Oracle教程 2023-03-21

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

该视图仅用于可以收集的以下类型的系统指标汇总信息的查询：

1)资源使用情况：根据该视图可以查看数据库实例的资源使用情况，包括CPU、缓存调用、缓存大小等。

2)归档日志量：通过该视图可以查看数据库实例的归档日志量，包括全部归档和近期归档日志量。

3)活动数据文件：该视图可以显示数据库实例当前活动数据文件的数量及使用量。

4)会话：DBA_HIST_SYSMETRIC_SUMMARY视图也可以查询数据库实例当前的会话数量，以及会话的平均时长等信息。

使用Oracle视图的步骤：

(1)连接到Oracle数据库，使用拥有足够权限的用户账号登录。

(2)查询DBA_HIST_SYSMETRIC_SUMMARY视图，使用SELECT 语句，例如：SELECT * FROM DBA_HIST_SYSMETRIC_SUMMARY；

(3)为查询添加过滤条件，以缩小数据检索范围，例如：SELECT * FROM DBA_HIST_SYSMETRIC_SUMMARY WHERE DBID = {instance_number} AND SNAP_ID = {snap_id};

(4)执行查询语句，通过浏览返回的数据，获得有关数据库实例的系统指标汇总信息。

DBA_HIST_SYSMETRIC_SUMMARY displays a history of statistical summary of all metric values in the System Metrics Long Duration group.

This view contains snapshots of V$SYSMETRIC_SUMMARY.

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
`BEGIN_TIME`	`DATE`	`NOT NULL`	Begin time of the interval
`END_TIME`	`DATE`	`NOT NULL`	End time of the interval
`INTSIZE`	`NUMBER`	`NOT NULL`	Interval size (in hundredths of a second)
`GROUP_ID`	`NUMBER`	`NOT NULL`	Group ID
`METRIC_ID`	`NUMBER`	`NOT NULL`	Metric ID
`METRIC_NAME`	`VARCHAR2(64)`	`NOT NULL`	Metric name
`METRIC_UNIT`	`VARCHAR2(64)`	`NOT NULL`	Unit of measurement
`NUM_INTERVAL`	`NUMBER`	`NOT NULL`	Number of intervals observed
`MINVAL`	`NUMBER`	`NOT NULL`	Minimum value observed
`MAXVAL`	`NUMBER`	`NOT NULL`	Maximum value observed
`AVERAGE`	`NUMBER`	`NOT NULL`	Average over the period
`STANDARD_DEVIATION`	`NUMBER`	`NOT NULL`	One standard deviation
`SUM_SQUARES`	`NUMBER`		Sum of the squared deviations from the mean
`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