diff --git a/src/backend/utils/cache/partcache.c b/src/backend/utils/cache/partcache.c
index 3107075c9ad6..b25751b3793f 100644
--- a/src/backend/utils/cache/partcache.c
+++ b/src/backend/utils/cache/partcache.c
@@ -404,21 +404,28 @@ generate_partition_qual(Relation rel)
 	/*
 	 * Save a copy in the relcache.  The order of these operations is fairly
 	 * critical to avoid memory leaks and ensure that we don't leave a corrupt
-	 * relcache entry if we fail partway through copyObject.
+	 * relcache entry if we fail partway through copyObject.  rd_partcheckcxt
+	 * and rd_partcheck are assigned last, after copyObject() succeeds.
 	 *
 	 * If, as is definitely possible, the partcheck list is NIL, then we do
 	 * not need to make a context to hold it.
 	 */
 	if (result != NIL)
 	{
-		rel->rd_partcheckcxt = AllocSetContextCreate(CacheMemoryContext,
-													 "partition constraint",
-													 ALLOCSET_SMALL_SIZES);
-		MemoryContextCopyAndSetIdentifier(rel->rd_partcheckcxt,
+		MemoryContext partcheckcxt;
+		List	   *partcheck;
+
+		partcheckcxt = AllocSetContextCreate(CacheMemoryContext,
+											 "partition constraint",
+											 ALLOCSET_SMALL_SIZES);
+		MemoryContextCopyAndSetIdentifier(partcheckcxt,
 										  RelationGetRelationName(rel));
-		oldcxt = MemoryContextSwitchTo(rel->rd_partcheckcxt);
-		rel->rd_partcheck = copyObject(result);
+		oldcxt = MemoryContextSwitchTo(partcheckcxt);
+		partcheck = copyObject(result);
 		MemoryContextSwitchTo(oldcxt);
+
+		rel->rd_partcheckcxt = partcheckcxt;
+		rel->rd_partcheck = partcheck;
 	}
 	else
 		rel->rd_partcheck = NIL;