Oracle Deadlock Query and processing

Select Bs.username "Blocking user", bs.username "DB user",
Ws.username "Waiting User", BS. Sid "Sid", WS. SID "Wsid",
bs.serial# "serial#", bs.sql_address "address",
Bs.sql_hash_value "SQL Hash", bs.program "Blocking App",
Ws.program "Waiting App", bs.machine "Blocking machine",
Ws.machine "Waiting Machine", Bs.osuser "Blocking OS User",
Ws.osuser "Waiting OS User", bs.serial# "serial#",
ws.serial# "wserial#",
DECODE (wk. 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 ',
Wk. TYPE
) Lock_type,
DECODE (Hk.lmode,
0, ' None ',
1, ' NULL ',
2, ' Row-s (SS) ',
3, ' Row-x (SX) ',
4, ' SHARE ',
5, ' S/row-x (SSX) ',
6, ' EXCLUSIVE ',
To_char (Hk.lmode)
) Mode_held,
DECODE (Wk.request,
0, ' None ',
1, ' NULL ',
2, ' Row-s (SS) ',
3, ' Row-x (SX) ',
4, ' SHARE ',
5, ' S/row-x (SSX) ',
6, ' EXCLUSIVE ',
To_char (Wk.request)
) mode_requested,
To_char (HK.ID1) lock_id1, To_char (HK.ID2) Lock_id2,
DECODE
(HK. BLOCK,
0, ' not Blocking ',/**//* not Blocking any other processes */
1, ' Blocking ',/**//* this lock blocks other processes */
2, ' Global ',/**//* this lock are Global, so we can ' t tell */
To_char (HK). BLOCK)
) blocking_others
From V$lock HK, v$session BS, V$lock wk, v$session ws
WHERE HK. BLOCK = 1
and Hk.lmode! = 0
and Hk.lmode! = 1
and wk.request! = 0
and WK. TYPE (+) = HK. TYPE
and WK.ID1 (+) = Hk.id1
and Wk.id2 (+) = Hk.id2
and HK. SID = BS. SID (+)
and WK. SID = ws. SID (+)
and (Bs.username is not NULL)
and (Bs.username <> ' SYSTEM ')
and (Bs.username <> ' SYS ')
ORDER by 1;

--------------------------------------------------------------------------------
Query the SELECT statement that a deadlock occurred

Select Sql_text from V$sql where Hash_value in
(select Sql_hash_value from v$session where SID in
(select session_id from V$locked_object))

---------------------------------------------------------
How to check database deadlock

I.          database deadlock phenomenon
during the execution of the program, click OK or save button, the program does not respond, there is no error.
Second, the principle of          deadlock
When you perform an update or delete operation on a column of a table in a database, the statement does not mention the
intersection, Another statement for this column of data to do the update operation will be in the waiting state,
The phenomenon is that this statement has been executing, but has not executed successfully, and no error.
Three,          location method of deadlock
by examining the database table, you can check which statement is deadlocked, which is the machine that generated the deadlock.
1) Execute the following statement with the DBA user
Select Username,lockwait,status,machine,program from v$session where SID in
(select Session_ ID from V$locked_object)
If there is a result of the output, it indicates which machine is deadlocked and which one can see the deadlock. Field Description:
Username: The database user used by the deadlock statement;
Lockwait: The state of the deadlock if there is a content representation being deadlocked.
Status: State, active represents deadlock
Machine: The machines where the deadlock statement resides.
Program: The main application from which the statement that generated the deadlock came from.
2) You can view the deadlock statement by executing the following statement with the DBA user.
Select Sql_text from V$sql where Hash_value in ,
(select Sql_hash_value from v$session where SID in
(select session_id from V$locked_object))

Iv. methods of deadlock resolution
In general, as long as the statement that produces the deadlock is committed, but in the actual execution. Users can
It is not known which sentence to generate a deadlock. You can shut down the program and restart it.
Often encountered this problem in the use of Oracle, so also summed up a little solution.

1) To find the deadlock process:

Sqlplus "/as sysdba" (Sys/change_on_install)
SELECT s.username,l.object_id,l.session_id,s.serial#,
L.oracle_username,l.os_user_name,l.process
From V$locked_object l,v$session S WHERE l.session_id=s.sid;

2) Kill the deadlock process:

Alter system kill session ' sid,serial# '; (where sid=l.session_id)

3) If it is not resolved:

Select Pro.spid from v$session ses,
V$process Pro where ses.sid=xx and
SES.PADDR=PRO.ADDR;

Where SID is replaced with a dead-lock SID:

Exit
Ps-ef|grep spid

Where SPID is the process number of this process, kill the Oracle process.

Oracle Deadlock Query and processing