Oracle教程 2023-02-24

Oracle 视图 DBA_HIST_IOSTAT_FUNCTION 官方解释，作用，如何使用详细说明

本站中文解释

Oracle视图DBA_HIST_IOSTAT_FUNCTION是数据库管理员用于查看I/O统计历史信息的视图，主要用于记录数据库中某段时间内每个节点的I/O状态、每种I/O状态的时间长度，以及每种I/O状态的总时长。数据库管理员可以通过这个视图分析I/O状态情况，早期发现系统中的I/O性能瓶颈，并采取相应的措施调优。

使用DBA_HIST_IOSTAT_FUNCTION视图的方法：

1. 查询当前节点上某段时间内每一种I/O状态的详细信息：

SELECT * FROM DBA_HIST_IOSTAT_FUNCTION WHERE NODE_NUMBER = ‘当前节点编号’ AND SNAP_ID BETWEEN ‘开始时间’ AND ‘结束时间’;

2. 查询某段时间内，每个节点总的I/O时间：

SELECT NODE_NUMBER, SUM(CON_DB_TIME)AS TOTAL_IO_TIME FROM DBA_HIST_IOSTAT_FUNCTION WHERE SNAP_ID BETWEEN ‘开始时间’ AND ‘结束时间’ GROUP BY NODE_NUMBER;

3. 查询某段时间内每一节点，每一种I/O状态的时间比例：

SELECT NODE_NUMBER, FUNCTION_STATUS, SUM(CON_DB_TIME)AS TOTAL_IO_TIME, ROUND(SUM(CON_DB_TIME)/ SUM(OVER(FUNCTION_STATUS)) * 100, 2 )AS IO_STATUS_RATIO FROM DBA_HIST_IOSTAT_FUNCTION WHERE SNAP_ID BETWEEN ‘开始时间’ AND ‘结束时间’ GROUP BY NODE_NUMBER, FUNCTION_STATUS;

官方英文解释

DBA_HIST_IOSTAT_FUNCTION displays historical I/O statistics by function.

This view contains snapshots of V$IOSTAT_FUNCTION.

Column	Datatype	NULL	Description
`SNAP_ID`	`NUMBER`	`NOT NULL`	Unique snapshot ID
`DBID`	`NUMBER`	`NOT NULL`	Database ID for the snapshot
`INSTANCE_NUMBER`	`NUMBER`	`NOT NULL`	Instance number for the snapshot
`FUNCTION_ID`	`NUMBER`	`NOT NULL`	Function ID
`FUNCTION_NAME`	`VARCHAR2(128)`	`NOT NULL`	Function name
`SMALL_READ_MEGABYTES`	`NUMBER`	`NOT NULL`	Number of single block megabytes read
`SMALL_WRITE_MEGABYTES`	`NUMBER`	`NOT NULL`	Number of single block megabytes written
`LARGE_READ_MEGABYTES`	`NUMBER`	`NOT NULL`	Number of multiblock megabytes read
`LARGE_WRITE_MEGABYTES`	`NUMBER`	`NOT NULL`	Number of multiblock megabytes written
`SMALL_READ_REQS`	`NUMBER`	`NOT NULL`	Number of single block read requests
`SMALL_WRITE_REQS`	`NUMBER`	`NOT NULL`	Number of single block write requests
`LARGE_READ_REQS`	`NUMBER`	`NOT NULL`	Number of multiblock read requests
`LARGE_WRITE_REQS`	`NUMBER`	`NOT NULL`	Number of multiblock write requests
`NUMBER_OF_WAITS`	`NUMBER`	`NOT NULL`	Number of I/O waits by functionality
`WAIT_TIME`	`NUMBER`	`NOT NULL`	Total wait time (in milliseconds)
`CON_DBID`	`NUMBER`		The database ID of the PDB for the sampled session
`CON_ID`	`NUMBER`		The ID of the container that `CON_DBID` identifies. 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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