V$WAITCLASSMETRIC

Oracle 11gR1

V$WAITCLASSMETRIC displays metric values of wait classes for the most recent 60-second interval. A history of the last one hour will be kept in the system.

Column	Datatype	Description
BEGIN_TIME	DATE	Begin time of the interval
END_TIME	DATE	End time of the interval
INTSIZE_CSEC	NUMBER	Interval size (in hundredths of a second)
WAIT_CLASS#	NUMBER	Number of the class of the wait event
WAIT_CLASS_ID	NUMBER	Identifier of the class of the wait event
AVERAGE_WAITER_COUNT	NUMBER	Average waiter count
DBTIME_IN_WAIT	NUMBER	Percent of database time spent in the wait
TIME_WAITED	NUMBER	Time waited during the interval (in microseconds)
WAIT_COUNT	NUMBER	Number of times waited

Note:

1.

select * from V$WAITCLASSMETRIC;

BEGIN_TIME	END_TIME	INTSIZE_ CSEC	WAIT_ CLASS#	WAIT_ CLASS_ID	AVERAGE_ WAITER_ COUNT	DBTIME_ IN_ WAIT	TIME_ WAITED	WAIT_ COUNT
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	0	1893977003	3.10835705911908E-5	0.00090602106599539	0.1856	15
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	1	4217450380	0.00354054597219896	0.10319950941693	21.1406	96
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	2	3290255840	0	0	0	0
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	3	4166625743	0	0	0	0
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	4	3875070507	0.000211137162954279	0.00615420666972192	1.2607	8
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	5	3386400367	0.00162440127281862	0.047347899382592	9.6993	93
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	6	2723168908	512.018350041869	0	3057261.5681	40814
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	7	2000153315	0.156435203483504	4.55975896988802	934.0746	291137
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	8	1740759767	1.33239013565567	38.8363855267841	7955.7015	24609
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	9	4108307767	0.00865977223245687	0.252414247144163	51.7075	866
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	10	2396326234	0	0	0	0
2008-08-28 11:45:51 AM	2008-08-28 11:46:51 AM	5971	11	3871361733	0	0	0	0

2. v$waitclassmetric is a rollup of v$eventmetric. It is apparent that this is one of the ways Oracle is attempting to make database performance tuning easier, particularly for the less-experienced DBA. For the more experienced DBA, the wait classes might provide a quick health check; however, the resolution of a specific problem may be most effective with more granular detail. By querying v$waitclassmetric, the biggest area of concern can be quickly identified. The DBA might be interested in seeing what wait classes 6, 7 and 9 represent. Querying the v$system_wait_class view is one way to identify what the wait classes represent. This view has a historical rollup for the entire time the instance has been up, but it also provides a way to change wait_class# into the name of that class.

Oracle dynamic performance views