Check for hasPseudoconstantQuals differently

src/backend/distributed/planner/distributed_planner.c

@@ -2002,8 +2002,6 @@ multi_relation_restriction_hook(PlannerInfo *root, RelOptInfo *relOptInfo,
 	relationRestriction->outerPlanParamsList = OuterPlanParamsList(root);
 	relationRestriction->translatedVars = TranslatedVars(root,
 														 relationRestriction->index);
-	plannerRestrictionContext->relationRestrictionContext->hasPseudoConstantQuals =
-		root->hasPseudoConstantQuals;
 
 	RelationRestrictionContext *relationRestrictionContext =
 		plannerRestrictionContext->relationRestrictionContext;

src/backend/distributed/planner/recursive_planning.c

@@ -193,6 +193,10 @@ static Query * CreateOuterSubquery(RangeTblEntry *rangeTableEntry,
 								   List *outerSubqueryTargetList);
 static List * GenerateRequiredColNamesFromTargetList(List *targetList);
 static char * GetRelationNameAndAliasName(RangeTblEntry *rangeTablentry);
+#if PG_VERSION_NUM < PG_VERSION_17
+static bool hasPseudoconstantQuals(
+	RelationRestrictionContext *relationRestrictionContext);
+#endif
 
 /*
  * GenerateSubplansForSubqueriesAndCTEs is a wrapper around RecursivelyPlanSubqueriesAndCTEs.
@@ -481,25 +485,23 @@ ShouldRecursivelyPlanOuterJoins(Query *query, RecursivePlanningContext *context)
 	bool hasOuterJoin =
 		context->plannerRestrictionContext->joinRestrictionContext->hasOuterJoin;
 #if PG_VERSION_NUM < PG_VERSION_17
-	bool hasPseudoConstantQuals =
+	if (!hasOuterJoin)
-		context->plannerRestrictionContext->relationRestrictionContext->
-		hasPseudoConstantQuals;
-
-	/*
-	 * PG15 commit d1ef5631e620f9a5b6480a32bb70124c857af4f1
-	 * PG16 commit 695f5deb7902865901eb2d50a70523af655c3a00
-	 * disallows replacing joins with scans in queries with pseudoconstant quals.
-	 * This commit prevents the set_join_pathlist_hook from being called
-	 * if any of the join restrictions is a pseudo-constant.
-	 * So in these cases, citus has no info on the join, never sees that the query
-	 * has an outer join, and ends up producing an incorrect plan.
-	 * PG17 fixes this by commit 9e9931d2bf40e2fea447d779c2e133c2c1256ef3
-	 * Therefore, we take this extra measure here for PG versions less than 17.
-	 */
-	if (hasPseudoConstantQuals && !hasOuterJoin)
 	{
-		if (FindNodeMatchingCheckFunction((Node *) query->jointree,
+		/*
-										  IsOuterJoinExpr))
+		 * PG15 commit d1ef5631e620f9a5b6480a32bb70124c857af4f1
+		 * PG16 commit 695f5deb7902865901eb2d50a70523af655c3a00
+		 * disallows replacing joins with scans in queries with pseudoconstant quals.
+		 * This commit prevents the set_join_pathlist_hook from being called
+		 * if any of the join restrictions is a pseudo-constant.
+		 * So in these cases, citus has no info on the join, never sees that the query
+		 * has an outer join, and ends up producing an incorrect plan.
+		 * PG17 fixes this by commit 9e9931d2bf40e2fea447d779c2e133c2c1256ef3
+		 * Therefore, we take this extra measure here for PG versions less than 17.
+		 * hasOuterJoin can never be true when set_join_pathlist_hook is absent.
+		 */
+		if (hasPseudoconstantQuals(
+				context->plannerRestrictionContext->relationRestrictionContext) &&
+			FindNodeMatchingCheckFunction((Node *) query->jointree, IsOuterJoinExpr))
 		{
 			ereport(ERROR, (errmsg("Distributed queries with outer joins and "
 								   "pseudoconstant quals are not supported in PG15 and PG16."),
@@ -2142,7 +2144,6 @@ TransformFunctionRTE(RangeTblEntry *rangeTblEntry)
 			subquery->targetList = lappend(subquery->targetList, targetEntry);
 		}
 	}
-
 	/*
 	 * If tupleDesc is NULL we have 2 different cases:
 	 *
@@ -2192,7 +2193,6 @@ TransformFunctionRTE(RangeTblEntry *rangeTblEntry)
 				columnType = list_nth_oid(rangeTblFunction->funccoltypes,
 										  targetColumnIndex);
 			}
-
 			/* use the types in the function definition otherwise */
 			else
 			{
@@ -2616,3 +2616,29 @@ GeneratingSubplans(void)
 {
 	return recursivePlanningDepth > 0;
 }
+
+
+#if PG_VERSION_NUM < PG_VERSION_17
+
+/*
+ * hasPseudoconstantQuals returns true if any of the planner infos in the
+ * relation restriction list of the input relation restriction context
+ * has a pseudoconstant qual
+ */
+static bool
+hasPseudoconstantQuals(RelationRestrictionContext *relationRestrictionContext)
+{
+	ListCell *objectCell = NULL;
+	foreach(objectCell, relationRestrictionContext->relationRestrictionList)
+	{
+		if (((RelationRestriction *) lfirst(
+				 objectCell))->plannerInfo->hasPseudoConstantQuals)
+		{
+			return true;
+		}
+	}
+	return false;
+}
+
+
+#endif

src/include/distributed/distributed_planner.h

@@ -36,7 +36,6 @@ extern int PlannerLevel;
 typedef struct RelationRestrictionContext
 {
 	bool allReferenceTables;
-	bool hasPseudoConstantQuals;
 	List *relationRestrictionList;
 } RelationRestrictionContext;