Oracle教程 2023-03-28

Oracle 视图 V$BLOCK_CHANGE_TRACKING 官方解释，作用，如何使用详细说明

Oracle视图V$BLOCK_CHANGE_TRACKING是性能分析模块V$DIAGNOSTIC_BASE下的一种，查看它可以获取数据库中打开块更改跟踪的发生情况和状态信息。这个视图可以准确统计出各个数据文件最近的块更改次数，从而帮助DBAs了解哪些对象比较活跃，从而更好地实施优化。

在使用V$BLOCK_CHANGE_TRACKING查看数据库情况时，我们需要先确认数据库的块更改跟踪是否打开，若没有打开，则可以使用以下命令来打开：
ALTER DATABASE ENABLE BLOCK CHANGE TRACKING;

然后可以使用如下命令来查看：
SELECT * FROM V$BLOCK_CHANGE_TRACKING;

V$BLOCK_CHANGE_TRACKING displays the status of block change tracking for the database.

Column	Datatype	Description
`STATUS`	`VARCHAR2(10)`	Status of block change tracking in the database: `DISABLED` – Block change tracking is disabled `TRANSITION` – Block change tracking is in the process of transitioning between the enabled and disabled states. The `TRANSITION` state should usually never be observed, because it only exists while enabling or disabling block change tracking. This state might be observed if the instance crashed while enabling or disabling block change tracking, in which case it will be cleaned up automatically the next time that the database is opened. `ENABLED` – Block change tracking is enabled
`FILENAME`	`VARCHAR2(513)`	Name of the block change tracking file for the database
`BYTES`	`NUMBER`	Size of the block change tracking file (in bytes)
`CON_ID`	`NUMBER`	The ID of the container to which the data pertains. Possible values include: `0`: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs. `1`: This value is used for rows containing data that pertain to only the root n: Where n is the applicable container ID for the rows containing data