Given query displays per day the volume in MB of archived logs generated.

Given query displays per day the volume in MB of archived logs generated.

SELECT SUM_ARCH.DAY,

         SUM_ARCH.GENERATED_MB,
         SUM_ARCH_DEL.DELETED_MB,
         SUM_ARCH.GENERATED_MB - SUM_ARCH_DEL.DELETED_MB "REMAINING_MB"
    FROM (  SELECT TO_CHAR (COMPLETION_TIME, 'DD/MM/YYYY') DAY,
                   SUM (ROUND ( (blocks * block_size) / (1024 * 1024), 2))
                      GENERATED_MB
              FROM V$ARCHIVED_LOG
             WHERE ARCHIVED = 'YES'
          GROUP BY TO_CHAR (COMPLETION_TIME, 'DD/MM/YYYY')) SUM_ARCH,
         (  SELECT TO_CHAR (COMPLETION_TIME, 'DD/MM/YYYY') DAY,
                   SUM (ROUND ( (blocks * block_size) / (1024 * 1024), 2))
                      DELETED_MB
              FROM V$ARCHIVED_LOG
             WHERE ARCHIVED = 'YES' AND DELETED = 'YES'
          GROUP BY TO_CHAR (COMPLETION_TIME, 'DD/MM/YYYY')) SUM_ARCH_DEL
   WHERE SUM_ARCH.DAY = SUM_ARCH_DEL.DAY(+)
ORDER BY TO_DATE (DAY, 'DD/MM/YYYY');

 Below report will display the number of archived logs generated per hour per day:

 SELECT TO_CHAR (COMPLETION_TIME, 'DD/MM/YYYY') DAY,
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '00', 1, NULL))
            "00-01",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '01', 1, NULL))
            "01-02",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '02', 1, NULL))
            "02-03",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '03', 1, NULL))
            "03-04",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '04', 1, NULL))
            "04-05",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '05', 1, NULL))
            "05-06",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '06', 1, NULL))
            "06-07",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '07', 1, NULL))
            "07-08",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '08', 1, NULL))
            "08-09",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '09', 1, NULL))
            "09-10",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '10', 1, NULL))
            "10-11",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '11', 1, NULL))
            "11-12",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '12', 1, NULL))
            "12-13",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '13', 1, NULL))
            "13-14",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '14', 1, NULL))
            "14-15",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '15', 1, NULL))
            "15-16",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '16', 1, NULL))
            "16-17",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '17', 1, NULL))
            "17-18",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '18', 1, NULL))
            "18-19",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '19', 1, NULL))
            "19-20",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '20', 1, NULL))
            "20-21",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '21', 1, NULL))
            "21-22",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '22', 1, NULL))
            "22-23",
         SUM (DECODE (TO_CHAR (COMPLETION_TIME, 'HH24'), '23', 1, NULL))
            "23-00",
         COUNT (*) TOTAL
    FROM V$ARCHIVED_LOG
WHERE ARCHIVED='YES'
GROUP BY TO_CHAR (COMPLETION_TIME, 'DD/MM/YYYY')
ORDER BY TO_DATE (DAY, 'DD/MM/YYYY');


Find sessions generating lots of redo.
SELECT s.sid, s.serial#, s.username, s.program,
  i.block_changes
  FROM v$session s, v$sess_io i
  WHERE s.sid = i.sid
  ORDER BY 5 desc, 1, 2, 3, 4;

Below query can be used to find out which particular transactions are generating redo.
 select sql.sql_text sql_text, t.USED_UREC Records, t.USED_UBLK Blocks,
 (t.USED_UBLK*8192/1024) KBytes from v$transaction t,
 v$session s,
 v$sql sql
 where t.addr = s.taddr
 and s.sql_id = sql.sql_id
 and s.username ='&USERNAME';