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.GT16435@telsasoft.com

diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index 07e5e78caa8fc935dd1839d1e182bedbffa962e7..aa4bc5719593955c458c52a6dc9764dad0582e8e 100644 (file)
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -921,7 +921,11 @@ 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);