Oracle教程 2023-03-28

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

本站中文解释

Oracle视图V$CON_EVENT_HISTOGRAM_MICRO提供了一种独特的方法来查看微观级别的活动统计信息，其中包括保存了每个会话最近每个版本的所有活动的统计数据，以及每个活动的统计数据。有了这些数据，系统运行团队可以确定系统上发生的每个活动，从而帮助他们改善系统性能。

使用V$CON_EVENT_HISTOGRAM_MICRO可以检测性能瓶颈，识别性能问题。它可以提供以下信息：

1.排队等待事件:统计每个连接的排队等待情况以提供有关可能存在性能问题的信息。

2.每个活动的CPU使用情况:根据活动类型，该视图统计出每个连接的CPU使用情况。这可以优化系统性能，帮助总结出哪些活动在消耗大量CPU资源。

3.每个活动的IO使用情况：该视图统计出每个连接的IO使用情况，以帮助检测磁盘瓶颈。

使用该视图可以更容易了解连接活动信息，如果发现有吞吐量低的活动，并且有明显的消耗大量CPU资源，那么可以采取相应的措施来改善性能。

使用Oracle视图V$CON_EVENT_HISTOGRAM_MICRO的步骤：

1.使用完整的查询语句：SELECT * FROM V$CON_EVENT_HISTOGRAM_MICRO;

2.针对特定会话，输入会话ID：SELECT * FROM V$CON_EVENT_HISTOGRAM_MICRO WHERE sid=?;

3.查看某一种特定类型的活动：SELECT * FROM V$CON_EVENT_HISTOGRAM_MICRO WHERE event_name=’wait for free buffer’;

4.根据时间跨度查询：SELECT * FROM V$CON_EVENT_HISTOGRAM_MICRO WHERE timestamp >= SYSDATE-1/24;

要使用V$CON_EVENT_HISTOGRAM_MICRO视图，你需要连接到Oracle数据库，并使用正确的权限运行查询。

官方英文解释

V$CON_EVENT_HISTOGRAM_MICRO displays a histogram of the number of waits, the maximum wait, and total wait time on an event basis for a container, in microseconds. The histogram has buckets of time intervals from < 1 us, < 2 us, < 4 us, < 8 us, … < 2³¹ us, < 2³² us, and >= 2³² us.

The histogram will not be filled unless the TIMED_STATISTICS initialization parameter is set to true.

Column	Datatype	Description
`EVENT#`	`NUMBER`	Event number
`EVENT`	`VARCHAR2(64)`	Name of the event
`WAIT_TIME_FORMAT`	`VARCHAR2(30)`	A human readable time string which is converted from `WAIT_TIME_MICRO`. When `WAIT_TIME_MICRO` < 1 millisecond, `WAIT_TIME_FORMAT` is shown in microseconds. When `WAIT_TIME_MICRO` < 1 second, `WAIT_TIME_FORMAT` is shown in milliseconds. When `WAIT_TIME_MICRO` < 1 minute, `WAIT_TIME_FORMAT` is shown in seconds. When `WAIT_TIME_MICRO` > 1 minute, `WAIT_TIME_FORMAT` is shown in minutes and seconds.
`WAIT_TIME_MICRO`	`NUMBER`	Amount of time the bucket represents (in microseconds). If the duration = `num`, then this column represents waits of duration < `num` that are not included in any smaller bucket.
`WAIT_COUNT`	`NUMBER`	Number of waits of the duration belonging to the bucket of the histogram
`LAST_UPDATE_TIME`	`VARCHAR2(73)`	Indicates the last time the bucket was updated (the ending timestamp of the last wait falling into the bucket’s duration)
`CON_ID`	`NUMBER`	When queried from a non-CDB, the wait event data in that instance are returned, and the `CON_ID` value is `0`. When queried from the root of a CDB, the wait event data in every container is returned, and the `CON_ID` value indicates the container to which the wait event data belong. When queried from a PDB, wait event data in that PDB are returned, and the `CON_ID` value is the container ID for that PDB.

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

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