Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> writes:
>> So some changing-oid operations like vacuum full, reindex, etc will not
>> affect these system catalogs?
> Is it possible to cluster system tables?
No, and yes. CLUSTER, REINDEX, and similar things change the
relfilenode, not the relation OID.
If you are looking for things that will fundamentally break the system,
try renaming one of the indexes of a core system catalog ;-). We could
avoid that dependency if we went by OIDs instead.
regards, tom lane