今天是2014-03-12，在进行数据库性能调优过程中，突然翻到了之前一封邮件，信息如下：
从日志中看，发现存在行级排他锁存在争用以致产生了死锁。
问题描述：
*** 2013-12-02 17:03:10.148
DEADLOCK DETECTED ( ORA-00060 )
[Transaction Deadlock]
The following deadlock is not an ORACLE error. It is a
deadlock due to user error in the design of an application
or from issuing incorrect ad-hoc SQL. The following
information may aid in determining the deadlock:
Deadlock graph:
---------Blocker(s)-------- ---------Waiter(s)---------
Resource Name process session holds waits process session holds waits
TX-000b002b-002be2d3 61 958 X 141 876 X
TX-0009001c-000d5ffa 141 876 X 61 958 X
session 958: DID 0001-003D-00001BC1 session 876: DID 0001-008D-0000B424
session 876: DID 0001-008D-0000B424 session 958: DID 0001-003D-00001BC1
Rows waited on:
Session 876: obj - rowid = 0000DE75 - AAAN51AArAAAA6mAAO
(dictionary objn - 56949, file - 43, block - 3750, slot - 14)
Session 958: obj - rowid = 00014F07 - AAAU8HABXAAA7BqAAI
(dictionary objn - 85767, file - 87, block - 241770, slot - 8)
Information on the OTHER waiting sessions:
Session 876:
sid: 876 ser: 38057 audsid: 7879846 user: 47/EPMFRAMEWORK
flags: (0x41) USR/- flags_idl: (0x1) BSY/-/-/-/-/-
flags2: (0x8)
pid: 141 O/S info: user: orarep, term: UNKNOWN, ospid: 11195
image: oracle@pmsdb2
O/S info: user: webpms2, term: unknown, ospid: 1234, machine: pmsrep1
program: JDBC Thin Client
application name: JDBC Thin Client, hash value=2546894660
Current SQL Statement:
UPDATE AP_COLL_INFO_T T SET T.PROCINST_ID = NULL, T.IF_PROJECT_INHERITED = ‘0‘ WHERE T.INVEST_SNO = :1
End of information on OTHER waiting sessions.
Current SQL statement for this session:
UPDATE AP_PROJECT_INFO_EDITION_T T SET T.IF_INHERITED=‘1‘ WHERE T.AP_PRJ_SNO=:1
在上面可以获得很多可以帮助诊断问题的信息，该信息显示由于应用逻辑错误，导致了死锁的产生。
另外还可以通过相关sql获得一些简要信息：
eg：
2、分解rowid获得产生死锁等待的对象信息如下： SQL> select a.owner, 2 a.object_name, 3 a.object_type, 4 a.last_ddl_time, 5 a.created, 6 a.status, 7 b.object, 8 b.fno, 9 b.rownu, 10 b.block 11 from (select dbms_rowid.rowid_object(‘AAAU8HABXAAA7BqAAI‘) object, 12 dbms_rowid.rowid_relative_fno(‘AAAU8HABXAAA7BqAAI‘) fno, 13 dbms_rowid.rowid_row_number(‘AAAU8HABXAAA7BqAAI‘) rowNU, 14 dbms_rowid.rowid_block_number(‘AAAU8HABXAAA7BqAAI‘) block 15 from dual) b, 16 dba_objects a 17 where a.object_id = b.object; OWNER OBJECT_NAME OBJECT_TYPE LAST_DDL_TIME CREATED STATUS OBJECT FNO ROWNU BLOCK ------------------------------ -------------------------------------------------------------------------------- ------------------- ------------- ----------- ------- ---------- ---------- ---------- ---------- EPMFRAMEWORK AP_PROJECT_INFO_EDITION_T TABLE 2013-11-27 11 2012-06-05 VALID 85767 87 8 241770 SQL> SQL> select a.owner, 2 a.object_name, 3 a.object_type, 4 a.last_ddl_time, 5 a.created, 6 a.status, 7 b.object, 8 b.fno, 9 b.rownu, 10 b.block 11 from (select dbms_rowid.rowid_object(‘AAAN51AArAAAA6mAAO‘) object, 12 dbms_rowid.rowid_relative_fno(‘AAAN51AArAAAA6mAAO‘) fno, 13 dbms_rowid.rowid_row_number(‘AAAN51AArAAAA6mAAO‘) rowNU, 14 dbms_rowid.rowid_block_number(‘AAAN51AArAAAA6mAAO‘) block 15 from dual) b, 16 dba_objects a 17 where a.object_id = b.object; OWNER OBJECT_NAME OBJECT_TYPE LAST_DDL_TIME CREATED STATUS OBJECT FNO ROWNU BLOCK ------------------------------ -------------------------------------------------------------------------------- ------------------- ------------- ----------- ------- ---------- ---------- ---------- ---------- EPMFRAMEWORK AP_COLL_INFO_T TABLE 2012-04-01 21 2011-10-05 VALID 56949 43 14 3750 SQL> 3、导致此问题的sql语句为： SQL> SELECT B.SQL_ID,SQL_FULLTEXT,B.EVENT,B.SAMPLE_TIME,B.SESSION_ID FROM V$sqL A INNER JOIN ( 2 select session_id, session_serial#, sql_id, event, SAMPLE_TIME 3 from dba_hist_active_sess_history 4 where event = ‘enq: TX - row lock contention‘ 5 and sample_time > 6 to_date(‘2013-12-02 17:02:00‘, ‘YYYY-MM-DD HH24:MI:SS‘) ) B 7 ON A.SQL_ID=B.SQL_ID; SQL_ID SQL_FULLTEXT EVENT SAMPLE_TIME SESSION_ID ------------- -------------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------- -------------------------------------------------------------------------------- ---------- 9bwcgrn96cx62 INSERT INTO rt_actinst_data(instance_id,name,type,data,merge_type,rdata_app)VALUES(:1,:2,:3,:4,:5,:6) enq: TX - row lock contention 02-12月-13 05.03.21.158 下午 959 9bwcgrn96cx62 INSERT INTO rt_actinst_data(instance_id,name,type,data,merge_type,rdata_app)VALUES(:1,:2,:3,:4,:5,:6) enq: TX - row lock contention 02-12月-13 05.03.11.158 下午 959 1npq5jnavnc0k UPDATE AP_PROJECT_INFO_EDITION_T T SET T.IF_INHERITED=‘1‘ WHERE T.AP_PRJ_SNO=:1 enq: TX - row lock contention 02-12月-13 05.03.01.153 下午 958 9bwcgrn96cx62 INSERT INTO rt_actinst_data(instance_id,name,type,data,merge_type,rdata_app)VALUES(:1,:2,:3,:4,:5,:6) enq: TX - row lock contention 02-12月-13 05.03.01.153 下午 959 1npq5jnavnc0k UPDATE AP_PROJECT_INFO_EDITION_T T SET T.IF_INHERITED=‘1‘ WHERE T.AP_PRJ_SNO=:1 enq: TX - row lock contention 02-12月-13 05.02.51.148 下午 958 1npq5jnavnc0k UPDATE AP_PROJECT_INFO_EDITION_T T SET T.IF_INHERITED=‘1‘ WHERE T.AP_PRJ_SNO=:1 enq: TX - row lock contention 02-12月-13 05.02.41.148 下午 958 1npq5jnavnc0k UPDATE AP_PROJECT_INFO_EDITION_T T SET T.IF_INHERITED=‘1‘ WHERE T.AP_PRJ_SNO=:1 enq: TX - row lock contention 02-12月-13 05.02.31.148 下午 958 7 rows selected SQL>
我要说的是在trace中可以获得一个deadlock graph:
看个例子：
那么本次锁的最后组合为：tx x x；
最后总结一下（一见明了）：
参考（1507093.1）