概述

国庆节偷个懒，分享一个关于锁的实用sql,不过统计是实时的，如果要查看一段时间的，建议将结果插入一张中间表。

一键获取锁相关信息

SELECT mm.inst_id,  mm.sid,  mm.TYPE,  mm.id1,  mm.id2,  LPAD(TRUNC(mm.ctime / 60 / 60), 3) || ' Hour ' || LPAD(TO_CHAR(TRUNC(mm.ctime / 60) - TRUNC(mm.ctime / 60 / 60) * 60, 'fm09'), 2) || ' Min ' || LPAD(TO_CHAR(mm.ctime - TRUNC(mm.ctime / 60) * 60, 'fm09'), 2) || ' Sec' ctime,  CASE WHEN mm.block = 1  AND mm.lmode != 0 THEN 'holder'  WHEN mm.block = 0  AND mm.request != 0 THEN 'waiter'  ELSE NULL END role,  CASE WHEN ee.blocking_session IS NOT NULL THEN 'waiting for SID ' || ee.blocking_session  ELSE NULL END blocking_session,  dd.sql_text sql_text,  cc.event wait_event  FROM gv$lock mm,  gv$session ee,  gv$sqlarea dd,  gv$session_wait cc  WHERE mm.sid IN (SELECT nn.sid  FROM (SELECT tt.*,  COUNT(1) OVER (PARTITION BY tt.TYPE,  tt.id1,  tt.id2) cnt, MAX(tt.lmode) OVER (PARTITION BY tt.TYPE,  tt.id1,  tt.id2) lmod_flag, MAX(tt.request) OVER (PARTITION BY tt.TYPE,  tt.id1,  tt.id2) request_flag  FROM gv$lock tt) nn  WHERE nn.cnt > 1  AND nn.lmod_flag != 0  AND nn.request_flag != 0)  AND mm.sid = ee.sid (+)  AND ee.sql_id = dd.sql_id (+)  AND mm.sid = cc.sid (+)  AND ((mm.block = 1  AND mm.lmode != 0)  OR (mm.block = 0  AND mm.request != 0))  ORDER BY mm.TYPE, mm.id1, mm.id2, mm.lmode DESC,  mm.ctime DESC

通过这条sql我们可以看到哪个事务被哪个事务所阻塞了，阻塞了多久及相关的sql。

优化后的sql

以下是对上面sql的进一步优化：

SELECT /*+ NO_CPU_COSTING */ mm.inst_id,  mm.sid,  mm.TYPE,  mm.id1,  mm.id2,  LPAD(TRUNC(mm.ctime / 60 / 60), 3) || ' Hour ' || LPAD(TO_CHAR(TRUNC(mm.ctime / 60) - TRUNC(mm.ctime / 60 / 60) * 60, 'fm09'), 2) || ' Min ' || LPAD(TO_CHAR(mm.ctime - TRUNC(mm.ctime / 60) * 60, 'fm09'), 2) || ' Sec' ctime,  CASE WHEN mm.block = 1  AND mm.lmode != 0 THEN 'holder'  WHEN mm.block = 0  AND mm.request != 0 THEN 'waiter'  ELSE NULL END role,  CASE WHEN ee.blocking_session IS NOT NULL THEN 'waiting for SID ' || ee.blocking_session  ELSE NULL END blocking_session,  dd.sql_text sql_text,  cc.event wait_event  FROM gv$lock mm,  gv$session ee,  gv$sqlarea dd,  gv$session_wait cc  WHERE EXISTS (SELECT 'X'  FROM (SELECT tt.*,  COUNT(1) OVER (PARTITION BY tt.TYPE,  tt.id1,  tt.id2) cnt, MAX(tt.lmode) OVER (PARTITION BY tt.TYPE,  tt.id1,  tt.id2) lmod_flag, MAX(tt.request) OVER (PARTITION BY tt.TYPE,  tt.id1,  tt.id2) request_flag  FROM gv$lock tt) nn  WHERE nn.cnt > 1  AND nn.lmod_flag != 0  AND nn.request_flag != 0  AND nn.sid = mm.sid)  AND mm.sid = ee.sid (+)  AND ee.sql_id = dd.sql_id (+)  AND mm.sid = cc.sid (+)  AND (mm.block = 1  AND mm.lmode <> 0  OR mm.block = 0  AND mm.request <> 0)  ORDER BY mm.TYPE, mm.id1, mm.id2, mm.lmode DESC,  mm.ctime DESC

查看阻塞会话SID信息(holder)

--查看阻塞会话SID信息(holder)--考虑到多实例会存在sid一致的情况，所以加了实例区分SELECT INST_ID "实例ID