plansource;
 	portal->status = PORTAL_DEFINED;
 }
 
diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index bf326eeb70..652e1afbf7 100644
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -102,6 +102,7 @@ extern void ExplainOneUtility(Node *utilityStmt, IntoClause *into,
 							  ParamListInfo params, QueryEnvironment *queryEnv);
 
 extern void ExplainOnePlan(PlannedStmt *plannedstmt, CachedPlan *cplan,
+						   CachedPlanSource *plansource, int plan_index,
 						   IntoClause *into, ExplainState *es,
 						   const char *queryString,
 						   ParamListInfo params, QueryEnvironment *queryEnv,
diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h
index 8a5a9fe642..db21561c8c 100644
--- a/src/include/commands/trigger.h
+++ b/src/include/commands/trigger.h
@@ -258,6 +258,7 @@ extern void ExecASTruncateTriggers(EState *estate,
 extern void AfterTriggerBeginXact(void);
 extern void AfterTriggerBeginQuery(void);
 extern void AfterTriggerEndQuery(EState *estate);
+extern void AfterTriggerAbortQuery(void);
 extern void AfterTriggerFireDeferred(void);
 extern void AfterTriggerEndXact(bool isCommit);
 extern void AfterTriggerBeginSubXact(void);
diff --git a/src/include/executor/execdesc.h b/src/include/executor/execdesc.h
index 0e7245435d..c6ad8fece7 100644
--- a/src/include/executor/execdesc.h
+++ b/src/include/executor/execdesc.h
@@ -36,6 +36,7 @@ typedef struct QueryDesc
 	CmdType		operation;		/* CMD_SELECT, CMD_UPDATE, etc. */
 	PlannedStmt *plannedstmt;	/* planner's output (could be utility, too) */
 	CachedPlan *cplan;			/* CachedPlan that supplies the plannedstmt */
+	bool		release_cplan;	/* Should FreeQueryDesc() release cplan? */
 	const char *sourceText;		/* source text of the query */
 	Snapshot	snapshot;		/* snapshot to use for query */
 	Snapshot	crosscheck_snapshot;	/* crosscheck for RI update/delete */
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 69c3ebff00..ce2447a8cf 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -19,6 +19,7 @@
 #include "nodes/lockoptions.h"
 #include "nodes/parsenodes.h"
 #include "utils/memutils.h"
+#include "utils/plancache.h"
 
 
 /*
@@ -198,6 +199,8 @@ ExecGetJunkAttribute(TupleTableSlot *slot, AttrNumber attno, bool *isNull)
  * prototypes from functions in execMain.c
  */
 extern void ExecutorStart(QueryDesc *queryDesc, int eflags);
+extern void ExecutorStartExt(QueryDesc *queryDesc, int eflags,
+							 CachedPlanSource *plansource, int query_index);
 extern void standard_ExecutorStart(QueryDesc *queryDesc, int eflags);
 extern void ExecutorRun(QueryDesc *queryDesc,
 						ScanDirection direction, uint64 count, bool execute_once);
@@ -261,6 +264,20 @@ extern void ExecEndNode(PlanState *node);
 extern void ExecShutdownNode(PlanState *node);
 extern void ExecSetTupleBound(int64 tuples_needed, PlanState *child_node);
 
+/*
+ * Is the CachedPlan in es_cachedplan still valid?
+ *
+ * Called at various points during ExecutorStart() because invalidation
+ * messages that affect the plan might be received after locks have been
+ * taken on runtime-prunable relations. The caller should take appropriate
+ * action if the plan has become invalid.
+ */
+static inline bool
+ExecPlanStillValid(EState *estate)
+{
+	return estate->es_cachedplan == NULL ? true :
+		CachedPlanStillValid(estate->es_cachedplan);
+}
 
 /* ----------------------------------------------------------------
  *		ExecProcNode
@@ -589,6 +606,7 @@ extern void ExecCreateScanSlotFromOuterPlan(EState *estate,
 extern bool ExecRelationIsTargetRelation(EState *estate, Index scanrelid);
 
 extern Relation ExecOpenScanRelation(EState *estate, Index scanrelid, int eflags);
+extern Relation ExecOpenScanIndexRelation(EState *estate, Oid indexid, int lockmode);
 
 extern void ExecInitRangeTable(EState *estate, List *rangeTable, List *permInfos);
 extern void ExecCloseRangeTableRelations(EState *estate);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index ee089505a0..2a8e5bd784 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -680,6 +680,7 @@ typedef struct EState
 	int			es_top_eflags;	/* eflags passed to ExecutorStart */
 	int			es_instrument;	/* OR of InstrumentOption flags */
 	bool		es_finished;	/* true when ExecutorFinish is done */
+	bool		es_aborted;		/* true when execution was aborted */
 
 	List	   *es_exprcontexts;	/* List of ExprContexts within EState */
 
diff --git a/src/include/utils/plancache.h b/src/include/utils/plancache.h
index 0b5ee007ca..f3ecbd279b 100644
--- a/src/include/utils/plancache.h
+++ b/src/include/utils/plancache.h
@@ -224,6 +224,11 @@ extern CachedPlan *GetCachedPlan(CachedPlanSource *plansource,
 								 ParamListInfo boundParams,
 								 ResourceOwner owner,
 								 QueryEnvironment *queryEnv);
+extern CachedPlan *GetSingleCachedPlan(CachedPlanSource *plansource,
+									   int query_index,
+									   ParamListInfo boundParams,
+									   QueryEnvironment *queryEnv);
+
 extern void ReleaseCachedPlan(CachedPlan *plan, ResourceOwner owner);
 
 extern bool CachedPlanAllowsSimpleValidityCheck(CachedPlanSource *plansource,
@@ -245,4 +250,17 @@ CachedPlanRequiresLocking(CachedPlan *cplan)
 	return cplan->is_generic;
 }
 
+/*
+ * CachedPlanStillValid
+ *      Returns whether a cached generic plan is still valid.
+ *
+ * Invoked by the executor to check if the plan has not been invalidated after
+ * taking locks during the initialization of the plan.
+ */
+static inline bool
+CachedPlanStillValid(CachedPlan *cplan)
+{
+	return cplan->is_valid;
+}
+
 #endif							/* PLANCACHE_H */
diff --git a/src/include/utils/portal.h b/src/include/utils/portal.h
index 29f49829f2..58c3828d2c 100644
--- a/src/include/utils/portal.h
+++ b/src/include/utils/portal.h
@@ -138,6 +138,7 @@ typedef struct PortalData
 	QueryCompletion qc;			/* command completion data for executed query */
 	List	   *stmts;			/* list of PlannedStmts */
 	CachedPlan *cplan;			/* CachedPlan, if stmts are from one */
+	CachedPlanSource *plansource;	/* CachedPlanSource, for cplan */
 
 	ParamListInfo portalParams; /* params to pass to query */
 	QueryEnvironment *queryEnv; /* environment for query */
@@ -241,7 +242,8 @@ extern void PortalDefineQuery(Portal portal,
 							  const char *sourceText,
 							  CommandTag commandTag,
 							  List *stmts,
-							  CachedPlan *cplan);
+							  CachedPlan *cplan,
+							  CachedPlanSource *plansource);
 extern PlannedStmt *PortalGetPrimaryStmt(Portal portal);
 extern void PortalCreateHoldStore(Portal portal);
 extern void PortalHashTableDeleteAll(void);
diff --git a/src/test/modules/delay_execution/Makefile b/src/test/modules/delay_execution/Makefile
index 70f24e846d..3eeb097fde 100644
--- a/src/test/modules/delay_execution/Makefile
+++ b/src/test/modules/delay_execution/Makefile
@@ -8,7 +8,8 @@ OBJS = \
 	delay_execution.o
 
 ISOLATION = partition-addition \
-	    partition-removal-1
+	    partition-removal-1 \
+		cached-plan-inval
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config
diff --git a/src/test/modules/delay_execution/delay_execution.c b/src/test/modules/delay_execution/delay_execution.c
index 155c8a8d55..0b5f317cd1 100644
--- a/src/test/modules/delay_execution/delay_execution.c
+++ b/src/test/modules/delay_execution/delay_execution.c
@@ -1,14 +1,18 @@
 /*-------------------------------------------------------------------------
  *
  * delay_execution.c
- *		Test module to allow delay between parsing and execution of a query.
+ *		Test module to introduce delay at various points during execution of a
+ *		query to test that execution proceeds safely in light of concurrent
+ *		changes.
  *
  * The delay is implemented by taking and immediately releasing a specified
  * advisory lock.  If another process has previously taken that lock, the
  * current process will be blocked until the lock is released; otherwise,
  * there's no effect.  This allows an isolationtester script to reliably
- * test behaviors where some specified action happens in another backend
- * between parsing and execution of any desired query.
+ * test behaviors where some specified action happens in another backend in
+ * a couple of cases: 1) between parsing and execution of any desired query
+ * when using the planner_hook, 2) between RevalidateCachedQuery() and
+ * ExecutorStart() when using the ExecutorStart_hook.
  *
  * Copyright (c) 2020-2024, PostgreSQL Global Development Group
  *
@@ -22,6 +26,7 @@
 
 #include <limits.h>
 
+#include "executor/executor.h"
 #include "optimizer/planner.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -32,9 +37,11 @@ PG_MODULE_MAGIC;
 
 /* GUC: advisory lock ID to use.  Zero disables the feature. */
 static int	post_planning_lock_id = 0;
+static int	executor_start_lock_id = 0;
 
-/* Save previous planner hook user to be a good citizen */
+/* Save previous hook users to be a good citizen */
 static planner_hook_type prev_planner_hook = NULL;
+static ExecutorStart_hook_type prev_ExecutorStart_hook = NULL;
 
 
 /* planner_hook function to provide the desired delay */
@@ -70,11 +77,41 @@ delay_execution_planner(Query *parse, const char *query_string,
 	return result;
 }
 
+/* ExecutorStart_hook function to provide the desired delay */
+static void
+delay_execution_ExecutorStart(QueryDesc *queryDesc, int eflags)
+{
+	/* If enabled, delay by taking and releasing the specified lock */
+	if (executor_start_lock_id != 0)
+	{
+		DirectFunctionCall1(pg_advisory_lock_int8,
+							Int64GetDatum((int64) executor_start_lock_id));
+		DirectFunctionCall1(pg_advisory_unlock_int8,
+							Int64GetDatum((int64) executor_start_lock_id));
+
+		/*
+		 * Ensure that we notice any pending invalidations, since the advisory
+		 * lock functions don't do this.
+		 */
+		AcceptInvalidationMessages();
+	}
+
+	/* Now start the executor, possibly via a previous hook user */
+	if (prev_ExecutorStart_hook)
+		prev_ExecutorStart_hook(queryDesc, eflags);
+	else
+		standard_ExecutorStart(queryDesc, eflags);
+
+	if (executor_start_lock_id != 0)
+		elog(NOTICE, "Finished ExecutorStart(): CachedPlan is %s",
+			 CachedPlanStillValid(queryDesc->cplan) ? "valid" : "not valid");
+}
+
 /* Module load function */
 void
 _PG_init(void)
 {
-	/* Set up the GUC to control which lock is used */
+	/* Set up GUCs to control which lock is used */
 	DefineCustomIntVariable("delay_execution.post_planning_lock_id",
 							"Sets the advisory lock ID to be locked/unlocked after planning.",
 							"Zero disables the delay.",
@@ -86,10 +123,22 @@ _PG_init(void)
 							NULL,
 							NULL,
 							NULL);
-
+	DefineCustomIntVariable("delay_execution.executor_start_lock_id",
+							"Sets the advisory lock ID to be locked/unlocked before starting execution.",
+							"Zero disables the delay.",
+							&executor_start_lock_id,
+							0,
+							0, INT_MAX,
+							PGC_USERSET,
+							0,
+							NULL,
+							NULL,
+							NULL);
 	MarkGUCPrefixReserved("delay_execution");
 
-	/* Install our hook */
+	/* Install our hooks. */
 	prev_planner_hook = planner_hook;
 	planner_hook = delay_execution_planner;
+	prev_ExecutorStart_hook = ExecutorStart_hook;
+	ExecutorStart_hook = delay_execution_ExecutorStart;
 }
diff --git a/src/test/modules/delay_execution/expected/cached-plan-inval.out b/src/test/modules/delay_execution/expected/cached-plan-inval.out
new file mode 100644
index 0000000000..e8efb6d9d9
--- /dev/null
+++ b/src/test/modules/delay_execution/expected/cached-plan-inval.out
@@ -0,0 +1,175 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1prep s2lock s1exec s2dropi s2unlock
+step s1prep: SET plan_cache_mode = force_generic_plan;
+		  PREPARE q AS SELECT * FROM foov WHERE a = $1 FOR UPDATE;
+		  EXPLAIN (COSTS OFF) EXECUTE q (1);
+QUERY PLAN                                      
+------------------------------------------------
+LockRows                                        
+  ->  Append                                    
+        Subplans Removed: 2                     
+        ->  Bitmap Heap Scan on foo12_1 foo_1   
+              Recheck Cond: (a = $1)            
+              ->  Bitmap Index Scan on foo12_1_a
+                    Index Cond: (a = $1)        
+(7 rows)
+
+step s2lock: SELECT pg_advisory_lock(12345);
+pg_advisory_lock
+----------------
+                
+(1 row)
+
+step s1exec: LOAD 'delay_execution';
+		  SET delay_execution.executor_start_lock_id = 12345;
+		  EXPLAIN (COSTS OFF) EXECUTE q (1); <waiting ...>
+step s2dropi: DROP INDEX foo12_1_a;
+step s2unlock: SELECT pg_advisory_unlock(12345);
+pg_advisory_unlock
+------------------
+t                 
+(1 row)
+
+step s1exec: <... completed>
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is not valid
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is valid
+QUERY PLAN                           
+-------------------------------------
+LockRows                             
+  ->  Append                         
+        Subplans Removed: 2          
+        ->  Seq Scan on foo12_1 foo_1
+              Filter: (a = $1)       
+(5 rows)
+
+
+starting permutation: s1prep2 s2lock s1exec2 s2dropi s2unlock
+step s1prep2: SET plan_cache_mode = force_generic_plan;
+		  PREPARE q2 AS SELECT * FROM foov WHERE a = one() or a = two();
+		  EXPLAIN (COSTS OFF) EXECUTE q2;
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is valid
+QUERY PLAN                                        
+--------------------------------------------------
+Append                                            
+  Subplans Removed: 1                             
+  ->  Bitmap Heap Scan on foo12_1 foo_1           
+        Recheck Cond: ((a = one()) OR (a = two()))
+        ->  BitmapOr                              
+              ->  Bitmap Index Scan on foo12_1_a  
+                    Index Cond: (a = one())       
+              ->  Bitmap Index Scan on foo12_1_a  
+                    Index Cond: (a = two())       
+  ->  Seq Scan on foo12_2 foo_2                   
+        Filter: ((a = one()) OR (a = two()))      
+(11 rows)
+
+step s2lock: SELECT pg_advisory_lock(12345);
+pg_advisory_lock
+----------------
+                
+(1 row)
+
+step s1exec2: LOAD 'delay_execution';
+		  SET delay_execution.executor_start_lock_id = 12345;
+		  EXPLAIN (COSTS OFF) EXECUTE q2; <waiting ...>
+step s2dropi: DROP INDEX foo12_1_a;
+step s2unlock: SELECT pg_advisory_unlock(12345);
+pg_advisory_unlock
+------------------
+t                 
+(1 row)
+
+step s1exec2: <... completed>
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is not valid
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is valid
+QUERY PLAN                                  
+--------------------------------------------
+Append                                      
+  Subplans Removed: 1                       
+  ->  Seq Scan on foo12_1 foo_1             
+        Filter: ((a = one()) OR (a = two()))
+  ->  Seq Scan on foo12_2 foo_2             
+        Filter: ((a = one()) OR (a = two()))
+(6 rows)
+
+
+starting permutation: s1prep3 s2lock s1exec3 s2dropi s2unlock
+step s1prep3: SET plan_cache_mode = force_generic_plan;
+		  PREPARE q3 AS UPDATE foov SET a = a WHERE a = one() or a = two();
+		  EXPLAIN (COSTS OFF) EXECUTE q3;
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is valid
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is valid
+QUERY PLAN                                              
+--------------------------------------------------------
+Append                                                  
+  Subplans Removed: 1                                   
+  ->  Bitmap Heap Scan on foo12_1 foo_1                 
+        Recheck Cond: ((a = one()) OR (a = two()))      
+        ->  BitmapOr                                    
+              ->  Bitmap Index Scan on foo12_1_a        
+                    Index Cond: (a = one())             
+              ->  Bitmap Index Scan on foo12_1_a        
+                    Index Cond: (a = two())             
+  ->  Seq Scan on foo12_2 foo_2                         
+        Filter: ((a = one()) OR (a = two()))            
+                                                        
+Update on foo                                           
+  Update on foo12_1 foo_1                               
+  Update on foo12_2 foo_2                               
+  Update on foo3 foo                                    
+  ->  Append                                            
+        Subplans Removed: 1                             
+        ->  Bitmap Heap Scan on foo12_1 foo_1           
+              Recheck Cond: ((a = one()) OR (a = two()))
+              ->  BitmapOr                              
+                    ->  Bitmap Index Scan on foo12_1_a  
+                          Index Cond: (a = one())       
+                    ->  Bitmap Index Scan on foo12_1_a  
+                          Index Cond: (a = two())       
+        ->  Seq Scan on foo12_2 foo_2                   
+              Filter: ((a = one()) OR (a = two()))      
+(27 rows)
+
+step s2lock: SELECT pg_advisory_lock(12345);
+pg_advisory_lock
+----------------
+                
+(1 row)
+
+step s1exec3: LOAD 'delay_execution';
+		  SET delay_execution.executor_start_lock_id = 12345;
+		  EXPLAIN (COSTS OFF) EXECUTE q3; <waiting ...>
+step s2dropi: DROP INDEX foo12_1_a;
+step s2unlock: SELECT pg_advisory_unlock(12345);
+pg_advisory_unlock
+------------------
+t                 
+(1 row)
+
+step s1exec3: <... completed>
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is not valid
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is valid
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is not valid
+s1: NOTICE:  Finished ExecutorStart(): CachedPlan is valid
+QUERY PLAN                                        
+--------------------------------------------------
+Append                                            
+  Subplans Removed: 1                             
+  ->  Seq Scan on foo12_1 foo_1                   
+        Filter: ((a = one()) OR (a = two()))      
+  ->  Seq Scan on foo12_2 foo_2                   
+        Filter: ((a = one()) OR (a = two()))      
+                                                  
+Update on foo                                     
+  Update on foo12_1 foo_1                         
+  Update on foo12_2 foo_2                         
+  Update on foo3 foo                              
+  ->  Append                                      
+        Subplans Removed: 1                       
+        ->  Seq Scan on foo12_1 foo_1             
+              Filter: ((a = one()) OR (a = two()))
+        ->  Seq Scan on foo12_2 foo_2             
+              Filter: ((a = one()) OR (a = two()))
+(17 rows)
+
diff --git a/src/test/modules/delay_execution/meson.build b/src/test/modules/delay_execution/meson.build
index 41f3ac0b89..5a70b183d0 100644
--- a/src/test/modules/delay_execution/meson.build
+++ b/src/test/modules/delay_execution/meson.build
@@ -24,6 +24,7 @@ tests += {
     'specs': [
       'partition-addition',
       'partition-removal-1',
+      'cached-plan-inval',
     ],
   },
 }
diff --git a/src/test/modules/delay_execution/specs/cached-plan-inval.spec b/src/test/modules/delay_execution/specs/cached-plan-inval.spec
new file mode 100644
index 0000000000..5b1f72b4a8
--- /dev/null
+++ b/src/test/modules/delay_execution/specs/cached-plan-inval.spec
@@ -0,0 +1,65 @@
+# Test to check that invalidation of cached generic plans during ExecutorStart
+# correctly triggers replanning and re-execution.
+
+setup
+{
+  CREATE TABLE foo (a int, b text) PARTITION BY LIST(a);
+  CREATE TABLE foo12 PARTITION OF foo FOR VALUES IN (1, 2) PARTITION BY LIST (a);
+  CREATE TABLE foo12_1 PARTITION OF foo12 FOR VALUES IN (1);
+  CREATE TABLE foo12_2 PARTITION OF foo12 FOR VALUES IN (2);
+  CREATE INDEX foo12_1_a ON foo12_1 (a);
+  CREATE TABLE foo3 PARTITION OF foo FOR VALUES IN (3);
+  CREATE VIEW foov AS SELECT * FROM foo;
+  CREATE FUNCTION one () RETURNS int AS $$ BEGIN RETURN 1; END; $$ LANGUAGE PLPGSQL STABLE;
+  CREATE FUNCTION two () RETURNS int AS $$ BEGIN RETURN 2; END; $$ LANGUAGE PLPGSQL STABLE;
+  CREATE RULE update_foo AS ON UPDATE TO foo DO ALSO SELECT 1;
+}
+
+teardown
+{
+  DROP VIEW foov;
+  DROP RULE update_foo ON foo;
+  DROP TABLE foo;
+  DROP FUNCTION one(), two();
+}
+
+session "s1"
+# Append with run-time pruning
+step "s1prep"   { SET plan_cache_mode = force_generic_plan;
+		  PREPARE q AS SELECT * FROM foov WHERE a = $1 FOR UPDATE;
+		  EXPLAIN (COSTS OFF) EXECUTE q (1); }
+
+# Another case with Append with run-time pruning
+step "s1prep2"   { SET plan_cache_mode = force_generic_plan;
+		  PREPARE q2 AS SELECT * FROM foov WHERE a = one() or a = two();
+		  EXPLAIN (COSTS OFF) EXECUTE q2; }
+
+# Case with a rule adding another query
+step "s1prep3"   { SET plan_cache_mode = force_generic_plan;
+		  PREPARE q3 AS UPDATE foov SET a = a WHERE a = one() or a = two();
+		  EXPLAIN (COSTS OFF) EXECUTE q3; }
+
+# Executes a generic plan
+step "s1exec"	{ LOAD 'delay_execution';
+		  SET delay_execution.executor_start_lock_id = 12345;
+		  EXPLAIN (COSTS OFF) EXECUTE q (1); }
+step "s1exec2"	{ LOAD 'delay_execution';
+		  SET delay_execution.executor_start_lock_id = 12345;
+		  EXPLAIN (COSTS OFF) EXECUTE q2; }
+step "s1exec3"	{ LOAD 'delay_execution';
+		  SET delay_execution.executor_start_lock_id = 12345;
+		  EXPLAIN (COSTS OFF) EXECUTE q3; }
+
+session "s2"
+step "s2lock"	{ SELECT pg_advisory_lock(12345); }
+step "s2unlock"	{ SELECT pg_advisory_unlock(12345); }
+step "s2dropi"	{ DROP INDEX foo12_1_a; }
+
+# While "s1exec", etc. wait to acquire the advisory lock, "s2drop" is able to
+# drop the index being used in the cached plan.  When "s1exec" is then
+# unblocked and initializes the cached plan for execution, it detects the
+# concurrent index drop and causes the cached plan to be discarded and
+# recreated without the index.
+permutation "s1prep" "s2lock" "s1exec" "s2dropi" "s2unlock"
+permutation "s1prep2" "s2lock" "s1exec2" "s2dropi" "s2unlock"
+permutation "s1prep3" "s2lock" "s1exec3" "s2dropi" "s2unlock"
-- 
2.43.0