Online Redo Log Switch Frequency

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 SELECT TRUNC (first_time) "Date", inst_id, TO_CHAR (first_time, 'Dy') "Day",  
  COUNT (1) "Total",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '00', 1, 0)) "h0",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '01', 1, 0)) "h1",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '02', 1, 0)) "h2",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '03', 1, 0)) "h3",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '04', 1, 0)) "h4",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '05', 1, 0)) "h5",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '06', 1, 0)) "h6",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '07', 1, 0)) "h7",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '08', 1, 0)) "h8",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '09', 1, 0)) "h9",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '10', 1, 0)) "h10",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '11', 1, 0)) "h11",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '12', 1, 0)) "h12",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '13', 1, 0)) "h13",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '14', 1, 0)) "h14",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '15', 1, 0)) "h15",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '16', 1, 0)) "h16",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '17', 1, 0)) "h17",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '18', 1, 0)) "h18",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '19', 1, 0)) "h19",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '20', 1, 0)) "h20",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '21', 1, 0)) "h21",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '22', 1, 0)) "h22",  
  SUM (DECODE (TO_CHAR (first_time, 'hh24'), '23', 1, 0)) "h23",  
  ROUND (COUNT (1) / 24, 2) "Avg"  
 FROM gv$log_history  
 WHERE thread# = inst_id  
 AND first_time > sysdate -7  
 GROUP BY TRUNC (first_time), inst_id, TO_CHAR (first_time, 'Dy')  
 ORDER BY 1,2;