一般找出当前事务ID与回滚段最常见的方法就是执行以下SQL
SQL> select xidusn, xidslot, xidsqn from v$transaction, v$session where saddr=ses_addr;
XIDUSN XIDSLOT XIDSQN
---------- ---------- ----------
6 27 9338
而最简单与最容易的方法是使用dbms_transaction PL/SQL包。下面使用一个例子来进行说明如何使用dbms_transaction PL/SQL包来找出当前事务ID，并使用undo header dump信息来进行验证。
SQL> select dbms_transaction.local_transaction_id from dual; LOCAL_TRANSACTION_ID -------------------------------------------------------------------------------- SQL> set transaction read write; Transaction set. SQL> select dbms_transaction.local_transaction_id from dual; LOCAL_TRANSACTION_ID -------------------------------------------------------------------------------- 6.27.9339
6 –> undo segment number(USN) undo段号
27 –> Transaction slot in the transaction list 事务列表中的事务插槽
9339 –> Sequence number(the number of times the given slot has been used) 序列号(给定的事务插槽被使用的次数)
上面的事务ID可以通过undo segment的undo header dump信息来进行验证
1.找到回滚段名
SQL> select * from v$rollname where USN=6;
USN NAME
---------- ------------------------------
6 _SYSSMU6_3214712007$
2.转储回滚段header
SQL> alter system dump undo header '_SYSSMU6_3214712007$'; System altered. SQL> select 2 d.value||'/'||lower(rtrim(i.instance, 3 chr(0)))||'_ora_'||p.spid||'.trc' trace_file_name 4 from ( select p.spid 5 from v$mystat m, 6 v$session s,v$process p 7 where m.statistic# = 1 and s.sid = m.sid and p.addr = s.paddr) p, 8 ( select t.instance from v$thread t,v$parameter v 9 where v.name = 'thread' and 10 (v.value = 0 or t.thread# = to_number(v.value))) i, 11 ( select value from v$parameter 12 where name = 'user_dump_dest') d; TRACE_FILE_NAME -------------------------------------------------------------------------------- /u01/app/oracle/diag/rdbms/jyrac/jyrac1/trace/jyrac1_ora_16785.trc
跟踪文件信息如下:
Unix process pid: 16785, image: oracle@jyrac1 (TNS V1-V3)
*** 2016-04-28 09:10:02.380
*** SESSION ID:(147.9205) 2016-04-28 09:10:02.380
*** CLIENT ID:() 2016-04-28 09:10:02.380
*** SERVICE NAME:(SYS$USERS) 2016-04-28 09:10:02.380
*** MODULE NAME:(sqlplus@jyrac1 (TNS V1-V3)) 2016-04-28 09:10:02.380
*** ACTION NAME:() 2016-04-28 09:10:02.380
********************************************************************************
Undo Segment: _SYSSMU6_3214712007$ (6)
********************************************************************************
Extent Control Header
-----------------------------------------------------------------
Extent Header:: spare1: 0 spare2: 0 #extents: 3 #blocks: 143
last map 0x00000000 #maps: 0 offset: 4080
Highwater:: 0x00c00aaa ext#: 2 blk#: 42 ext size: 128
#blocks in seg. hdr's freelists: 0
#blocks below: 0
mapblk 0x00000000 offset: 2
Unlocked
Map Header:: next 0x00000000 #extents: 3 obj#: 0 flag: 0x40000000
Extent Map
-----------------------------------------------------------------
0x00c000d1 length: 7
0x00c00108 length: 8
0x00c00a80 length: 128
Retention Table
-----------------------------------------------------------
Extent Number:0 Commit Time: 1461797986
Extent Number:1 Commit Time: 1461800269
Extent Number:2 Commit Time: 1461796031
TRN CTL:: seq: 0x0c6a chd: 0x001e ctl: 0x001f inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x00c00aa6.0c6a.18 scn: 0x0000.014ce06a
Version: 0x01
FREE BLOCK POOL::
uba: 0x00000000.0c6a.17 ext: 0x2 spc: 0x128c
uba: 0x00000000.0c6a.02 ext: 0x2 spc: 0x1ace
uba: 0x00000000.0c6a.14 ext: 0x2 spc: 0x13fe
uba: 0x00000000.0bc3.01 ext: 0x2 spc: 0x1f84
uba: 0x00000000.0000.00 ext: 0x0 spc: 0x0
TRN TBL::
index state cflags wrap# uel scn dba parent-xid nub stmt_num cmt
------------------------------------------------------------------------------------------------
0x00 9 0x00 0x2471 0x001a 0x0000.014ce250 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804655
0x01 9 0x00 0x2479 0x0008 0x0000.014ce7f8 0x00c00aa9 0x0000.000.00000000 0x00000001 0x00000000 1461805256
0x02 9 0x00 0x2476 0x000c 0x0000.014ce44e 0x00c00aa6 0x0000.000.00000000 0x00000001 0x00000000 1461805136
0x03 9 0x00 0x2472 0x000b 0x0000.014ce2d5 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804775
0x04 9 0x00 0x2477 0x0000 0x0000.014ce210 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804595
0x05 9 0x00 0x2478 0x0017 0x0000.014ce3d0 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461805015
0x06 9 0x00 0x2478 0x0018 0x0000.014ce4db 0x00c00aa6 0x0000.000.00000000 0x00000001 0x00000000 1461805245
0x07 9 0x00 0x2479 0x000e 0x0000.014ce353 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804894
0x08 9 0x00 0x2476 0x0016 0x0000.014ce815 0x00c00aa9 0x0000.000.00000000 0x00000001 0x00000000 1461805256
0x09 9 0x00 0x247e 0x0012 0x0000.014ce74b 0x00c00aa9 0x0000.000.00000000 0x00000001 0x00000000 1461805247
0x0a 9 0x00 0x2477 0x001d 0x0000.014ce10d 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804355
0x0b 9 0x00 0x247a 0x0007 0x0000.014ce326 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804835
0x0c 9 0x00 0x2471 0x000f 0x0000.014ce4d9 0x00c00aa9 0x0000.000.00000000 0x00000001 0x00000000 1461805245
0x0d 9 0x00 0x2473 0x001c 0x0000.014ce284 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804715
0x0e 9 0x00 0x2478 0x0011 0x0000.014ce358 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804894
0x0f 9 0x00 0x2470 0x0006 0x0000.014ce4da 0x00c00aaa 0x0000.000.00000000 0x00000003 0x00000000 1461805245
0x10 9 0x00 0x2477 0x0001 0x0000.014ce7e8 0x00c00aa9 0x0000.000.00000000 0x00000001 0x00000000 1461805256
0x11 9 0x00 0x2472 0x0005 0x0000.014ce38a 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804954
0x12 9 0x00 0x2478 0x0010 0x0000.014ce7d8 0x00c00aa9 0x0000.000.00000000 0x00000001 0x00000000 1461805256
0x13 9 0x00 0x2473 0x0003 0x0000.014ce2c0 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804775
0x14 9 0x00 0x247a 0x0004 0x0000.014ce1a2 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804474
0x15 9 0x00 0x2476 0x000a 0x0000.014ce106 0x00000000 0x0000.000.00000000 0x00000000 0x00000000 1461804355
0x16 9 0x00 0x246d 0x001f 0x0000.014ce867 0x00000000 0x0000.000.00000000 0x00000000 0x00000000 1461805315
0x17 9 0x00 0x2473 0x0019 0x0000.014ce3f4 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461805040
0x18 9 0x00 0x247a 0x0009 0x0000.014ce5a4 0x00c00aa9 0x0000.000.00000000 0x00000001 0x00000000 1461805245
0x19 9 0x00 0x2475 0x0002 0x0000.014ce441 0x00c00aa6 0x0000.000.00000000 0x00000002 0x00000000 1461805135
0x1a 9 0x00 0x2478 0x000d 0x0000.014ce254 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804655
0x1b 10 0x80 0x247b 0x0002 0x0000.014ce8fc 0x00000000 0x0000.000.00000000 0x00000000 0x00000000 0
0x1c 9 0x00 0x2477 0x0013 0x0000.014ce2b7 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804775
0x1d 9 0x00 0x2474 0x0014 0x0000.014ce155 0x00c00aa5 0x0000.000.00000000 0x00000001 0x00000000 1461804415
0x1e 9 0x00 0x246d 0x0021 0x0000.014ce079 0x00c00aa3 0x0000.000.00000000 0x00000001 0x00000000 1461804174
0x1f 9 0x00 0x2477 0xffff 0x0000.014ce8de 0x00c00aa6 0x0000.000.00000000 0x00000001 0x00000000 1461805376
0x20 9 0x00 0x2478 0x0015 0x0000.014ce0dc 0x00000000 0x0000.000.00000000 0x00000000 0x00000000 1461804295
0x21 9 0x00 0x2479 0x0020 0x0000.014ce0a7 0x00c00aa3 0x0000.000.00000000 0x00000001 0x00000000 1461804235
EXT TRN CTL::
usn: 6
sp1:0x00000000 sp2:0x00000000 sp3:0x00000000 sp4:0x00000000
sp5:0x00000000 sp6:0x00000000 sp7:0x00000000 sp8:0x00000000
EXT TRN TBL::
index extflag extHash extSpare1 extSpare2
---------------------------------------------------
0x00 0x00000000 0x00000000 0x00000000 0x00000000
0x01 0x00000000 0x00000000 0x00000000 0x00000000
0x02 0x00000000 0x00000000 0x00000000 0x00000000
0x03 0x00000000 0x00000000 0x00000000 0x00000000
0x04 0x00000000 0x00000000 0x00000000 0x00000000
0x05 0x00000000 0x00000000 0x00000000 0x00000000
0x06 0x00000000 0x00000000 0x00000000 0x00000000
0x07 0x00000000 0x00000000 0x00000000 0x00000000
0x08 0x00000000 0x00000000 0x00000000 0x00000000
0x09 0x00000000 0x00000000 0x00000000 0x00000000
0x0a 0x00000000 0x00000000 0x00000000 0x00000000
0x0b 0x00000000 0x00000000 0x00000000 0x00000000
0x0c 0x00000000 0x00000000 0x00000000 0x00000000
0x0d 0x00000000 0x00000000 0x00000000 0x00000000
0x0e 0x00000000 0x00000000 0x00000000 0x00000000
0x0f 0x00000000 0x00000000 0x00000000 0x00000000
0x10 0x00000000 0x00000000 0x00000000 0x00000000
0x11 0x00000000 0x00000000 0x00000000 0x00000000
0x12 0x00000000 0x00000000 0x00000000 0x00000000
0x13 0x00000000 0x00000000 0x00000000 0x00000000
0x14 0x00000000 0x00000000 0x00000000 0x00000000
0x15 0x00000000 0x00000000 0x00000000 0x00000000
0x16 0x00000000 0x00000000 0x00000000 0x00000000
0x17 0x00000000 0x00000000 0x00000000 0x00000000
0x18 0x00000000 0x00000000 0x00000000 0x00000000
0x19 0x00000000 0x00000000 0x00000000 0x00000000
0x1a 0x00000000 0x00000000 0x00000000 0x00000000
0x1b 0x00000000 0x00000000 0x00000000 0x00000000
0x1c 0x00000000 0x00000000 0x00000000 0x00000000
0x1d 0x00000000 0x00000000 0x00000000 0x00000000
0x1e 0x00000000 0x00000000 0x00000000 0x00000000
0x1f 0x00000000 0x00000000 0x00000000 0x00000000
0x20 0x00000000 0x00000000 0x00000000 0x00000000
0x21 0x00000000 0x00000000 0x00000000 0x00000000
从Undo Segment: _SYSSMU6_3214712007$ (6)可以知道回滚段号是6,找到 state为10的记录
index state cflags wrap# uel scn dba parent-xid nub stmt_num cmt ------------------------------------------------------------------------------------------------ 0x1b 10 0x80 0x247b 0x0002 0x0000.014ce8fc 0x00000000 0x0000.000.00000000 0x00000000 0x00000000 0
其中0x1b=27
SQL> select to_number('1b','xxx') from dual;
TO_NUMBER('1B','XXX')
---------------------
27
0x247b=9339
SQL> select to_number('247b','xxxx') from dual;
TO_NUMBER('247B','XXXX')
------------------------
9339
从上面的信息可以看到与我们使用dbms_transaction PL/SQL包所获得的事务ID信息一致。