How to see Database locks.


1- Check if one session is locking to another session.

 select s1.username || '@' || s1.machine
|| ' ( SID=' || s1.sid || ' ) is blocking '
|| s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status,
'ALTER SYSTEM KILL SESSION ' || chr(39) || s1.sid || ',' || s1.serial# || chr(39) || ' IMMEDIATE;' AS KILL
from v$lock l1, v$session s1, v$lock l2, v$session s2
where s1.sid=l1.sid and s2.sid=l2.sid
and l1.BLOCK=1 and l2.request > 0
and l1.id1 = l2.id1
and l2.id2 = l2.id2 ;



2- See locked object and lock type.

select    oracle_username || ' (' || s.osuser || ')' username
,    s.sid || ',' || s.serial# sess_id
,    owner || '.' ||    object_name object
,    object_type
,    decode(    l.block
    ,    0, 'Not Blocking'
    ,    1, 'Blocking'
    ,    2, 'Global') status
,    decode(v.locked_mode
    ,    0, 'None'
    ,    1, 'Null'
    ,    2, 'Row-S (SS)'
    ,    3, 'Row-X (SX)'
    ,    4, 'Share'
    ,    5, 'S/Row-X (SSX)'
    ,    6, 'Exclusive', TO_CHAR(lmode)) mode_held
from    v$locked_object v
,    dba_objects d
,    v$lock l
,    v$session s
where     v.object_id = d.object_id
and     v.object_id = l.id1
and     v.session_id = s.sid
order by oracle_username
,    session_id
/


0 = none
1 = null
2 = Row- Share
3 = Row- exclusive
4 = Share
5 = Share /Row- exclusive
6 = exclusive

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