Recipie #1 - find blocking sessions with v$session
SELECT
s.blocking_session,
s.sid,
s.serial#,
s.seconds_in_wait
FROM
v$session s
WHERE
blocking_session IS NOT NULL;
Recipie #2 - find blocking sessions using v$lock
SELECT
l1.sid || ' is blocking ' || l2.sid blocking_sessions
FROM
v$lock l1, v$lock l2
WHERE
l1.block = 1 AND
l2.request > 0 AND
l1.id1 = l2.id1 AND
l1.id2 = l2.id2;
SELECT
l1.sid || ' is blocking ' || l2.sid blocking_sessions
FROM
gv$lock l1, gv$lock l2
WHERE
l1.block = 1 AND
l2.request > 0 AND
l1.id1 = l2.id1 AND
l1.id2 = l2.id2;
Recipie #3 - blocking sessions with all available information
The next query prints a few more information, it let's you quickly see who's blocking who.
Run this query and you can immediately call the colleague who's locking your table:
SELECT s1.username || '@' || s1.machine
|| ' ( SID=' || s1.sid || ' ) is blocking '
|| s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status
FROM v$lock l1, v$session s1, v$lock l2, v$session s2
WHERE s1.sid=l1.sid AND s2.sid=l2.sid
AND l1.BLOCK=1 AND l2.request > 0
AND l1.id1 = l2.id1
AND l2.id2 = l2.id2 ;
Locks:
SET PAGESIZE 14
SET VERIFY ON
SET LINESIZE 500
SET PAGESIZE 1000
SET VERIFY OFF
COLUMN owner FORMAT A20
COLUMN username FORMAT A20
COLUMN object_owner FORMAT A20
COLUMN object_name FORMAT A30
COLUMN locked_mode FORMAT A15
SELECT b.session_id AS sid,
NVL(b.oracle_username, '(oracle)') AS username,
a.owner AS object_owner,
a.object_name,
Decode(b.locked_mode, 0, 'None',
1, 'Null (NULL)',
2, 'Row-S (SS)',
3, 'Row-X (SX)',
4, 'Share (S)',
5, 'S/Row-X (SSX)',
6, 'Exclusive (X)',
b.locked_mode) locked_mode,
b.os_user_name
FROM dba_objects a,
gv$locked_object b
WHERE a.object_id = b.object_id
ORDER BY 1, 2, 3, 4;
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