Oracle教程 2023-03-21

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

本站中文解释

V$DATAFILE_HEADER是Oracle数据库中的一个视图，它可以提供有关每个表空间数据文件的信息。可以回答的问题包括：每个表空间中有多少数据文件？每个数据文件的位置是什么？数据文件的大小？数据文件的状态是什么？

使用V$DATAFILE_HEADER视图的方法：

1、查询每个表空间中有多少数据文件：

SELECT TABLESPACE_NAME, COUNT(*) FROM V$DATAFILE_HEADER GROUP BY TABLESPACE_NAME;

2、查询每个数据文件的详细信息，包括位置、大小以及状态：

SELECT * FROM V$DATAFILE_HEADER;

官方英文解释

V$DATAFILE_HEADER displays data file information from the data file headers.

Column	Datatype	Description
`FILE#`	`NUMBER`	Data file number (from control file)
`STATUS`	`VARCHAR2(7)`	`ONLINE` \| `OFFLINE` (from control file)
`ERROR`	`VARCHAR2(18)`	NULL if the data file header read and validation were successful. If the read failed then the rest of the columns are NULL. If the validation failed then the rest of columns may display invalid data. If there is an error then usually the data file must be restored from a backup before it can be recovered or used.
`FORMAT`	`NUMBER`	Indicates the format for the header block. The possible values are `6,` `7`, `8`, `10` or `0`. `6` – indicates Oracle Version 6 `7` – indicates Oracle Version 7 `8` – indicates Oracle Version 8 `10` – indicates Oracle Version 10 `0` – indicates the format could not be determined (for example, the header could not be read)
`RECOVER`	`VARCHAR2(3)`	File needs media recovery (`YES` \| `NO`)
`FUZZY`	`VARCHAR2(3)`	File is fuzzy (`YES` \| `NO`)
`CREATION_CHANGE#`	`NUMBER`	Data file creation change#
`CREATION_TIME`	`DATE`	Data file creation timestamp
`TABLESPACE_NAME`	`VARCHAR2(30)`	Tablespace name
`TS#`	`NUMBER`	Tablespace number
`RFILE#`	`NUMBER`	Tablespace relative data file number
`RESETLOGS_CHANGE#`	`NUMBER`	Resetlogs change#
`RESETLOGS_TIME`	`DATE`	Resetlogs timestamp
`CHECKPOINT_CHANGE#`	`NUMBER`	Data file checkpoint change#
`CHECKPOINT_TIME`	`DATE`	Data file checkpoint timestamp
`CHECKPOINT_COUNT`	`NUMBER`	Data file checkpoint count
`BYTES`	`NUMBER`	Current data file size in bytes
`BLOCKS`	`NUMBER`	Current data file size in blocks
`NAME`	`VARCHAR2(513)`	Data file name
`SPACE_HEADER`	`VARCHAR2(40)`	Represents the block address of a space file header block of a locally managed data file
`LAST_DEALLOC_CHANGE#`	`VARCHAR2(16)`	Last deallocated SCN
`UNDO_OPT_CURRENT_CHANGE#`	`VARCHAR2(40)`	For internal use only
`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
`IS_SPARSE`	`VARCHAR2(3)`	Indicates whether the file is sparse (`YES`) or not (`NO`)
`ENCRYPTED`	`VARCHAR2(3)`	After file encryption is completed, this column indicates whether the file is encrypted (`YES`) or not (`NO`). When file encryption is still in progress, this column has a value of `NO`.

数据运维技术 » Oracle 视图 V$DATAFILE_HEADER 官方解释，作用，如何使用详细说明

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