@@header

/*

Author   : Vishal Gupta
Purpose  : Displays blocking locks in database

*  Revision History:
*  ===================
*  Date       Author        Description
*  ---------  ------------  -----------------------------------------
*  27-Feb-12  Vishal Gupta  Intial version
*  18-Apr-12  Vishal Gupta  Replace with gv$session with materialize hinted
*                           sub-query factoring (CTE - common table extression)
*
*/

COLUMN INST_ID                        HEADING "I#"                          FORMAT 99
COLUMN SID                                                                  FORMAT a20
COLUMN username                       HEADING "UserName"                    FORMAT a20 TRUNC
COLUMN lock_type                      HEADING "Lock|type"                   FORMAT a4  TRUNC
COLUMN lock_Name                      HEADING "Lock Name"                   FORMAT a22 TRUNC 
COLUMN osuser                         HEADING "OSUser"                      FORMAT a20 TRUNC
COLUMN machine                        HEADING "Client|Machine"              FORMAT a20 TRUNC 
COLUMN blocking_instance              HEADING "Bl'ing|Inst"         
COLUMN blocking_session               HEADING "Bl'ing|SID"
COLUMN blocking_session_status        HEADING "Bl'ing|Session|Status"
COLUMN final_blocking_instance        HEADING "Final|Bl'ing|Inst"
COLUMN final_blocking_session         HEADING "Final|Bl'ing|SID" 
COLUMN final_blocking_session_status  HEADING "Final|Bl'ing|Session|Status"
COLUMN program                        HEADING "Program"                     FORMAT a30 TRUNC
COLUMN event                          HEADING "Event"                       FORMAT a30 TRUNC


-- Materialize hint is needed to speed up the joins 
-- between dynamic performance view gv$session
 
-- Need to use Subquery for gv$session, otherwise session is disconnect with ORA-07445 [qksopCheckPropOpt]
WITH  sess as 
  ( select /*+ materialize */  s1.* from gv$session s1
  )
, locks as
(select /*+ materialize */ * from gv$lock where lmode = 0 
 -- AND ( l.lmode = 0 OR  (l.lmode > 0 AND l.block > 0))
)
SELECT  s.inst_id
     , DECODE(level
           ,1 , s.sid || ' (Blocker)'    
     , ' ' || LPAD('-',(level-1)*4,'|---') || '> ' || s.sid 
     ) 
    -- || NVL2(s2.blocking_session, ' (Blocker)', ' ')
    sid
     , s.status
--  , l.lmode
--  , l.request
--  , l.block
--  , s.lock_type
  , lt.name lock_name
     , s.username
     , s.osuser
     , s.sql_id
     , s.program
     , s.event
--     , s.blocking_instance
--     , s.blocking_session
--     , s.blocking_session_status
--     , s.final_blocking_instance
--     , s.final_blocking_session
--     , s.final_blocking_session_status
FROM  sess s
   LEFT OUTER JOIN sess s2 ON  s2.blocking_instance = s.inst_id AND s2.blocking_session = s.sid
      LEFT OUTER JOIN locks l ON  l.inst_id = s.inst_id
                         AND l.sid     = s.sid 
   LEFT OUTER JOIN v$lock_type lt ON l.type  = lt.type 
WHERE 
(
s.blocking_session IS NOT NULL
OR s2.sid IS NOT NULL
)
CONNECT BY PRIOR s.inst_id = s.blocking_instance
       AND PRIOR s.sid     = s.blocking_session
START WITH s.blocking_session IS NULL
;

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