为什么需要统计
1.可以预估主机或共享存储目录空间是否满足业务的需求
2.便于统计/概览哪个时间段应用进行了大批量的操作，

SELECT 
           SUBSTR(TO_CHAR(T.RECORD_TIME, 'yyyy-mm-dd'), 1, 10) as Day,
           TO_CHAR(T.RECORD_TIME, 'Dy') as weekday,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '00',
                      1,
                      0)) H00,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '01',
                      1,
                      0)) H01,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '02',
                      1,
                      0)) H02,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '03',
                      1,
                      0)) H03,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '04',
                      1,
                      0)) H04,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '05',
                      1,
                      0)) H05,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '06',
                      1,
                      0)) H06,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '07',
                      1,
                      0)) H07,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '08',
                      1,
                      0)) H08,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '09',
                      1,
                      0)) H09,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '10',
                      1,
                      0)) H10,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '11',
                      1,
                      0)) H11,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '12',
                      1,
                      0)) H12,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '13',
                      1,
                      0)) H13,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '14',
                      1,
                      0)) H14,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '15',
                      1,
                      0)) H15,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '16',
                      1,
                      0)) H16,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '17',
                      1,
                      0)) H17,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '18',
                      1,
                      0)) H18,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '19',
                      1,
                      0)) H19,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '20',
                      1,
                      0)) H20,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '21',
                      1,
                      0)) H21,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '22',
                      1,
                      0)) H22,
           SUM(DECODE(SUBSTR(TO_CHAR(T.RECORD_TIME, 'MM/DD/RR HH24:MI:SS'),
                             10,
                             2),
                      '23',
                      1,
                      0)) H23,
           COUNT(*) TOTAL
    FROM   V$RLOG_HISTORY T
     group  by 
              SUBSTR(TO_CHAR(T.RECORD_TIME, 'yyyy-mm-dd'), 1, 10),
              TO_CHAR(T.RECORD_TIME, 'Dy')
    order  by 2, 1;