版本12c中引入了dbms_stats 的一系列report_*  函数，用以在收集统计信息前 向用户汇报预备将执行的统计对象和统计情况。   例如report_gather_auto_stats   function report_gather_auto_stats ( detail_level varchar2 default 'TYPICAL', format varchar2 default 'TEXT') return clob; -- -- This procedure runs auto stats gathering job in reporting mode. That is, -- stats are not actually collected, but all the objects that will be -- affected when auto stats gathering is invoked are reported. -- The detail level for the report is defined by the detail_level -- input parameter. Please see the comments for report_single_stats_operation -- on possible values for detail_level and format.   具体使用：   SQL> variable c clob; SQL> exec :c:=dbms_stats.report_gather_auto_stats(); PL/SQL procedure successfully completed. SQL> set long 999   SQL> print :c; C -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- --------------------------------------- | Id | Operation | Target | Start Time | E nd Time | Status | Total Tasks | Successful Tasks | Failed Tasks | Active Tasks | -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- --------------------------------------- | 1317 | gather_database_stats (auto) (reporting mode) | AUTO | | | | 187 | | | | -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- --------------------------------------- -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- --------------------------------------- | | | ------------------------------------------------------------------------------ -------------------------------------------------------------------------------- ------------------------------------- | | T A S K S | | ------------------------------------------------------------------------------ -------------------------------------------------------------------------------- ------------------------------------- | | --------------------------------------------------------------------------- -------------------------------------------------------------------------------- ---------------------------------- | | | Target | Type | Start Tim e | End Time | Status | | | --------------------------------------------------------------------------- -------------------------------------------------------------------------------- ---------------------------------- | | | SYS.BBW | TABLE |