Transaction Internal

原文地址：Transaction<wbr>Internal</wbr> 作者：Tech苦行

本博文介绍一个transaction在相应的undo segment上完成交易以及undo segment状态的变化。
插入一条记录到my_table:
SQL> insert into my_table select * from dba_tables where owner='NAI2276';

已创建 1 行。

查到此transaction相对应的undo segment:
11:41:58 SQL> select xidusn from v$transaction t, v$session s
11:45:45<wbr><wbr> 2<wbr> where t.ADDR=s.TADDR --taddr: transaction addr<br> 11:45:45<wbr><wbr> 3<wbr> and<wbr><wbr> s.sid=138<br> 11:45:45<wbr><wbr> 4<wbr> and<wbr><wbr> s.SERIAL#=57;<br><br><wbr><wbr><wbr> XIDUSN<br> ----------<br><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> 9<br><br> 已用时间:<wbr> 00: 00: 00.00<br><br> 查到编号为9的undo segment的名字:<br><img alt="" title="[转载]Transaction&lt;wbr&gt;Internal">11:41:17 SQL&gt; select segment_name from dba_rollback_segs where segment_id=9;<br><br> SEGMENT_NAME<br> ------------------------------------------------------------<br> _SYSSMU9_2269999616$<br><br> 已用时间:<wbr> 00: 00: 00.01<br><br> 对此undo segment做dump:<br><img alt="" title="[转载]Transaction&lt;wbr&gt;Internal">11:26:37 SQL&gt; alter system dump undo header '_SYSSMU9_2269999616$'<br><br> 系统已更改。<br><br> 已用时间:<wbr> 00: 00: 00.00<br><br><br><wbr><br> ********************************************************************************<br> Undo Segment:<wbr> _SYSSMU9_2269999616$ (9)<br> ********************************************************************************<br><wbr> Extent Control Header<br><wbr> -----------------------------------------------------------------<br><wbr> Extent Header:: spare1: 0<wbr><wbr><wbr><wbr><wbr> spare2: 0<wbr><wbr><wbr><wbr><wbr> #extents: 40<wbr><wbr><wbr><wbr> #blocks: 3559<wbr><br><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> last map<wbr> 0x00000000<wbr> #maps: 0<wbr><wbr><wbr><wbr><wbr> offset: 4080<wbr><br><wbr><wbr><wbr><wbr><wbr> Highwater::<wbr> 0x00c0176f<wbr> ext#: 17<wbr><wbr><wbr><wbr> blk#: 111<wbr><wbr><wbr> ext size: 128<wbr><wbr><br><wbr> #blocks in seg. hdr's freelists: 0<wbr><wbr><wbr><wbr><br><wbr> #blocks below: 0<wbr><wbr><wbr><wbr><br><wbr> mapblk<wbr> 0x00000000<wbr> offset: 17<wbr><wbr><wbr><br><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> Unlocked<br><wbr><wbr><wbr><wbr> Map Header:: next<wbr> 0x00000000<wbr> #extents: 40<wbr><wbr> obj#: 0<wbr><wbr><wbr><wbr><wbr> flag: 0x40000000<br><br><wbr> TRN TBL::<br><wbr><br><wbr> index<wbr> state cflags<wbr> wrap#<wbr><wbr><wbr> uel<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> scn<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> dba<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> parent-xid<wbr><wbr><wbr> nub<wbr><wbr><wbr><wbr> stmt_num<wbr><wbr><wbr> cmt<br><wbr> ------------------------------------------------------------------------------------------------<br><wbr><wbr> 0x00<wbr><wbr><wbr> 9<wbr><wbr><wbr> 0x00<wbr> 0x01cb<wbr> 0x0021<wbr> 0x0000.00080bac<wbr> 0x00c0176e<wbr> 0x0000.000.00000000<wbr> 0x00000001<wbr><wbr> 0x00000000<wbr> 1321499430<br><wbr><wbr> 0x01<wbr><wbr><wbr> 9<wbr><wbr><wbr> 0x00<wbr> 0x01cb<wbr> 0x0008<wbr> 0x0000.00080055<wbr> 0x00c0176b<wbr> 0x0000.000.00000000<wbr> 0x00000001<wbr><wbr> 0x00000000<wbr> 1321492859<br><wbr><wbr> 0x02<wbr><wbr><wbr> 9<wbr><wbr><wbr> 0x00<wbr> 0x01cc<wbr> 0x001b<wbr> 0x0000.00080be0<wbr> 0x00c0176e<wbr> 0x0000.000.00000000<wbr> 0x00000001<wbr><wbr> 0x00000000<wbr> 1321499430<br><wbr><wbr> 0x03<wbr><wbr><wbr> 9<wbr><wbr><wbr> 0x00<wbr> 0x01cd<wbr> 0x000c<wbr> 0x0000.00080ab8<wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>