;
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAE? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? insert into "SYS"."TEST"("EMPNO","SAL") values ('7654','1250');
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAD? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? insert into "SYS"."TEST"("EMPNO","SAL") values ('7566','2975');
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAC? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? insert into "SYS"."TEST"("EMPNO","SAL") values ('7521','1250');
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAB? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? insert into "SYS"."TEST"("EMPNO","SAL") values ('7499','1600');
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAA? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? insert into "SYS"."TEST"("EMPNO","SAL") values ('7369','800');
07000500D6050000? ? 1940035? ? 1940037 AAAV4EAABAAARfpAAA? UPDATE? ? ? ? ? ? ? ? ? ? ? ? ? update "SYS"."TEST" set "SAL" = '100' where ROWID = 'AAAV4EAABAAARfpAAA';
0900130035060000? ? 1939850? ? 1939857 AAAV4EAABAAARfpAAA? UPDATE? ? ? ? ? ? ? ? ? ? ? ? ? update "SYS"."TEST" set "SAL" = '800' where ROWID = 'AAAV4EAABAAARfpAAA';
16 rows selected
3、xid检索
最后我们聊聊查询flashback_transaction_query视图使用XID事务唯一标记特点。视图中xid类型是一个RAW类型，表现出来通常是一个字符串。
在实际中，我们常常发现使用字符串标记进行检索的时候速度比较慢。
SQL> select xid, start_scn, commit_scn, row_id, operation,undo_sql from flashback_transaction_query where xid='060016002F060000';
XID? ? ? ? ? ? ? START_SCN COMMIT_SCN ROW_ID? ? ? ? ? ? ? OPERATION? ? ? ? ? ? ? ? ? ? ? ? UNDO_SQL
---------------- ---------- ---------- ------------------- -------------------------------- --------------------------------------------------------------------------------
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAN? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? insert into "SYS"."TEST"("EMPNO","SAL") values ('7934','1300');
（篇幅原因，有省略……）
15 rows selected
Executed in 10.686 seconds
在官方推荐的查询方式中，建议使用hextoraw函数对字符串进行处理一下。
SQL> select xid, start_scn, commit_scn, row_id, operation,undo_sql from flashback_transaction_query where xid=hextoraw('060016002F060000');
XID? ? ? ? ? ? ? START_SCN COMMIT_SCN ROW_ID? ? ? ? ? ? ? OPERATION? ? ? ? ? ? ? ? ? ? ? ? UNDO_SQL
---------------- ---------- ---------- ------------------- -------------------------------- --------------------------------------------------------------------------------
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAN? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? insert into "SYS"."TEST"("EMPNO","SAL") values ('7934','1300');
060016002F060000? ? 1940047? ? 1940079 AAAV4EAABAAARfpAAM? DELETE? ? ? ? ? ? ? ? ? ? ? ? ? ?
（篇幅原因，有省略……）
15 rows selected
Executed in 0.094 seconds
从10s到0.09s，这就是巨大的性能差异。我们可以从执行计划角度分析一下原因。
SQL> explain plan for select xid, start_scn, commit_scn, row_id, operation,undo_sql from flashback_transaction_query where xid='060016002F060000';
Explained
Executed in 0.172 seconds
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 1115820779
------------------------------------------------------------------------------
| Id? | Operation? ? ? ? | Name? ? ? | Rows? | Bytes | Cost (%CPU)| Time? ? |
------------------------------------------------------------------------------
|? 0 | SELECT STATEMENT |? ? ? ? ? |? ? 1 |? 2063 |? ? 0? (0)| 00:00:01 |
|*? 1 |? FIXED TABLE FULL| X$KTUQQRY |? ? 1 |? 2063 |? ? 0? (0)| 00:00:01 |
---------------------------------------------------------