v26-0001-This-is-https-commitfest.postgresql.org-50-5160-.patch

From b5197137540c7301bfe11e61cc02cb6e17d84b8a Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Tue, 31 Dec 2024 14:09:52 +0100
Subject: [PATCH v26 1/8] This is https://commitfest.postgresql.org/50/5160/
 and https://commitfest.postgresql.org/patch/5438/ merged in single commit. it
 is required for stability of stress tests.

---
 contrib/amcheck/verify_nbtree.c        |  68 ++++++-------
 src/backend/commands/indexcmds.c       |   4 +-
 src/backend/executor/execIndexing.c    |   3 +
 src/backend/executor/execPartition.c   | 119 +++++++++++++++++++---
 src/backend/executor/nodeModifyTable.c |   2 +
 src/backend/optimizer/util/plancat.c   | 135 ++++++++++++++++++-------
 src/backend/utils/time/snapmgr.c       |   2 +
 7 files changed, 245 insertions(+), 88 deletions(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 0949c88983a..2445f001700 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -382,7 +382,6 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 	BTMetaPageData *metad;
 	uint32		previouslevel;
 	BtreeLevel	current;
-	Snapshot	snapshot = SnapshotAny;
 
 	if (!readonly)
 		elog(DEBUG1, "verifying consistency of tree structure for index \"%s\"",
@@ -433,38 +432,35 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 		state->heaptuplespresent = 0;
 
 		/*
-		 * Register our own snapshot in !readonly case, rather than asking
+		 * Register our own snapshot for heapallindexed, rather than asking
 		 * table_index_build_scan() to do this for us later.  This needs to
 		 * happen before index fingerprinting begins, so we can later be
 		 * certain that index fingerprinting should have reached all tuples
 		 * returned by table_index_build_scan().
 		 */
-		if (!state->readonly)
-		{
-			snapshot = RegisterSnapshot(GetTransactionSnapshot());
+		state->snapshot = RegisterSnapshot(GetTransactionSnapshot());
 
-			/*
-			 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
-			 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
-			 * the entries it requires in the index.
-			 *
-			 * We must defend against the possibility that an old xact
-			 * snapshot was returned at higher isolation levels when that
-			 * snapshot is not safe for index scans of the target index.  This
-			 * is possible when the snapshot sees tuples that are before the
-			 * index's indcheckxmin horizon.  Throwing an error here should be
-			 * very rare.  It doesn't seem worth using a secondary snapshot to
-			 * avoid this.
-			 */
-			if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
-				!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
-									   snapshot->xmin))
-				ereport(ERROR,
-						(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
-						 errmsg("index \"%s\" cannot be verified using transaction snapshot",
-								RelationGetRelationName(rel))));
-		}
-	}
+		/*
+		 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+		 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+		 * the entries it requires in the index.
+		 *
+		 * We must defend against the possibility that an old xact
+		 * snapshot was returned at higher isolation levels when that
+		 * snapshot is not safe for index scans of the target index.  This
+		 * is possible when the snapshot sees tuples that are before the
+		 * index's indcheckxmin horizon.  Throwing an error here should be
+		 * very rare.  It doesn't seem worth using a secondary snapshot to
+		 * avoid this.
+		 */
+		if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+			!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								   state->snapshot->xmin))
+			ereport(ERROR,
+					(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+							RelationGetRelationName(rel))));
+}
 
 	/*
 	 * We need a snapshot to check the uniqueness of the index. For better
@@ -476,9 +472,7 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 		state->indexinfo = BuildIndexInfo(state->rel);
 		if (state->indexinfo->ii_Unique)
 		{
-			if (snapshot != SnapshotAny)
-				state->snapshot = snapshot;
-			else
+			if (state->snapshot == InvalidSnapshot)
 				state->snapshot = RegisterSnapshot(GetTransactionSnapshot());
 		}
 	}
@@ -555,13 +549,12 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 		/*
 		 * Create our own scan for table_index_build_scan(), rather than
 		 * getting it to do so for us.  This is required so that we can
-		 * actually use the MVCC snapshot registered earlier in !readonly
-		 * case.
+		 * actually use the MVCC snapshot registered earlier.
 		 *
 		 * Note that table_index_build_scan() calls heap_endscan() for us.
 		 */
 		scan = table_beginscan_strat(state->heaprel,	/* relation */
-									 snapshot,	/* snapshot */
+									 state->snapshot,	/* snapshot */
 									 0, /* number of keys */
 									 NULL,	/* scan key */
 									 true,	/* buffer access strategy OK */
@@ -569,7 +562,7 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 
 		/*
 		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY
-		 * behaves in !readonly case.
+		 * behaves.
 		 *
 		 * It's okay that we don't actually use the same lock strength for the
 		 * heap relation as any other ii_Concurrent caller would in !readonly
@@ -578,7 +571,7 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 		 * that needs to be sure that there was no concurrent recycling of
 		 * TIDs.
 		 */
-		indexinfo->ii_Concurrent = !state->readonly;
+		indexinfo->ii_Concurrent = true;
 
 		/*
 		 * Don't wait for uncommitted tuple xact commit/abort when index is a
@@ -602,14 +595,11 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 								 state->heaptuplespresent, RelationGetRelationName(heaprel),
 								 100.0 * bloom_prop_bits_set(state->filter))));
 
-		if (snapshot != SnapshotAny)
-			UnregisterSnapshot(snapshot);
-
 		bloom_free(state->filter);
 	}
 
 	/* Be tidy: */
-	if (snapshot == SnapshotAny && state->snapshot != InvalidSnapshot)
+	if (state->snapshot != InvalidSnapshot)
 		UnregisterSnapshot(state->snapshot);
 	MemoryContextDelete(state->targetcontext);
 }
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 5712fac3697..974243c5c60 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1789,6 +1789,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4228,7 +4229,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap", NULL);
 	StartTransactionCommand();
 
 	/*
@@ -4307,6 +4308,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 401606f840a..df7e7bce86d 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -942,6 +943,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict", NULL);
 
 	return !conflict;
 }
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index aa12e9ad2ea..066686483f0 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -490,6 +490,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -701,6 +743,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -711,23 +755,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 4c5647ac38a..f6d2a6ede93 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -70,6 +70,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1179,6 +1180,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative", NULL);
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d950bd93002..ff416f0522c 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -808,12 +808,14 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -848,8 +850,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -861,30 +863,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -907,7 +955,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -927,27 +981,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
-			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -967,7 +1017,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -975,6 +1025,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -1012,27 +1066,35 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -1040,7 +1102,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 65561cc6bc3..8e1a918f130 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -123,6 +123,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -458,6 +459,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end", NULL);
 	}
 }
 
-- 
2.43.0