Optimizer Statistics - Views

To Check when the object's statistics was last gathered

SQL> Select last_analyzed, table_name, owner, num_rows, sample_size
From dba_tables
Order By last_analyzed;

To check the statistics gathered on the tables

SQL> Select * From DBA_TAB_STATISTICS;

To check the statistics gathered on Columns

SQL> Select * From DBA_TAB_COL_STATISTICS;

To check the amount of DML operations on tables

SQL> Select * From SYS.DBA_TAB_MODIFICATIONS;

Thanks