Ensure pg_filenode_relation(0, 0) returns NULL.

Previously, a zero value for the relfilenode resulted in
a confusing error message about "unexpected duplicate".
This function returns NULL for other invalid relfilenode
values, so zero should be treated likewise.

It's been like this all along, so back-patch to all supported
branches.

Justin Pryzby

Discussion: https://postgr.es/m/20210612023324[email protected]

diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index 74cdbb055100693711ae42872e2e5108237bddba..2227ccc2c4560b76add4727c782e223bcaa91241 100644 (file)
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -919,7 +919,11 @@ pg_filenode_relation(PG_FUNCTION_ARGS)
 {
    Oid         reltablespace = PG_GETARG_OID(0);
    Oid         relfilenode = PG_GETARG_OID(1);
-   Oid         heaprel = InvalidOid;
+   Oid         heaprel;
+
+   /* test needed so RelidByRelfilenode doesn't misbehave */
+   if (!OidIsValid(relfilenode))
+       PG_RETURN_NULL();
 
    heaprel = RelidByRelfilenode(reltablespace, relfilenode);