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) |