gather fixed objects stats - cheeyoung/sqlplus-public GitHub Wiki

SQL> dbms_stats.gather_fixed_objects_stats ;

13.3.5 Gathering Statistics for Fixed Objects

Fixed objects are dynamic performance tables and their indexes. These objects record current database activity.
Unlike other database tables, the database does not automatically use dynamic statistics for SQL statement referencing X$ tables when optimizer statistics are missing. Instead, the optimizer uses predefined default values. These defaults may not be representative and could potentially lead to a suboptimal execution plan. Thus, it is important to keep fixed object statistics current.