Flashback Data Archive 闪回归档测试

DML闪回特性，使用UNDO表空间，由于UNDO表空间的信息总会丢失（undo_retention不可能设置无限大），所以Oracle database 11g开始，Oracle提供了闪回数据归档(Flashback Data Archive)功能。通过此通过，可以使数据库对UNDO数据进行归档，从而提供长时间历史数据查询功能 。Oracle database 11g新增的后台进程FBDA(Flashback Data Archiver Process)用于对闪回数据进行归档写出操作。闪回归档需要独立存储空间，在使用该特性之前启动ASSM。

一、创建闪回空间

SQL> create tablespace fbra datafile '/u01/app/oracle/oradata/orcl/fbra01.dbf' size 100m autoextend on segment space management auto;

Tablespace created.

二、创建闪回归档

SQL> create flashback archive dataarchive tablespace fbra retention 1 month;

Flashback archive created.

三、为测试闪回归档，减小UNDO表空间，关闭自动扩展属性

SQL> alter database datafile '/u01/app/oracle/oradata/orcl/undotbs01.dbf' resize 100m;

Database altered.

SQL> alter database datafile '/u01/app/oracle/oradata/orcl/undotbs01.dbf' autoextend off;

Database altered.

四、连接到测试用户，并在相关表上启用FLASHBACK ARCHIVE对象权限（ create table jerry_copy as select * from dba_objects）

SQL> conn jerry/jerry;

Connected.

SQL> alter table jerry_copy flashback archive dataarchive;

Table altered.

五、获得系统当前SCN：

SQL> select dbms_flashback.get_system_change_number from dual;

GET_SYSTEM_CHANGE_NUMBER

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

9104236

六、查询前期创建的表

SQL> select count(*) from jerry_copy;

COUNT(*)

----------

72828

SQL> delete from jerry_copy where rownum < 10000;

9999 rows deleted.

SQL> commit;

Commit complete.

七、执行删除语句，使undo表空间数据写入归档。

SQL> begin

2 for i in 1..10000 loop

3 delete from jerry_copy where rownum < 1;

4 commit;

5 end loop;

6 end;

7 /

PL/SQL procedure successfully completed.

八、启用跟踪

SQL> set autotrace on;

九、查看执行计划，查询表

SQL> select count(*) from jerry_copy as of scn 9104236;

COUNT(*)

----------

72828

Execution Plan

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

Plan hash value: 1326699257

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |

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

| 0 | SELECT STATEMENT | | 1 | | 1172 (1)| 00:00:15 | | |

| 1 | SORT AGGREGATE | | 1 | | | | | |

| 2 | VIEW | | 14223 | | 1172 (1)| 00:00:15 | | |

| 3 | UNION-ALL | | | | | | | |

| 4 | PARTITION RANGE SINGLE| | 10582 | 268K| 25 (0)| 00:00:01 | 1 | 1 |

|* 5 | TABLE ACCESS FULL | SYS_FBA_HIST_76492 | 10582 | 268K| 25 (0)| 00:00:01 | 1 | 1 |

|* 6 | FILTER | | | | | | | |

|* 7 | HASH JOIN OUTER | | 3641 | 7253K| 1147 (1)| 00:00:14 | | |

|* 8 | TABLE ACCESS FULL | JERRY_COPY | 3641 | 43692 | 1128 (1)| 00:00:14 | | |

|* 9 | TABLE ACCESS FULL | SYS_FBA_TCRV_76492 | 10139 | 19M| 19 (0)| 00:00:01 | | |

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

Predicate Information (identified by operation id):

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

5 - filter("ENDSCN">9104236 AND "ENDSCN"<=9108963 AND ("STARTSCN" IS NULL OR "STARTSCN"<=9104236))

6 - filter("STARTSCN"<=9104236 OR "STARTSCN" IS NULL)

7 - access("T".ROWID=CHARTOROWID("RID"(+)))

8 - filter("T"."VERSIONS_STARTSCN" IS NULL)

9 - filter(("ENDSCN"(+) IS NULL OR "ENDSCN"(+)>9108963) AND ("STARTSCN"(+) IS NULL OR

"STARTSCN"(+)<9108963))

Note

-----

- dynamic sampling used for this statement (level=2)

Statistics

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

28 recursive calls

0 db block gets

327 consistent gets

0 physical reads

0 redo size

424 bytes sent via SQL*Net to client

419 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

1 sorts (memory)

0 sorts (disk)

1 rows processed

SQL> col TABLE_NAME for a40;

SQL> col OWNER_NAME for a50;

SQL> col FLASHBACK_ARCHIVE_NAME for a40;

SQL> col ARCHIVE_TABLE_NAME for a30;

SQL> set autotrace off;

十、查看数据字典查询关于闪回归档表的记录

SQL> select * from user_flashback_archive_tables;

TABLE_NAME OWNER_NAME FLASHBACK_ARCHIVE_NAME ARCHIVE_TABLE_NAME STATUS

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

JERRY_COPY JERRY DATAARCHIVE SYS_FBA_HIST_76492 ENABLED

十一、查看闪回功能生成的字典对象

SQL> select u.table_name, u.tablespace_name from user_tables u where u.table_name like '%FBA%';

TABLE_NAME TABLESPACE_NAME

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

SYS_FBA_DDL_COLMAP_76492 FBRA

SYS_FBA_TCRV_76492 FBRA

SYS_FBA_HIST_76492

十二、查询和闪回归档相关的数据字典表

SQL> col COMMENTS for a80;

SQL> select * from dict where table_name like '%FLASHBACK_ARCHIVE%';

TABLE_NAME COMMENTS

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

DBA_FLASHBACK_ARCHIVE Description of the flashback archives available in the system

DBA_FLASHBACK_ARCHIVE_TABLES Information about the tables that are enabled for Flashback Archive

DBA_FLASHBACK_ARCHIVE_TS Description of tablespaces in the flashback archives available in the system

USER_FLASHBACK_ARCHIVE Description of the flashback archives available to the user

USER_FLASHBACK_ARCHIVE_TABLES Information about the user tables that are enabled for Flashback Archive

十二、测试完成，取消在表上的闪回归档

SQL> alter table jerry_copy no flashback archive;

Table altered.

十三、恢复UNDO表空间自动扩展属性

SQL> conn / as sysdba;

SQL> alter database datafile '/u01/app/oracle/oradata/orcl/undotbs01.dbf' autoextend on;

Database altered.