Oracle教程 2023-03-31

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

表显示历史 I/O活动的文件性能指标数据

Oracle视图是一种特殊的内部数据存储结构，可以用来存储和检索数据，允许用户通过SQL语句查询视图中的信息而无需了解其存储内部结构。

V$FILEMETRIC_HISTORY视图可以用来查看历史I/O活动的文件性能指标数据。它会显示最近在Oracle实例中文件中进行的I/O活动的时间和相关数据，并且会将这些数据按指标分类，如平均服务时间和读/写的次数等。

使用V$FILEMETRIC_HISTORY视图的一个例子是，当某一文件访问多次时，可以使用这个视图来查看每次访问的所有参数，其中包括每次访问消耗的总时间以及I/O数量等。用户可以根据这些参数来优化文件访问，并实现最佳的性能效果。

V$FILEMETRIC_HISTORY displays values of file metrics for all intervals in the last one hour.

Column	Datatype	Description
`BEGIN_TIME`	`DATE`	Begin time of the interval
`END_TIME`	`DATE`	End time of the interval
`INTSIZE_CSEC`	`NUMBER`	Interval size (in hundredths of a second)
`FILE_ID`	`NUMBER`	File number
`CREATION_TIME`	`NUMBER`	Timestamp of the file creation
`AVERAGE_READ_TIME`	`NUMBER`	Average file read time (in hundredths of a second)
`AVERAGE_WRITE_TIME`	`NUMBER`	Average file write time (in hundredths of a second)
`PHYSICAL_READS`	`NUMBER`	Number of physical reads
`PHYSICAL_WRITES`	`NUMBER`	Number of physical writes
`PHYSICAL_BLOCK_READS`	`NUMBER`	Number of physical block reads
`PHYSICAL_BLOCK_WRITES`	`NUMBER`	Number of physical block writes
`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

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