Fix compiler errors

src/backend/distributed/planner/merge_planner.c

@@ -157,6 +157,32 @@ CreateMergePlan(uint64 planId, Query *originalQuery, Query *query,
 }
 
 
+/*
+ * GetMergeJoinConditionList returns all the Join conditions from the ON clause
+ */
+List *
+GetMergeJoinConditionList(Query *mergeQuery)
+{
+#if PG_VERSION_NUM >= PG_VERSION_17
+	List *mergeJoinConditionList = NIL;
+	if (IsA(mergeQuery->mergeJoinCondition, List))
+	{
+		mergeJoinConditionList = (List *) mergeQuery->mergeJoinCondition;
+	}
+	else
+	{
+		Node *joinClause =
+			eval_const_expressions(NULL, mergeQuery->mergeJoinCondition);
+		joinClause = (Node *) canonicalize_qual((Expr *) joinClause, false);
+		mergeJoinConditionList = make_ands_implicit((Expr *) joinClause);
+	}
+#else
+	List *mergeJoinConditionList = WhereClauseList(mergeQuery->jointree);
+#endif
+	return mergeJoinConditionList;
+}
+
+
 #if PG_VERSION_NUM >= PG_VERSION_15
 
 /*
@@ -563,7 +589,6 @@ MergeQualAndTargetListFunctionsSupported(Oid resultRelationId, Query *query,
 										 List *targetList, CmdType commandType)
 {
 	uint32 targetRangeTableIndex = query->resultRelation;
-	FromExpr *joinTree = query->jointree;
 	Var *distributionColumn = NULL;
 	if (IsCitusTable(resultRelationId) && HasDistributionKey(resultRelationId))
 	{
@@ -601,7 +626,8 @@ MergeQualAndTargetListFunctionsSupported(Oid resultRelationId, Query *query,
 		}
 
 		if (targetEntryDistributionColumn &&
-			TargetEntryChangesValue(targetEntry, distributionColumn, joinTree))
+			TargetEntryChangesValue(targetEntry, distributionColumn, (Node *) query,
+									CMD_MERGE))
 		{
 			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
 								 "updating the distribution column is not "
@@ -723,8 +749,13 @@ ErrorIfRepartitionMergeNotSupported(Oid targetRelationId, Query *mergeQuery,
 	/*
 	 * Sub-queries and CTEs are not allowed in actions and ON clause
 	 */
-	if (FindNodeMatchingCheckFunction((Node *) mergeQuery->mergeJoinCondition,
+#if PG_VERSION_NUM >= PG_VERSION_17
-									  IsNodeSubquery))
+	Node *joinCondition = (Node *) mergeQuery->mergeJoinCondition;
+#else
+	Node *joinCondition = (Node *) mergeQuery->jointree->quals;
+#endif
+
+	if (FindNodeMatchingCheckFunction(joinCondition, IsNodeSubquery))
 	{
 		ereport(ERROR,
 				(errmsg("Sub-queries and CTEs are not allowed in ON clause for MERGE "
@@ -1224,11 +1255,17 @@ ErrorIfMergeQueryQualAndTargetListNotSupported(Oid targetRelationId, Query *orig
 							   "supported in MERGE sql with distributed tables")));
 	}
 
+#if PG_VERSION_NUM >= PG_VERSION_17
+	Node *joinCondition = (Node *) originalQuery->mergeJoinCondition;
+#else
+	Node *joinCondition = (Node *) originalQuery->jointree->quals;
+#endif
+
 	DeferredErrorMessage *deferredError =
 		MergeQualAndTargetListFunctionsSupported(
 			targetRelationId,
 			originalQuery,
-			originalQuery->mergeJoinCondition,
+			joinCondition,
 			originalQuery->targetList,
 			originalQuery->commandType);
 
@@ -1304,20 +1341,7 @@ static int
 SourceResultPartitionColumnIndex(Query *mergeQuery, List *sourceTargetList,
 								 CitusTableCacheEntry *targetRelation)
 {
-	/* Get all the Join conditions from the ON clause */
+	List *mergeJoinConditionList = GetMergeJoinConditionList(mergeQuery);
-	List *mergeJoinConditionList = NIL;
-	if (IsA(mergeQuery->mergeJoinCondition, List))
-	{
-		mergeJoinConditionList = (List *) mergeQuery->mergeJoinCondition;
-	}
-	else
-	{
-		Node *joinClause =
-			eval_const_expressions(NULL, mergeQuery->mergeJoinCondition);
-		joinClause = (Node *) canonicalize_qual((Expr *) joinClause, false);
-		mergeJoinConditionList = make_ands_implicit((Expr *) joinClause);
-	}
-
 	Var *targetColumn = targetRelation->partitionColumn;
 	Var *sourceRepartitionVar = NULL;
 	bool foundTypeMismatch = false;

src/backend/distributed/planner/multi_router_planner.c

@@ -597,9 +597,9 @@ TargetlistAndFunctionsSupported(Oid resultRelationId, FromExpr *joinTree, Node *
 								 NULL, NULL);
 		}
 
-		if (commandType == CMD_UPDATE && targetEntryPartitionColumn &&
+		if (targetEntryPartitionColumn &&
 			TargetEntryChangesValue(targetEntry, partitionColumn,
-									joinTree))
+									(Node *) joinTree, commandType))
 		{
 			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
 								 "modifying the partition value of rows is not "
@@ -1611,8 +1611,15 @@ MasterIrreducibleExpressionFunctionChecker(Oid func_id, void *context)
  * tree, or the target entry sets a different column.
  */
 bool
-TargetEntryChangesValue(TargetEntry *targetEntry, Var *column, FromExpr *joinTree)
+TargetEntryChangesValue(TargetEntry *targetEntry, Var *column, Node *node, CmdType
+						commandType)
 {
+	if (commandType != CMD_UPDATE && commandType != CMD_MERGE)
+	{
+		/* no-op */
+		return false;
+	}
+
 	bool isColumnValueChanged = true;
 	Expr *setExpr = targetEntry->expr;
 
@@ -1628,7 +1635,6 @@ TargetEntryChangesValue(TargetEntry *targetEntry, Var *column, FromExpr *joinTre
 	else if (IsA(setExpr, Const))
 	{
 		Const *newValue = (Const *) setExpr;
-		List *restrictClauseList = WhereClauseList(joinTree);
 		OpExpr *equalityExpr = MakeOpExpression(column, BTEqualStrategyNumber);
 		Node *rightOp = get_rightop((Expr *) equalityExpr);
 
@@ -1640,6 +1646,16 @@ TargetEntryChangesValue(TargetEntry *targetEntry, Var *column, FromExpr *joinTre
 		rightConst->constisnull = newValue->constisnull;
 		rightConst->constbyval = newValue->constbyval;
 
+		List *restrictClauseList = NIL;
+		if (commandType == CMD_UPDATE)
+		{
+			restrictClauseList = WhereClauseList((FromExpr *) node);
+		}
+		else
+		{
+			restrictClauseList = GetMergeJoinConditionList((Query *) node);
+		}
+
 		bool predicateIsImplied = predicate_implied_by(list_make1(equalityExpr),
 													   restrictClauseList, false);
 		if (predicateIsImplied)

src/include/distributed/merge_planner.h

@@ -32,6 +32,7 @@ extern void NonPushableMergeCommandExplainScan(CustomScanState *node, List *ance
 											   struct ExplainState *es);
 extern Var * FetchAndValidateInsertVarIfExists(Oid targetRelationId, Query *query);
 extern RangeTblEntry * ExtractMergeSourceRangeTableEntry(Query *query, bool joinSourceOk);
+extern List * GetMergeJoinConditionList(Query *mergeQuery);
 
 
 #endif /* MERGE_PLANNER_H */

src/include/distributed/multi_router_planner.h

@@ -111,7 +111,7 @@ extern DeferredErrorMessage * TargetlistAndFunctionsSupported(Oid resultRelation
 															  List *returningList);
 extern bool NodeIsFieldStore(Node *node);
 extern bool TargetEntryChangesValue(TargetEntry *targetEntry, Var *column,
-									FromExpr *joinTree);
+									Node *node, CmdType commandType);
 extern bool MasterIrreducibleExpression(Node *expression, bool *varArgument,
 										bool *badCoalesce);
 extern bool HasDangerousJoinUsing(List *rtableList, Node *jtnode);

src/test/regress/expected/merge_unsupported_0.out

@@ -0,0 +1,6 @@
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 15 AS server_version_ge_15
+\gset
+\if :server_version_ge_15
+\else
+\q