diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 5d18206b91b..ad07baa60c9 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -53,7 +53,7 @@ get_relation_info_hook_type get_relation_info_hook = NULL;
 
 
 static void get_relation_foreign_keys(PlannerInfo *root, RelOptInfo *rel,
-						  Relation relation);
+						  Relation relation, bool inhparent);
 static bool infer_collation_opclass_match(InferenceElem *elem, Relation idxRel,
 							  List *idxExprs);
 static int32 get_rel_data_width(Relation rel, int32 *attr_widths);
@@ -408,7 +408,7 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 	}
 
 	/* Collect info about relation's foreign keys, if relevant */
-	get_relation_foreign_keys(root, rel, relation);
+	get_relation_foreign_keys(root, rel, relation, inhparent);
 
 	heap_close(relation, NoLock);
 
@@ -433,7 +433,7 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
  */
 static void
 get_relation_foreign_keys(PlannerInfo *root, RelOptInfo *rel,
-						  Relation relation)
+						  Relation relation, bool inhparent)
 {
 	List	   *rtable = root->parse->rtable;
 	List	   *cachedfkeys;
@@ -448,6 +448,15 @@ get_relation_foreign_keys(PlannerInfo *root, RelOptInfo *rel,
 		list_length(rtable) < 2)
 		return;
 
+	/*
+	 * If it's the parent of an inheritance tree, ignore its FKs.  We could
+	 * make useful FK-based deductions if we found that all members of the
+	 * inheritance tree have equivalent FK constraints, but detecting that
+	 * would require code that hasn't been written.
+	 */
+	if (inhparent)
+		return;
+
 	/*
 	 * Extract data about relation's FKs from the relcache.  Note that this
 	 * list belongs to the relcache and might disappear in a cache flush, so
@@ -488,6 +497,9 @@ get_relation_foreign_keys(PlannerInfo *root, RelOptInfo *rel,
 			if (rte->rtekind != RTE_RELATION ||
 				rte->relid != cachedfk->confrelid)
 				continue;
+			/* Ignore if it's an inheritance parent; doesn't really match */
+			if (rte->inh)
+				continue;
 			/* Ignore self-referential FKs; we only care about joins */
 			if (rti == rel->relid)
 				continue;