Locking or unlocking table statistics.

In certain cases you may want to lock statistics in a table in certain cases, for example if you want a table not be analyzed by automatic statistics job but analyze it later or in cases where you want prevent from analyzing statistics in cases where data in the table doesn’t change.

The following example shows how to lock table statistics and what happens when one tries to gather statistics on table that has statistics locked.

• create table

  SQL> create table test ( x number );

  Table created. 
   

• Create index

  SQL> create index test_idx on test(x);

  Index created.
   

• When stats is not locked the value of stattype_locked is NULL

  SQL> SELECT stattype_locked FROM dba_tab_statistics WHERE table_name = 'TEST' and owner = 'SCOTT';

  STATT
  -----

• Locking the table statistics

  SQL> exec dbms_stats.lock_table_stats('scott', 'test');

  PL/SQL procedure successfully completed.

• When stats is locked the value of stattype_locked is ALL

  SQL> SELECT stattype_locked FROM dba_tab_statistics WHERE table_name = 'TEST' and owner = 'SCOTT';

  STATT
  -----
  ALL

•  Try to gather statistics on locked table

  SQL> exec dbms_stats.gather_index_stats('scott', 'test_idx');

  BEGIN dbms_stats.gather_index_stats('scott', 'test_idx'); END;
  *
  ERROR at line 1:
  ORA-20005: object statistics are locked (stattype = ALL)
  ORA-06512: at “SYS.DBMS_STATS”, line 10640
  ORA-06512: at “SYS.DBMS_STATS”, line 10664
  ORA-06512: at line 1

• try to gather statistics on the index using analyze

  SQL> analyze index ajaffer.test_idx compute statistics;

  analyze index ajaffer.test_idx compute statistics
  *
  ERROR at line 1: ORA-38029: object statistics are locked
   

• unlock statistics

  SQL> exec dbms_stats.unlock_table_stats('scott', 'test');

  PL/SQL procedure successfully completed.