I would like to know if it is possible to know the number of days that Oracle keeps the data in the table USER_SCHEDULER_JOB_RUN_DETAILS
and also if it is possible to change it.
It is depends from parameter of job_class , but if parameter is not set default value is 30 days (in oracle 11.2)
select job_class_name,log_history from dba_SCHEDULER_job_classes where job_class_name ='DEFAULT_JOB_CLASS';
to change the parameter.
BEGIN
DBMS_SCHEDULER.set_attribute (NAME => 'SYS.DEFAULT_JOB_CLASS',
ATTRIBUTE => 'log_history',
VALUE => 300 -- <-- in days
);
END;