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Oracle® Database Reference
12c Release 1 (12.1)

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V$EVENT_HISTOGRAM_MICRO displays a histogram of the number of waits, the maximum wait, and total wait time on an event basis, 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(64) Indicates the last time the bucket was updated (the ending timestamp of the last wait falling into the bucket's duration)
CON_ID NUMBER The ID of the container to which the data pertains. 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


This view is available starting with Oracle Database 12c Release 1 (