Query to Generate aggregate on every 30 mins.
select to_char(first_time, ‘RRRRMMDDHH24’), COUNT (CASE WHEN TO_NUMBER(TO_CHAR(FIRST_time, ‘MI’)) 30 THEN 1 ELSE NULL END) COUNT2 FROM V$LOG_HISTORY GROUP BY to_char(first_time, ‘RRRRMMDDHH24’) order by 1 / TO_CHAR(FI COUNT1 COUNT2 ———- ———- ———- 2010020906 3 1 2010020907 3 1 2010020908 3 1 2010020909 3 1 2010020910 3 1 2010020911 3 1 2010020912 3 1 2010020913 3 1…