Oracle动态视图v$active_session_history实战示例

a.应用场景：开发反应2023-03-02 00:22至00:35，数据落盘慢，根据情况查看此时间段的主要活动事件，数量，与sql_id（全局）
select count(*), sql_id, event, blocking_session
  from gv$active_session_history
 where sample_time between
       to_date('2023-03-02 00:22:00', 'yyyy-mm-dd hh24:mi:ss') and
       to_date('2023-03-02 00:35:00', 'yyyy-mm-dd hh24:mi:ss')
 group by sql_id, event, blocking_session
 order by 1;
（非全局）BLOCKING_INST_ID--被阻塞者, blocking_session--阻塞者
select count(*), sql_id, event, BLOCKING_INST_ID, blocking_session
  from v$active_session_history
 where sample_time between
       to_date('2023-03-02 00:20:00', 'yyyy-mm-dd hh24:mi:ss') and
       to_date('2023-03-02 00:35:00', 'yyyy-mm-dd hh24:mi:ss')
 group by sql_id, event, BLOCKING_INST_ID, blocking_session
 order by 1;
b.现在我们已经得到两个关键信息：sql_id与阻塞事件,首先根据sql_id我们可以再进一步使用此视图，实际中可以多调整几个较小的时间段，以突出最有代表的信息
select count(*),
       session_id,
       session_serial#,
       sql_id,
       event,
       BLOCKING_INST_ID,
       blocking_session
  from v$active_session_history
 where sample_time between
       to_date('2023-03-02 00:24:00', 'yyyy-mm-dd hh24:mi:ss') and
       to_date('2023-03-02 00:25:00', 'yyyy-mm-dd hh24:mi:ss')
   and sql_id = '1xfbtdvu3xb67'
 group by session_id,
          session_serial#,
          sql_id,
          event,
          BLOCKING_INST_ID,
          blocking_session
 order by 3;
c.加入等待事件后更清晰
select count(*),
       session_id,
       sql_id,
       event,
       BLOCKING_INST_ID,
       blocking_session
  from v$active_session_history
 where sample_time between
       to_date('2023-03-02 00:25:00', 'yyyy-mm-dd hh24:mi:ss') and
       to_date('2023-03-02 00:35:00', 'yyyy-mm-dd hh24:mi:ss')
   and event = 'library cache lock'
   and sql_id = '1j47z0mc6k02b'
 group by session_id, sql_id, event, BLOCKING_INST_ID, blocking_session
 order by 1;
结论：可以看出大量并发等待，最终是发现有什么阻塞了此SQL语句

#根据dba_objects确定创建时间是否匹配
select owner,
       object_name,
       object_type,
       to_char(created, 'yyyy-mm-dd hh24:mi:ss')
  from dba_objects
 where object_name = 'AA_BBB_CCCC_DDDD_OUT'
   and created > to_date('2023-03-01', 'yyyy-mm-dd')
 order by 4;
 select owner,
       object_name,
       object_type,
       to_char(created, 'yyyy-mm-dd hh24:mi:ss')
  from dba_objects
 where object_name = 'AA_BBB_CCCC_DDDD_IN'
   and created > to_date('2023-03-01', 'yyyy-mm-dd')
 order by 4;