ALTER LANGUAGE RENAME has never worked. Per Sergey Yatskevich.

diff --git a/src/backend/commands/proclang.c b/src/backend/commands/proclang.c
index 3b264373f8496f41f887c87b20a0403e71563e1e..1b0ed369631a28e9106fb736eac3d58ac3bae6cb 100644 (file)
--- a/src/backend/commands/proclang.c
+++ b/src/backend/commands/proclang.c
@@ -246,7 +246,7 @@ RenameLanguage(const char *oldname, const char *newname)
        HeapTuple       tup;
        Relation        rel;
 
-       rel = heap_openr(ShadowRelationName, RowExclusiveLock);
+       rel = heap_openr(LanguageRelationName, RowExclusiveLock);
 
        tup = SearchSysCacheCopy(LANGNAME,
                                                         CStringGetDatum(oldname),