闪加查询、闪回版本查询、闪回事务查询

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1.闪回查询：

步骤是记录当前SCN及时间，然后进行DML操作，提交后使用 timestamp和SCN进行对DML操作之前数据的查询

SQL> set time on;
19:13:57 SQL> insert into test select rownum from dual connect by rownum<=5;
5 rows inserted
19:14:47 SQL> commit;
Commit complete
19:14:49 SQL> select dbms_flashback.get_system_change_number from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
                 1362061
19:18:11 SQL> delete test where a>2;
3 rows deleted
19:18:17 SQL> commit;
Commit complete
19:21:56 SQL> select * from test as of timestamp to_timestamp('2013/06/23 19:17:00','yyyy/mm/dd hh24:mi:ss');
         A
----------
         2
         3
         4
         5
         1
19:24:23 SQL> select * from test as of scn 1362061;
         A
----------
         2
         3
         4
         5

2.闪回查询--查询的是已经提交的数据

因为闪回查询的是已经提交的，这样即使数据未提交而数据库SHUTDOWN ABORT，重启后因为做实例恢复，使用闪回所查询的数据仍是已经提交的。

实验过程：查询当前SCN并执行DML操作不提交并查询当前SCN，使用闪回查询功能查询DML操作之前和之后的SCN

结果是：验证闪回查询返回的是已经提交的数据。

20:22:44 BYS@bys1>select * from test3;
        ID NAME
---------- ----------
         2 b
20:22:48 BYS@bys1>select current_scn from v$database;
CURRENT_SCN
-----------
    1741868
20:26:17 BYS@bys1>delete test3;   ---不提交
1 row deleted.

各种查询：

20:26:26 BYS@bys1>select * from test3;
no rows selected
20:26:29 BYS@bys1>select current_scn from v$database;
CURRENT_SCN
-----------
    1741881
20:26:50 BYS@bys1>select * from test3 as of scn 1741868;
        ID NAME
---------- ----------
         2 b
20:27:10 BYS@bys1>select * from test3 as of scn 1741881;
        ID NAME
---------- ----------
         2 b

3.闪回版本查询

versions_operation:   操作类型
versions_xid:   事务编号
versions_starttime:   开始时间
versions_endtime:   结束时间，如果有值，证明这记录已非当前记录
versions_startscn:   开始SCN号

versions_endscn: 结束SCN号如果有值，证明这记录已非当前记录

操作步骤：

19:25:28 SQL> select dbms_flashback.get_system_change_number from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
                 1362268
19:37:09 SQL> col versions_starttime for a25
19:37:22 SQL> col versions_endtime for a25
19:38:02 SQL> select versions_startscn,versions_starttime, versions_endtime, versions_operation,versions_xid from test versions between timestampto_timestamp('2013/06/2319:17:00','yyyy/mm/dd hh24:mi:ss')and to_timestamp('2013/06/2319:20:00','yyyy/mm/dd hh24:mi:ss');

VERSIONS_STARTSCN VERSIONS_STARTTIME        VERSIONS_ENDTIME          VERSIONS_OPERATION VERSIONS_XID
----------------- ------------------------- ------------------------- ------------------ ----------------
          1362122 23-JUN-13 07.19.48 PM                               D                  04001200C8020000
          1362122 23-JUN-13 07.19.48 PM                               D                  04001200C8020000
          1362122 23-JUN-13 07.19.48 PM                               D                  04001200C8020000
                                            23-JUN-13 07.19.48 PM
                                            23-JUN-13 07.19.48 PM
                                            23-JUN-13 07.19.48 PM
8 rows selected

4.闪回事务查询

闪回事务查询需要打开追加日志，不然无法从 flashback_transaction_query查出UNDO_SQL

20:35:42 SQL> show parameter undo

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      AUTO
undo_retention                       integer     900
undo_tablespace                      string      UNDOTBS1
20:35:57 SQL> alter database add supplemental log data;
Database altered.
20:38:01 SQL> select * from test;
         A
----------
         2
         3
         1
20:38:24 SQL> update test set a=a+10;
3 rows updated.
20:38:36 SQL> commit;
Commit complete.
20:39:37 SQL> col versions_endtime for a20
20:40:25 SQL> col versions_starttime for a20
20:40:36 SQL> set pagesize 100
20:41:56 SQL> select versions_startscn,versions_starttime, versions_endtime, versions_operation,versions_xid from test versions between timestamp to_timestamp('2013/06/23 20:38:00','yyyy/mm/dd hh24:mi:ss') and to_timestamp('2013/06/23 20:39:00','yyyy/mm/dd hh24:mi:ss');

VERSIONS_STARTSCN VERSIONS_STARTTIME   VERSIONS_ENDTIME     V VERSIONS_XID
----------------- -------------------- -------------------- - ----------------
          1369588 23-JUN-13 08.38.41 PM                      U 060001003A030000
          1369588 23-JUN-13 08.38.41 PM                      U 060001003A030000
          1369588 23-JUN-13 08.38.41 PM                      U 060001003A030000
                                       23-JUN-13 08.38.41 PM
                                       23-JUN-13 08.38.41 PM
                                       23-JUN-13 08.38.41 PM
6 rows selected.
20:41:57 SQL> col operation for a10
20:43:07 SQL> col undo_sql for a60
20:43:20 SQL> select operation,undo_sql from flashback_transaction_querywhere logon_user='BYS' andundo_sql like '%TEST%';
OPERATION UNDO_SQL
---------- ------------------------------------------------------------
UPDATE     update "BYS"."TEST" set "A" = '1' where ROWID = 'AAASYyAAEAA
           AAcjAKR';
UPDATE     update "BYS"."TEST" set "A" = '3' where ROWID = 'AAASYyAAEAA
           AAcjAAE';
UPDATE     update "BYS"."TEST" set "A" = '2' where ROWID = 'AAASYyAAEAA
           AAcjAAA';
20:44:12 SQL> select operation,undo_sql from flashback_transaction_query where logon_user='BYS' and undo_sql like '%TEST%' andxid=HEXTORAW('060001003A030000');
OPERATION UNDO_SQL
---------- ------------------------------------------------------------
UPDATE     update "BYS"."TEST" set "A" = '1' where ROWID = 'AAASYyAAEAA
           AAcjAKR';
UPDATE     update "BYS"."TEST" set "A" = '3' where ROWID = 'AAASYyAAEAA
           AAcjAAE';
UPDATE     update "BYS"."TEST" set "A" = '2' where ROWID = 'AAASYyAAEAA
           AAcjAAA';
可以使用XID做为条件：
20:45:01 SQL> select operation,undo_sql from flashback_transaction_querywhere xid=HEXTORAW('060001003A030000');
OPERATION UNDO_SQL
---------- ------------------------------------------------------------
UPDATE     update "BYS"."TEST" set "A" = '1' where ROWID = 'AAASYyAAEAA
           AAcjAKR';
UPDATE     update "BYS"."TEST" set "A" = '3' where ROWID = 'AAASYyAAEAA
           AAcjAAE';
UPDATE     update "BYS"."TEST" set "A" = '2' where ROWID = 'AAASYyAAEAA
           AAcjAAA';
BEGIN
可以使用XID做为条件：
20:45:17 SQL> select operation,undo_sql from flashback_transaction_querywhere xid='060001003A030000';
OPERATION UNDO_SQL
---------- ------------------------------------------------------------
UPDATE     update "BYS"."TEST" set "A" = '1' where ROWID = 'AAASYyAAEAA
           AAcjAKR';
UPDATE     update "BYS"."TEST" set "A" = '3' where ROWID = 'AAASYyAAEAA
           AAcjAAE';
UPDATE     update "BYS"."TEST" set "A" = '2' where ROWID = 'AAASYyAAEAA
           AAcjAAA';
BEGIN