Hello Listeners 😊,
Recently I've found three important views about *"v$waitclassmetric"*,
*"v$waitclassmetric_history"*, and *"dba_hist_waitclassmet_history"*.
Here're the corresponding links from oracle online docs:
*https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/V-WAITCLASSMETRIC.html*
<https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/V-WAITCLASSMETRIC.html>
*https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/V-WAITCLASSMETRIC_HISTORY.html#GUID-854BB495-19FC-4EB4-A81C-4D0EEA13B83C*
<https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/V-WAITCLASSMETRIC_HISTORY.html#GUID-854BB495-19FC-4EB4-A81C-4D0EEA13B83C>
*https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/DBA_HIST_WAITCLASSMET_HISTORY.html#GUID-A931DFBF-4023-41F0-A333-E56741DE589D*
<https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/DBA_HIST_WAITCLASSMET_HISTORY.html#GUID-A931DFBF-4023-41F0-A333-E56741DE589D>
Quoted the brief introduction for themselves:
9.131 V$WAITCLASSMETRIC
V$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.
9.132 V$WAITCLASSMETRIC_HISTORY
V$WAITCLASSMETRIC_HISTORY displays metric values of wait classes for all
intervals *in the last one hour*.
The columns for V$WAITCLASSMETRIC_HISTORY are the same as those for
V$WAITCLASSMETRIC.
DBA_HIST_WAITCLASSMET_HISTORY displays the *history of the wait event
class metric data* kept by the Workload Repository.
COUNT(*)
----------
13
16:43:29 SYS@ORACDB> select count(*) from v$waitclassmetric_history;
COUNT(*)
----------
793
16:43:33 SYS@ORACDB> select count(*) from dba_hist_waitclassmet_history;
COUNT(*)
----------
0