Oracle動態檢視v$active_session_history實戰範例

a.應用場景：開發反應2023-03-02 00:22至00:35，資料落盤慢，根據情況檢視此時間段的主要活動事件，數量，與sql_id（全域性）
select count(*), sql_id, event, blocking_session
  from gv$active_session_history
 where sample_time between
       to_date('2023-03-02 00:22:00', 'yyyy-mm-dd hh24:mi:ss') and
       to_date('2023-03-02 00:35:00', 'yyyy-mm-dd hh24:mi:ss')
 group by sql_id, event, blocking_session
 order by 1;
（非全域性）BLOCKING_INST_ID--被阻塞者, blocking_session--阻塞者
select count(*), sql_id, event, BLOCKING_INST_ID, blocking_session
  from v$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.現在我們已經得到兩個關鍵資訊：sql_id與阻塞事件,首先根據sql_id我們可以再進一步使用此檢視，實際中可以多調整幾個較小的時間段，以突出最有代表的資訊
select count(*),
       session_id,
       session_serial#,
       sql_id,
       event,
       BLOCKING_INST_ID,
       blocking_session
  from v$active_session_history
 where sample_time between
       to_date('2023-03-02 00:24:00', 'yyyy-mm-dd hh24:mi:ss') and
       to_date('2023-03-02 00:25:00', 'yyyy-mm-dd hh24:mi:ss')
   and sql_id = '1xfbtdvu3xb67'
 group by session_id,
          session_serial#,
          sql_id,
          event,
          BLOCKING_INST_ID,
          blocking_session
 order by 3;
c.加入等待事件後更清晰
select count(*),
       session_id,
       sql_id,
       event,
       BLOCKING_INST_ID,
       blocking_session
  from v$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;
結論：可以看出大量並行等待，最終是發現有什麼阻塞了此SQL語句

#根據dba_objects確定建立時間是否匹配
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;