OOUG: Oracle transaction locking

Enqueue Waits : Locks
Thanks to Doug Burns for much of the
Row Lock example
Kyle Hailey
Kylehailey.com
kyle@delphix.com

Content
Part I : Row Locks
– enq: TX - row lock contention
•
•
•
•
•

Data in ASH
OEM
V$lock & v$session
ASH
Find blocking SQL

Part II : Row Locks ??
– enq: TX - row lock contention, mode 4

Part III : Other TX locks
–
–
–

enq: TX - allocate ITL entry
enq: TX - index contention
enq: TX – contention

Part IV : TM locks

Lock Types
•

9i
– One Wait : “enqueue”

•

10g

TX
TM
Transaction Table Modification

– 208 enqueue waits
– Specific to each type of enqueue
– select name,wait_class from v$event_name where name like 'enq%'
enq:
enq:
enq:
enq:
enq:
enq:
enq:
enq:
enq:
enq:

HW
SQ
SS
ST
TM
TW
TX
TX
TX
TX

–

contention
contention
contention
contention
contention
contention
allocate ITL entry
index contention
row lock contention
contention

Configuration
Configuration
Configuration
Configuration
Application
Administrative
Configuration
Concurrency
Application
Application

Lock Modes
# Type
--- ------1 Null
2 SS
3 SX
4 S
5 SSX
6 X

Name
--------------------------Null
Sub share
Sub exclusive
Share
Share/sub exclusive
Exclusive

Lock Type and Mode
Select parameter1 from v$event_name where name like ‘enq%’;
Parameter1
---------Name|mode
Select p1, p1raw from v$session where event like 'enq%';

P1
P1RAW
---------- -------1415053318 54580006

Name: 5458
Hex
Decimal
54 =
84
58 =
88

ASCII
=
“T”
=
“X”

Mode: 0006
Lock = TX 6

Type and Mode
SELECT
SELECT
chr(bitand(p1,-16777216)/16777215)||
chr(bitand(p1,-16777216)/16777215)||
chr(bitand(p1, 16711680)/65535)
chr(bitand(p1, 16711680)/65535)
TYPE,
TYPE,
mod(p1,16)
LMODE
mod(p1,16)
LMODE
from v$session
from v$session
where event like ‘enq%’;
where event like ‘enq%’;
TY
LMODE
TY
LMODE
-- ----------- ---------TX
6
TX
6

enq: TX - row lock contention, mode 6
To Solve we need:

1. Waiter
2. Blocker
3. Blocking Object
4. Lock Type
– type
– mode

Missing : blocking SQL
– Possibly with log miner

OEM 10g

if P1 = 1415053318
then mode = 6
Then it is a data block
row lock

enq: TX - row lock contention
Mode 6, row in data block
User 1
SQL> delete from toto
where id = 1;

User 2

SQL> delete from toto
where id =1;
Table
ID
Value
foo
1

Power of ASH :
v$active_session_history
•

•

Waiter
– SESSION_ID
– SESSION_SERIAL#
– USER_ID
Object
– CURRENT_OBJ#
– CURRENT_FILE#
– CURRENT_BLOCK#

•

SQL Waiting
-

•

SQL_ID

Blocker
-

•

BLOCKING_SESSION
BLOCKING_SESSION_STATUS

- BLOCKING_SESSION_SERIAL#
Lock Type and Mode
- Event = Type (name)
- P1
= Type | Mode

Missing: Blocking SQL !

Querying ASH
select
substr(event,0,20)
ash.session_id
mod(ash.p1,16)
ash.p2
ash.p3
o.object_name
o.object_type
CURRENT_FILE#
CURRENT_BLOCK#
ash.SQL_ID
BLOCKING_SESSION

lock_name,
waiter,
lmode,
p2,
p3,
object,
otype,
filen,
blockn,
waiting_sql,
blocker

from
v$active_session_history ash,
all_objects o
where
event like 'enq: %'
and o.object_id (+)= ash.CURRENT_OBJ#
/

http://ashmasters.com

Other Data Sources
In “real time” can also use
–
–
–
–
–
–

v$lock
v$session (v$session_wait)
dba_blockers
dba_waiters
?/rdbms/admin/utllockt.sql
http://www.evdbt.com/enqwaits.sql

Step one: get a lock
Session 1
Session_1> select pk_id from test_tab1
where rownum=1
for update;

PK_ID
---------4051

Step 2: create a blocker
Session 2 Session_2> select pk_id from test_tab1
where pk_id = 4051
for update;

Hangs …

Step 3: release the lock and blocking
Session 1
Session_1> commit;
Commit complete.

Session 2 now continues
PK_ID
---------4051

Locks in OEM:

Application
Wait
click

One SQL

One Session

Click on “Application”

Click on
SQL ID

Click on SQL

SQL waits for lock
get’s lock and does I/O to complete

Click on “Session ID”

Click on
Session ID

No info is lock is gone

Limited Use : lock is already released

Session Before Lock released
Click

Blocker
Holds lock

Waiter

ASH data in EM, but missing blocking info

BLOCKING_SESSION_STATUS
BLOCKING_SESSION
BLOCKING_SESSION_SERIAL#

v$lock & v$session – during lock wait
SQL> select s.sid, s.state, s.event, s.sql_id, l.type, l.lmode
2

from v$session s, v$lock l
s,

3

where s.sid = l.sid

4

and s.username='TESTUSER'

5

order by s.sid;

SID STATE

(+)

EVENT

SQL_ID

TY LMODE

---------- ----------- -------------------------------- ------------- -- ----150 WAITING


0ut22yp7mh229 TM

3

150 WAITING


0ut22yp7mh229 TX

0

157 WAITING

SQL*Net message from client

TX

6

157 WAITING


TM

3

Blocker
Idle, holds locks

Waiter, wants locks

v$lock : after commit by Session 1
SQL> select s.sid, s.state, s.event, s.sql_id, l.type, l.lmode
2

from v$session s, v$lock l

3

where s.sid = l.sid

4

and s.username='TESTUSER'

5

order by s.sid;

SID STATE

(+)

EVENT

SQL_ID

TY LMODE

---------- ----------- -------------------------------- ------------- -- ----150 WAITING


TM

3

150 WAITING


TX

6

157 WAITING


Non-blocking, idle

Holds Locks

v$active_session_history – during and after
SQL> select
a.sample_time,
a.session_id,
a.event,
a.session_state,
a.blocking_session
BSID,
a.blocking_session_status BSTATUS
from v$active_session_history a,
dba_users u
where u.user_id = a.user_id
and u.username = 'TESTUSER';
TIME
-------14.59.37
14.59.36
14.59.35
14.59.34
14.59.33
14.59.32
14.59.31
14.59.30
14.59.29

SID
--150
150
150
150
150
150
150
150
150

STATE
------ON_CPU
ON_CPU
WAITING
WAITING
WAITING
WAITING
WAITING
WAITING
WAITING

a.sql_id,

EVENT
SQL_ID
BSID BSTATUS
----------------------------- ------------- ---- -----------0ut22yp7mh229
NOT IN WAIT
0ut22yp7mh229
NOT IN WAIT
db file scattered read
0ut22yp7mh229
NO HOLDER
db file scattered read
0ut22yp7mh229
NO HOLDER
enq: TX - row lock contention 0ut22yp7mh229 157 VALID

Where is the BLOCKER, 157, info in ASH ?

Time flow
direction

V$active_session_history
SQL> select
a.sample_time,
a.session_id,
a.event,
a.session_state,
a.blocking_session
BSID,
a.blocking_session_status BSTATUS
from v$active_session_history a,
dba_users u
where u.user_id = a.user_id
and u.username = 'TESTUSER';
TIME
22.23.59
22.23.58
22.23.57
22.23.56
22.23.55
22.23.33
22.23.32
22.23.31
22.23.30

SID
147
147
147
147
147
148
148
148
148

STATE
ON CPU
WAITING
WAITING
WAITING
WAITING
WAITING
WAITING
WAITING
WAITING

a.sql_id,

EVENT
enq: TX
enq: TX
enq: TX
enq: TX
db file
db file
db file
db file

- row lock contention
scattered read
scattered read
scattered read
scattered read

SQL> select sql_text from v$sql where sql_id='cda14zb83bb5u’;
sql_id='cda14zb83bb5u’;
SQL_TEXT
-------------------------------------------------------------------------------select count(*) from test_tab1

NOTE:
SESSION_ID
+
SESSION_SERIAL#
Is unique

SQL_ID
BSID BSTATUS
0ut22yp7mh229
NOT IN WAIT
0ut22yp7mh229 148 VALID
cda14zb83bb5u
NO HOLDER
cda14zb83bb5u
NO HOLDER
cda14zb83bb5u
NO HOLDER
cda14zb83bb5u
NO HOLDER

How do we find the SQL that took the
lock?

Session B
update toto set
update toto set
name = ‘ADAMS’
name = ‘ADAMS’
where id = 1;
where id = 1;

TX Lock
Wait for Tx
To commit

Undo
Segment
Header

Undo
Segment

Table Toto
Data Block
Data Block
Header
Header
Transaction 1
Session a
Row 1

update toto set
update toto set
name = ‘SMITH’
name = ‘SMITH’
where id = 1;
where id = toto where id
Delete from 1;
Delete from toto where id
= 2;
= 2;

Logminer : setup
SQL> select group#, thread#, status from v$log;
GROUP#
THREAD# STATUS
---------- ---------- ---------------1
1 CURRENT
2
1 ACTIVE
3
1 ACTIVE
SQL> select group#, member from v$logfile;
GROUP#
---------1
2
3

MEMBER
-----------------------------------------------------------C:ORACLEPRODUCT10.2.0ORADATATEST1020REDO01.LOG
C:ORACLEPRODUCT10.2.0ORADATATEST1020REDO02.LOG

SQL> exec dbms_logmnr.add_logfile('&&my_member');
Enter value for my_member: C:ORACLEPRODUCT10.2.0ORADATATEST1020REDO01.LOG
PL/SQL procedure successfully completed.
SQL> exec dbms_logmnr.start_logmnr(options => dbms_logmnr.dict_from_online_catalog);
PL/SQL procedure successfully completed.

Logminer : setup locking
SQL> create table test_tab1
as select object_id pk_id, object_name from all_objects;
SQL> select rowid, object_name from test_tab1 where pk_id=313;
ROWID
OBJECT_NAME
------------------ -----------------------------AAAN2NAAKAAAaBLAEX SYSTEM_PRIVILEGE_MAP

SESSION_1> update test_tab1 set object_name='SESSION 1' where pk_id=313;
SESSION_2> update test_tab1 set object_name='SESSION 2' where pk_id=313;

Future
Reference:
ROWID

Create
Lock
Wait

Logminer with XID
SQL> select

xid, xidusn, xidslot, xidsqn
from v$transaction order by start_time;

XID
XIDUSN
XIDSLOT
XIDSQN
-------------------- ---------- ---------- ---------0A00240064180000
10
36
6244

Only one transaction active on system, ours
Normal use P2, P3 from wait:

SQL> select username, session# sid, serial# , sql_redo
from v$logmnr_contents
where XID = '0A00240064180000';

'enq: TX - Row Lock Contention'
P2=usn<<16||slot
P3=Sequence
=> XID

USERNAME
SID
SERIAL# SQL_REDO
----------------- ---------- ---------- ----------------UNKNOWN
0
0
set transaction read write;
UNKNOWN
0
0
update "SYS"."TEST_TAB1" set "OBJECT_NAME" =

UNKNOWN

0

0

'SESSION 1' where "OBJECT_NAME" =
'CLUSTER_NODES' and ROWID = 'AAAT5XAABAAAW7hAEr’;
commit;

Finding XID from ASH
WAIT TYPE = 'enq: TX - Row Lock Contention’
Then
P2=usn<<16||slot
P3=Sequence
=> XID
select
distinct
lpad(ltrim(to_char(p2,'XXXXXX')),6,'0')||'00'||
ltrim(to_char(mod(p3,256),'XX'))||
ltrim(to_char(trunc(p3/256),'XX'))||'0000'
block_xid,
to_char(p2,'XXXXXXXX') p2hex,
to_char(p3,'XXXXXXXX') p3hex,
trunc(p2/65536) usn,
mod(p2,65536) slot,
p3 sqn, xid wait_xid
from v$active_session_history
where event like 'enq: T%'
;

'enq: TX - Row Lock Contention'
P2=usn<<16||slot
P3=Sequence
=> XID

Logminer by USN and SLOT
SQL> select

xid, xidusn, xidslot, xidsqn
from v$transaction order by start_time;
XID
XIDUSN
XIDSLOT
XIDSQN
-------------------- ---------- ---------- ---------0A00240064180000
10
36
6244

SYS@TEST1020> select distinct
username, session# sid, serial# , sql_redo
from v$logmnr_contents
where timestamp > sysdate- &minutes/(60*24)
and xidusn=10
and xidslt=36;
Enter value for minutes: 10
USERNAME
SID
SERIAL# SQL_REDO
----------------- ---------- ---------- ----------------UNKNOWN
0
0
set transaction read write;
UNKNOWN
0
0
update "SYS"."TEST_TAB1" set "OBJECT_NAME" =

UNKNOWN

0

'SESSION 1' where "OBJECT_NAME" =
'CLUSTER_NODES' and ROWID = 'AAAT5XAABAAAW7hAEr’;
0 commit;

Dumping Redo Directly
SQL> select rowid, object_name from test_tab1 where pk_id=313;
ROWID
OBJECT_NAME
------------------ -----------------------------AAAN2NAAKAAAaBLAEX SYSTEM_PRIVILEGE_MAP

SYS@TEST1020> select
dbms_rowid.rowid_block_number('&&my_rowid') block_number,
dbms_rowid.rowid_to_absolute_fno('&&my_rowid','SYS','TEST_TAB1') file_id
from dual;
Enter value for my_rowid: AAAN2NAAKAAAaBLAEX
FILE_ID
---------10

BLOCK_NUMBER
-----------106571

Data block row update

FILE_ID

BLOCK_NUMBER

----------

------------

10

106571

SYS@TEST1020> alter system dump logfile '&&my_member'
dba min 10 106571 dba max 10 106571;
System altered
DUMP OF REDO FROM FILE 'C:ORACLEPRODUCT10.2.0ORADATATEST1020REDO01.LOG' Opcodes
*.* DBAs: (file # 10, block # 106571) thru (file # 10, block # 106571) RBAs:
0x000000.00000000.0000 thru 0xffffffff.ffffffff.ffff SCNs: scn: 0x0000.00000000 thru
scn: 0xffff.ffffffff
…
REDO RECORD - Thread:1 RBA: 0x0000b3.00000009.0010 LEN: 0x0210 VLD: 0x0d SCN:
0x0000.008a42e6 SUBSCN: 1 04/20/2009 20:46:57 CHANGE #1 TYP:2 CLS: 1 AFN:10
DBA:0x0281a04b OBJ:56717 SCN:0x0000.008a4239 SEQ: 2 OP:11.19 KTB Redo op:
0x11 ver: 0x01
op: F xid: 0x000a.024.00001864
uba: 0x0080009d.031a.27
0A00240064180000

CLS: 1 - Data Class Block
OP:11.19 - Operation Update Multiple Rows.

Verify DBA and Table
REDO RECORD - Thread:1 RBA: 0x0000b3.00000009.0010 LEN: 0x0210 VLD: 0x0d SCN:
0x0000.008a42e6 SUBSCN: 1 04/20/2009 20:46:57 CHANGE #1 TYP:2 CLS: 1 AFN:10
DBA:0x0281a04b OBJ:56717 SCN:0x0000.008a4239 SEQ: 2 OP:11.19 KTB Redo op:
0x11 ver: 0x01
op: F xid: 0x000a.024.00001864
uba: 0x0080009d.031a.27

TESTUSER@TEST1020> select object_name, object_type
from user_objects
where object_id=56717;
OBJECT_NAME
OBJECT_TYPE
------------------- ------------------TEST_TAB1
TABLE
SYS@TEST1020> select to_char(dbms_utility.make_data_block_address(10,106571),
'XXXXXXXX') DBA from dual;
DBA
--------281A04B

Update Value
“session 1”
Array Update of 1 rows:
…
col 1: [ 9] 53 45 53 53 49 4f 4e 20 30
CHANGE #3 TYP:2 CLS:1 AFN:1 DBA:0x00416ee1 OBJ:81495
SCN:0x0000.01052c55 SEQ:1 OP:11.19 ENC:0 RBL:0
…
col 1: [ 9] 53 45 53 53 49 4f 4e 20 32

“session 2”

Last Try: flashback
SELECT

VERSIONS_XID
,
VERSIONS_STARTTIME
,
VERSIONS_ENDTIME
,
VERSIONS_STARTSCN
,
VERSIONS_ENDSCN
,
VERSIONS_OPERATION
,
object_name
FROM
SYS.TEST_TAB1
VERSIONS BETWEEN
TIMESTAMP MINVALUE AND MAXVALUE
where VERSIONS_XID is not null
ORDER BY VERSIONS_STARTTIME

/

From ASH
BLOCK_XID
---------------0A00010072640000

P2HEX
P3HEX
USN
SLOT
SQN WAIT_XID
--------- --------- ---------- ---------- ---------- ---------------A0001
6472
10
1
25714

From Flashback
VERSIONS_XID
VERSIONS_STARTTIME
ENDTIME STARTSCN ENDSCN V OBJECT_NAME
---------------- --------------------- ------- -------- ------- - -------------0A00010072640000 15-OCT-13 06.46.30 PM
17042888
U SESSION 1

P1 = name | mode
select distinct parameter1 from v$event_name
where name like 'enq:%'

PARAMETER1
name|mode
select
event,
mod(p1,16) as "mode"
from v$active_session_history
where event like 'enq:%‘;
EVENT

mode
6
4

• Mode 6 (exclusive)

– modification of a row lock

• Mode 4 (share)
– ??


if P1 = 1415053318
then mode = 6
Then it is a data block
row lock

Copyright 2006

TX – Mode 4

if P1 = 1415053316
then mode = 4
Not same data but conflicts
Copyright 2006

Mode 4, happens for 3 reasons
1. Unique key contention
2. Foreign Key contention
3. Bitmap index contention
(others?)

1. enq: TX - row lock contention
Mode 4 , unique index

User 2

User 1
create table p(n number);
create unique index p_i on p(n);
insert into p values(2);

insert into p values(2);
PK

Table

ID
2?

ID Value
2?

Mode 4, foreign key
User 1
create table parent (
id number primary key);
create table child (
id number references parent,
name varchar2(20));
insert into parent values (2);
PK
ID
2?

Parent
ID Value
2?

User 2

insert into child values (2,88);
Child
ID Name
2

Mode 4, bitmap
• Bitmaps are compressed
• Changes to the same bitmap cause locks

Value Start
Rowid
1
000.000.0000

End
Bitmap
Rowid
01010000111000011100001100
000.000.000

2

01010000111000011100001100
000.000.0000

000.000.000

Session 1
create table t1 ((
Different rows but
create table t1
n1
number(4),
n1
number(4),
same key value
row number(4));
row number(4));
insert into t1
insert into t1
select 1, rownum
select 1, rownum
from all_objects
from all_objects
where rownum <= 400;
where rownum <= 400;
commit;
commit;
create bitmap index i1 on t1(n1);
create bitmap index i1 on t1(n1);
update t1 set n1 = 2
Session 2
where row= 12;
where row= 12;
where row= 13;
where row= 13;

•
•

Bitmaps are compressed
Changes to the same bitmap chunk cause locks

Value Start End
Bitmap
Rowid Rowid
1
01010000111000011100001100
200.0

1
2

205.0
200.0

block

204.7
210.3
205.6

row

01010000111000011100001100
01010000111000011100001100

Value Start End
Bitmap
Rowid Rowid
1
01010000111000011100001100
200.0

2
3

205.0
200.0

204.7
210.3
205.6

01010000111000011100001100
01010000111000011100001100

Session 1
Update id=12
set value 2

Session 2
Update id=13
set value 2

Summary: TX 4 from ASH
Mode 4, unique key
SID LM
P2
P3 OBJ

uniq index
ST
EVENT
----- ---------------------10:39 enq: TX - row lock c
10:39 enq: TX - row lock c

--- --- ------ ---141
4 655406 6672
141
4 655406 6672
141
4 655406 6672
141
4 655406 6672

OTYPE FN BLOCKN SQL_ID
----- ----- --- ------ --1
0
0 bjvx94vnxtxgv
-1
0
0 bjvx94vnxtxgv
-1
0
0 bjvx94vnxtxgv
-1
0
0 bjvx94vnxtxgv

BSID
158
158
158
158


FK (10.2.0.3)
ST
EVENT
----- ---------------------10:41 enq: TX - row lock c

SID LM
P2
P3 OBJ
--- --- ------ ---- ----144
4 179681 7074 CHILD
144
4 179681 7074 CHILD
144
4 179681 7074 CHILD

----- --- ------ -TABLE
1 60954 ahm7c9rupbz9r
TABLE
TABLE

BSID

----- --- ------ -INDEX
0
0 azav296xxqcjx
INDEX
0
0 azav296xxqcjx
INDEX
0
0 azav296xxqcjx
INDEX
0
0 azav296xxqcjx

BSID

1
1
1

Mode 4, bitmap

bitmap
ST
EVENT
----- ---------------------10:41 enq: TX - row lock c

SID LM
P2
P3 OBJ
--- --- ------ ---- ----143
4 966081 4598 I1
143
4 966081 4598 I1
143
4 966081 4598 I1
143
4 966081 4598 I1

Copyright 2006 Kyle Hailey

144
144
144
144

Specific ‘enq: TX’ wait events
•

– ITL space waits

•

enq: TX - index contention
– Index block split

•

Unusual enq: TX – contention
– Alter tablespace … read only;
– Free Lists slot waits
– Possible with two phase commit


Data Block
Data Block
Header
Header
ITL

Data

Copyright 2006

Transaction 1 Info
Transaction 2 Info


Data Block
Data Block
Header
Header
Transaction 1
Transaction 2
Row 3
Row 2
Data
Row 1

Copyright 2006

Transaction 3

create table itl (
create table itl (
id number,
id number,
data varchar2(20)
data varchar2(20)
)
)
pctfree 0
pctfree 0
initrans 1
initrans 1
;
;
insert into itl select rownum,'a' from all_objects
insert into itl select rownum,'a' from all_objects
where rownum < 2000;
where rownum < 2000;
commit;
commit;
session 1: update itl set data=data where id=1;

enq: TX - contention
1. Altering tablespace read only with open transaction
Example
– Session 1 – start transaction, don’t commit
– Session 2 – alter tablespace read only

1. Data File Extension – waiter waiting for another session to extend
file

enq: TM - contention
•
•

TX locks have a corresponding TM lock
TM locks the structure from change

 Parameter1

= object id

LOCK
Parmeter1
LOCK
Parmeter1
------- --------------- --------enq: TM name|mode
enq: TM name|mode

Parmeter2(ID1) Parameter3(ID2)
Parmeter2(ID1) Parameter3(ID2)
----------------------------------------------------object #
table/partition
object #
table/partition

Exclusive Row Level Lock
User 1
create table parent (
id number primary key);
create table child (
id number references parent,
name varchar2(20));
commit;
delete from parent where id=2;

User 2

insert into child values (1,2);
No commit

PK

Parent

Child

ID
1
X
2

ID
1
X
2

ID Name
1

Session 1
Session 2

Value

Insert into Child ID=1
Delete from Parent where ID=2 :

Enqueue TM 4
Session 2 doesn’t know the value Session 1 inserted
Session 2 only knows there is an outstanding change

enq: TM – contention Solution
PK

Parent

ID
1
2

ID

Value

Index
ID
1

Child
ID Name

Foreign Key
Session 1: Insert into Child ID=1
Session 2: Delete from Parent ID=2
OK – can verify quickly in the child index

Without TM Locks
Child
Name
ID
1
2
3
4
…
10000

Delete
Parent

Child
Delete
Child

Could scan Child table for value “2” and
someone could come in behind and delete
value 2 in an area that is already scanned
but before the scan has finished. The TM
lock prevents this

Name
ID
1
2
3
4
…
10000

Delete
Parent

TM Further Investigation
select
event,
sql_id,
mod(p1,16) as "mode",
p2|| ' ' || o.name obj
from v$active_session_history ash,
obj$ o
where
event like 'enq: TM%'
and o.obj# (+)= ash.p2
order by sample_time;
EVENT
enq:
enq:
enq:
enq:
enq:
enq:

TM
TM
TM
TM
TM
TM

SQL_ID
-

contention
contention
contention
contention
contention
contention

8zw36yw3fq4yy
8zw36yw3fq4yy
8zw36yw3fq4yy
8zw36yw3fq4yy
8zw36yw3fq4yy
8zw36yw3fq4yy

mode OBJ
4
4
4
4
4
4

53372
53372
53372
53372
53372
53372

CHILD
CHILD
CHILD
CHILD
CHILD
CHILD

Other Resources

@?/rdbms/admin/utllockt
WAITING_SESSION LOCK_TYPE

MODE_REQUESTED MODE_HELD LOCK_ID1

LOCK_ID2

--------------- ----------- -------------- --------- --------- -------144
139

None
Transaction Share

Exclusive 131113

7507

OOUG: Oracle transaction locking

OOUG: Oracle transaction locking

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Editor's Notes