diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 9e14880b99..4319fc6b8c 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -1772,6 +1772,8 @@ heap_drop_with_catalog(Oid relid)
 	 * shared-cache-inval notice that will make them update their index lists.
 	 */
 	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation %u", relid);
 	if (((Form_pg_class) GETSTRUCT(tuple))->relispartition)
 	{
 		parentOid = get_partition_parent(relid);
@@ -3131,9 +3133,6 @@ StorePartitionKey(Relation rel,
 
 	Assert(rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
-	tuple = SearchSysCache1(PARTRELID,
-							ObjectIdGetDatum(RelationGetRelid(rel)));
-
 	/* Copy the partition attribute numbers, opclass OIDs into arrays */
 	partattrs_vec = buildint2vector(partattrs, partnatts);
 	partopclass_vec = buildoidvector(partopclass, partnatts);
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d19846d005..d979ce266d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -14111,6 +14111,9 @@ ATExecDetachPartition(Relation rel, RangeVar *name)
 	classRel = heap_open(RelationRelationId, RowExclusiveLock);
 	tuple = SearchSysCacheCopy1(RELOID,
 								ObjectIdGetDatum(RelationGetRelid(partRel)));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation %u",
+			 RelationGetRelid(partRel));
 	Assert(((Form_pg_class) GETSTRUCT(tuple))->relispartition);
 
 	(void) SysCacheGetAttr(RELOID, tuple, Anum_pg_class_relpartbound,