Oracle 9i引入的闪回查询功能显示前一个时间点的查询结果。但是,表本身并没有改变。 Oracle 10g 增强了闪回功能,可" />
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在Oracle 10gR2中设定指定的恢复点实现轻松闪回

来源:互联网 作者:佚名 时间:2015-10-13 21:03
欢迎进入Oracle社区论坛,与200万技术人员互动交流 >>进入 Oracle href="http://search.e800.com.cn/Oracle" target=_blank alt="Oracle"> Oracle 9i引入的闪回查询功能显示前一个时间点的查询结果。但是,表本身并没有改变。 Oracle 10g 增强了闪回功能,可
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Oracle href="http://search.e800.com.cn/Oracle" target=_blank alt="Oracle">Oracle 9i引入的闪回查询功能显示前一个时间点的查询结果。但是,表本身并没有改变。Oracle 10g增强了闪回功能,可以永久闪回一个表格。现在Oracle 10g第二版通过增加指定的恢复点,使这一过程更加方便。

存储

应用恢复点不必知道准确的SCN。恢复点建立后,它即恢复当前SCN。因此,使用恢复点名称等同于使用对应的SCN。

CREATE RESTORE POINT(创建恢复点)命令的语法很简单:

CREATE RESTORE POINT restore_point_name;

FLASHBACK ANY TABLE或SELECT ANY DICTIONARY权限需要建立一个正常(无保证)的恢复点。一旦恢复点不再需要,对应的DROP RESTORE POINT命令就将它删除。

列表A显示向OE模式提供的正确许可,建立一个恢复点,然后在一个错过正确WHERE子句的错误UPDATE后建立一个FLASHBACK TABLE。


SQL> CONNECT / AS SYSDBA

Connected.

SQL> GRANT SELECT ANY DICTIONARY TO oe;
Grant succeeded.
SQL> CONNECT OE/OE

Connected.
SQL> -- Tables must have row movement enabled to flash back

SQL> ALTER TABLE warehouses 2 ENABLE ROW MOVEMENT;
Table altered.
SQL> CREATE RESTORE POINT my_update;
Restore point created.
SQL> COLUMN name FORMAT a25

SQL> COLUMN time FORMAT a32

SQL>
SQL> SELECT name, scn, time,
guarantee_flashback_database 2 FROMv$restore_point;
NAME SCN TIME GUA

------------------------- ---------- ------------------------------

MY_UPDATE 734934 10-AUG-06 03.32.29.000000000 PM NO
SQL> UPDATE warehouses 2 SET warehouse_name = ''Bellevue, WA'';
9 rows updated.
SQL> COMMIT;
Commit complete.
SQL> SELECT warehouse_id, warehouse_name 2 FROM warehouses;
WAREHOUSE_ID WAREHOUSE_NAME

------------ -----------------------------------
1 Bellevue, WA 2 Bellevue, WA 3 Bellevue, WA 4 Bellevue,
WA 5 Bellevue, WA 6 Bellevue, WA 7 Bellevue, WA 8 Bellevue,
WA 9 Bellevue, WA 9 rows selected.SQL> CONNECT / AS SYSDBA Connected.

SQL> GRANT SELECT ANY DICTIONARY TO oe;
Grant succeeded.
SQL> CONNECT OE/OE

Connected.
SQL> -- Tables must have row movement enabled to flash back

SQL> ALTER TABLE warehouses 2 ENABLE ROW MOVEMENT;
Table altered.
SQL> CREATE RESTORE POINT my_update;
Restore point created.
SQL> COLUMN name FORMAT a25

SQL> COLUMN time FORMAT a32

SQL>
SQL> SELECT name, scn, time,
guarantee_flashback_database 2 FROMv$restore_point;
NAME SCN TIME GUA

------------------------- ---------- -------------------------------

MY_UPDATE 734934 10-AUG-06 03.32.29.000000000 PM NO
SQL> UPDATE warehouses 2 SET warehouse_name = ''Bellevue, WA'';
9 rows updated.
SQL> COMMIT;
Commit complete.
SQL> SELECT warehouse_id, warehouse_name 2 FROM warehouses;
WAREHOUSE_ID WAREHOUSE_NAME

------------ -----------------------------------
1 Bellevue, WA 2 Bellevue, WA 3 Bellevue,
WA 4 Bellevue, WA 5 Bellevue, WA 6 Bellevue, WA 7 Bellevue,
WA 8 Bellevue, WA 9 Bellevue, WA 9 rows selected.
SQL> FLASHBACK TABLE warehouses 2 TO RESTORE POINT my_update;
Flashback complete.
SQL> SELECT warehouse_id, warehouse_name 2 FROM warehouses;
WAREHOUSE_ID WAREHOUSE_NAME

------------ -----------------------------------
1 Southlake, Texas 2 San Francisco 3 New Jersey 4 Seattle,
Washington 5 Toronto 6 Sydney 7 Mexico City 8 Beijing 9 Bombay
9 rows selected.


SQL> FLASHBACK TABLE warehouses 2 TO RESTORE POINT my_update;
Flashback complete.
SQL> SELECT warehouse_id, warehouse_name 2 FROM warehouses;
WAREHOUSE_ID WAREHOUSE_NAME

------------ -----------------------------------
1 Southlake, Texas 2 San Francisco 3 New Jersey 4 Seattle,
Washington 5 Toronto 6 Sydney 7 Mexico City 8 Beijing 9 Bombay
9 rows selected.

列表A

恢复点存储在控制文件中,所以即使数据库关闭(安装好,但未开),它们仍然有效。这意味着你还可在FLASHBACK DATABASE命令中使用它们。

作者:Bob Watkins(OCP、MCDBA、MCSE、MCT)是一位有25年经验的计算机专业人士,从事过技术培训师、顾问与数据库管理员等职。

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