Oracle 视图 DBA_HIST_WAITCLASSMET_HISTORY 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_WAITCLASSMET_HISTORY是属于Oracle数据库，用于分析等待事件分类的历史性能指标。查看DBA_HIST_WAITCLASSMET_HISTORY视图，可能会显示以下列：SNAP_ID，TIMESTAMP，EVENT_CLASS，TOTAL_WAITS，TOTAL_TIMEOUTS，TIME_WAITED，AVG_WAIT，MAX_WAIT等。
可以通过以下语句使用它：SELECT * FROM DBA_HIST_WAITCLASSMET_HISTORY WHERE SNAP_ID=?; 其中，?为用户需要查看的快照ID号。
此外，也可以使用以下针对性聚合函数来查看某一具体等待事件分类的性能指标：SELECT AVG_WAIT FROM DBA_HIST_WAITCLASSMET_HISTORY WHERE EVENT_CLASS=?; 其中，?为待查看的等待事件分类名称。
官方英文解释
DBA_HIST_WAITCLASSMET_HISTORY displays the history of the wait event class metric data kept by the Workload Repository.
| Column | Datatype | NULL | Description |
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Unique snapshot ID |
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Database ID of the snapshot |
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Instance number of the snapshot |
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Identifier of the class of the wait event |
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Name of the class of the wait event |
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Begin time of the interval |
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End time of the interval |
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Interval size (in hundredths of a second) |
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Metric group ID |
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Average waiter count |
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Percent of database time spent in the wait |
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Time waited during the interval (in microseconds) |
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Number of times waited |
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Time waited (in hundredths of a second), from foreground sessions |
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Number of times waited, from foreground sessions |
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The database ID of the PDB for the sampled session |
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The ID of the container that
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