Function GetUserNameFromId

src/backend/utils/init/miscinit.c:953–974

* Get user name from user oid, returns NULL for nonexistent roleid if noerr * is true. */

 * is true.
 */
char *
GetUserNameFromId(Oid roleid, bool noerr)
{
	HeapTuple	tuple;
	char	   *result;

	tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
	if (!HeapTupleIsValid(tuple))
	{
		if (!noerr)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("invalid role OID: %u", roleid)));
		result = NULL;
	}
	else
	{
		result = pstrdup(NameStr(((Form_pg_authid) GETSTRUCT(tuple))->rolname));
		ReleaseSysCache(tuple);
	}
	return result;
}

Oid
GetCurrentWarehouseId(void)