[Oracle] oracle 开启关闭Block Change Tracking

0、Block Change Tracking功能

默认情况下Block Change Tracking是被禁用的，该功能通过读取小的位图文件来决定哪个块改变了，在增量备份的过程中，开启这个功能可以避免扫面所有的数据文件，加快备份效率。

1、检查是否开启Block Change Tracking

19:38:00 SYS@ boston> COL STATUS   FORMAT A8
19:38:06 SYS@ boston> COL FILENAME FORMAT A60
19:38:08 SYS@ boston> SELECT STATUS, FILENAME FROM   V$BLOCK_CHANGE_TRACKING;

STATUS   FILENAME
-------- ------------------------------------------------------------
DISABLED

2、开启block change tracking

设置 DB_CREATE_FILE_DEST参数
SHOW PARAMETER DB_CREATE_FILE_DEST

19:38:28 SYS@ boston> SHOW PARAMETER DB_CREATE_FILE_DEST
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_create_file_dest                  string

如果db_create_file_dest参数没有设置，可以使用下面命令设置
ALTER SYSTEM SET DB_CREATE_FILE_DEST = '/home/oracle/' SCOPE=BOTH SID='*';

19:40:40 SYS@ boston> ALTER SYSTEM SET DB_CREATE_FILE_DEST = '/home/oracle/' SCOPE=BOTH SID='*';
System altered.

Elapsed: 00:00:00.12
19:41:48 SYS@ boston> SHOW PARAMETER DB_CREATE_FILE_DEST

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_create_file_dest                  string      /home/oracle/

设置完成db_create_file_dest参数之后，开启block change tracking

ALTER DATABASE ENABLE BLOCK CHANGE TRACKING;

19:41:51 SYS@ boston> ALTER DATABASE ENABLE BLOCK CHANGE TRACKING;
Database altered.
Elapsed: 00:00:04.49
19:44:18 SYS@ boston> SELECT STATUS, FILENAME FROM   V$BLOCK_CHANGE_TRACKING;
STATUS   FILENAME
-------- ------------------------------------------------------------
ENABLED  /home/oracle/BOSTON/changetracking/o1_mf_gc678fqg_.chg
Elapsed: 00:00:00.00

如果没有指定db_create_file_dest参数，也可以在开启block change tracking参数时指定
ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE '/tmp/rman_change_track.f' REUSE;

19:46:20 SYS@ boston> ALTER DATABASE DISABLE BLOCK CHANGE TRACKING;
Database altered.
Elapsed: 00:00:01.35
19:46:57 SYS@ boston> ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE '/tmp/rman_change_track.f' REUSE;
Database altered.
Elapsed: 00:00:05.02
19:47:03 SYS@ boston> SELECT STATUS, FILENAME FROM   V$BLOCK_CHANGE_TRACKING;
STATUS   FILENAME
-------- ------------------------------------------------------------
ENABLED  /tmp/rman_change_track.f
Elapsed: 00:00:00.00

3、禁用Block Change Tracking

ALTER DATABASE DISABLE BLOCK CHANGE TRACKING;

4、改变Block Change Tracking File位置

方法1：在不关闭数据库的情况下修改文件位置，可使用下面方法：

ALTER DATABASE DISABLE BLOCK CHANGE TRACKING;
ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE '/tmp/rman_change_track.f' REUSE;

这种方法会丢失已经存在的Block Change Tracking File，要想不丢失Block Change Tracking File需要使用下面方法

方法2：查看Block Change Tracking File原来的位置：

SELECT FILENAME FROM V$BLOCK_CHANGE_TRACKING;

19:52:19 SYS@ boston> SELECT FILENAME FROM V$BLOCK_CHANGE_TRACKING;
FILENAME
------------------------------------------------------------
/tmp/rman_change_track.f

关闭数据库
SHUTDOWN IMMEDIATE
操作系统下拷贝物理文件到新的目标路径
mv /tmp/rman_change_track.f /home/oracle/new_rman_change_track.f
启动数据库到mount
startup mount
修改Block Change Tracking File
ALTER DATABASE RENAME FILE '/tmp/rman_change_track.f' TO '/home/oracle/new_rman_change_track.f';
打开数据库
ALTER DATABASE OPEN;
查看Block Change Tracking File的文件路径

20:03:18 SYS@ boston> SELECT FILENAME FROM V$BLOCK_CHANGE_TRACKING;
FILENAME
----------------------------------------------------------------------------------------------------------------------------------
/home/oracle/new_rman_change_track.f