使用dbms_transaction来获得事务ID

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。