How do we gather optimizer statistics?

How do we gather optimizer statistics?

* By default, Oracle Database uses automatic optimizer statistics collection

* Database automatically runs DBMS_STATS to collect optimizer statistics for all schema objects for which statistics are missing or stale

* You can also update and manage optimizer statistics by manually executing DBMS_STATS

* Also, when optimizer statistics are missing, stale, or insufficient, the database automatically gathers dynamic statistics during a parse (depends on level of dynamic sampling)