PLSQL_统计信息系列06_统计信息的历史和日志

select dbms_stats.get_stats_history_retention() as retention
from dual;

dbms_stats.alter_stats_history_retention(retention => 31); 

dbms_stats.purge_stats(before_timestamp => systimestamp-31);

select stats_update_time
  from dba_tab_stats_history
 where owner = 'SYS'
   and table_name = 'WRH$_SYSSTAT'

dbms_stats.restore_schema_stats(ownname => 'SH',
                                as_of_imestamp => systimestamp-1,
                                force => TRUE)

select operation,
       start_time,
       (end_time - start_time) day(1) to second(0) as duration
  from dba_optstat_operations
 order by start_time desc;