Summary
Oracle Real Application Cluster Database may have two or more instances, so monitoring the blocking sessions from one instances is a little bit tricky.
You
cannot use the script:
blocking sessions for single instance
Especially for RAC databases use:
SELECT b.inst_id,LPAD('--->',DECODE(A.request,0,0,5))||A.SID SID, a.id1, a.id2, a.lmode, a.BLOCK, a.request,
DECODE(a.TYPE,
'MR', 'Media Recovery',
'RT', 'Redo Thread',
'UN', 'User Name',
'TX', 'Transaction',
'TM', 'DML',
'UL', 'PL/SQL User Lock',
'DX', 'Distributed Xaction',
'CF', 'Control File',
'IS', 'Instance State',
'FS', 'File Set',
'IR', 'Instance Recovery',
'ST', 'Disk Space Transaction',
'TS', 'Temp Segment',
'IV', 'Library Cache Invalidation',
'LS', 'Log Start or Switch',
'RW', 'Row Wait',
'SQ', 'Sequence Number',
'TE', 'Extend Table',
'TT', 'Temp Table', a.TYPE) lock_type,
b.PROGRAM,b.OSUSER ,b.USERNAME,b.status, b.module,b.action ,b.LOGON_TIME,b.LAST_CALL_ET,
'alter system kill session ' || '''' || a.SID || ', ' || b.serial# ||'''' || ' immediate;' kill_session,
DECODE(object_type, NULL, NULL, 'Dbms_Rowid.rowid_create(1, ' || row_wait_obj# || ', '
|| row_wait_file# ||', ' || row_wait_block#||', ' || row_wait_row# ||')') row_id
FROM gV$LOCK a, gv$session b, dba_objects o
WHERE (a.id1,a.id2) IN (SELECT id1,id2 FROM gV$LOCK WHERE lmode=0)
AND a.INST_ID=b.INST_ID
AND a.SID=b.SID
AND o.object_id (+) = DECODE(b.ROW_WAIT_OBJ#, -1, NULL, b.ROW_WAIT_OBJ#)
ORDER BY a.id1,a.id2,a.request;
Tip: If the column BLOCK=2, 'Global' then this lock is global, it comes from the other instance!
