V$EVENT_HISTOGRAM

V$EVENT_HISTOGRAM displays a histogram of the number of waits, the maximum wait, and total wait time on an event basis. The histogram has buckets of time intervals from < 1 ms, < 2 ms, < 4 ms, < 8 ms, ... < 2²¹ ms, < 2²² ms, and >= 2²² ms.

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_MILLI`	`NUMBER`	Amount of time the bucket represents (in milliseconds). 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(64)`	Indicates the last time the bucket was updated (the ending timestamp of the last wait falling into the bucket's duration)