adjust the default interval for statistics collection
  修改方法：em 或
  BEGIN
  DBMS_SCHEDULER.DISABLE(
  name=>'SYS.WEEKNIGHT_WINDOW',
  force=>TRUE);
  END;

  BEGIN
  DBMS_SCHEDULER.SET_ATTRIBUTE(
  name=>'SYS.WEEKNIGHT_WINDOW',
  attribute=>'REPEAT_INTERVAL',
  value=>'FREQ=MINUTELY;INTERVAL=2');
  END;

  BEGIN
  DBMS_SCHEDULER.ENABLE(
  name=>'SYS.WEEKNIGHT_WINDOW');
  END;
                -----------------------------------------------------------------------------------------------------------------------
  oracle安装后默认配置了自动采集统计信息的JOB
  查看 dba_scheduler_jobs
  OWNER SYS
  JOB_NAME GATHER_STATS_JOB
  JOB_CREATOR SYS
  PROGRAM_OWNER SYS
  PROGRAM_NAME GATHER_STATS_PROG  
  SCHEDULE_OWNER SYS
  SCHEDULE_NAME MAINTENANCE_WINDOW_GROUP
  SCHEDULE_TYPE WINDOW_GROUP 
  JOB_CLASS AUTO_TASKS_JOB_CLASS
  AUTO_DROP FALSE
  RESTARTABLE TRUE
  STATE SCHEDULED
  JOB_PRIORITY 3
  RUN_COUNT 7 
  FAILURE_COUNT 0
  RETRY_COUNT 0
  LAST_START_DATE 07-7月 -10 04.29.38.423000 下午 +08:00
  LAST_RUN_DURATION +000000000 00:00:00.953000 
  LOGGING_LEVEL RUNS
  STOP_ON_WINDOW_CLOSE TRUE
  INSTANCE_STICKINESS TRUE
  JOB_WEIGHT 1
  NLS_ENV NLS_LANGUAGE='AMERICAN' NLS_TERRITORY='AMERICA' NLS_CURRENCY='$' NLS_ISO_CURRENCY='AMERICA' NLS_NUMERIC_CHARACTERS='.,' NLS_CALENDAR='GREGORIAN' NLS_DATE_FORMAT='DD-MON-RR' NLS_DATE_LANGUAGE='AMERICAN' NLS_SORT='BINARY' NLS_TIME_FORMAT='HH.MI.SSXFF AM' NLS_TIMESTAMP_FORMAT='DD-MON-RR HH.MI.SSXFF AM' NLS_TIME_TZ_FORMAT='HH.MI.SSXFF AM TZR' NLS_TIMESTAMP_TZ_FORMAT='DD-MON-RR HH.MI.SSXFF AM TZR' NLS_DUAL_CURRENCY='$' NLS_COMP='BINARY' NLS_LENGTH_SEMANTICS='BYTE' NLS_NCHAR_CONV_EXCP='FALSE' 
  COMMENTS Oracle defined automatic optimizer statistics collection job

  拆解出来
  (1)how。。
  program：GATHER_STATS_PROG
  OWNER SYS
  PROGRAM_NAME GATHER_STATS_PROG
  PROGRAM_TYPE STORED_PROCEDURE
  PROGRAM_ACTION dbms_stats.gather_database_stats_job_proc
  NUMBER_OF_ARGUMENTS 0
  ENABLED TRUE
  DETACHED FALSE
  COMMENTS Oracle defined automatic optimizer statistics collection program
  (2)when..
  预定义窗口
  WEEKNIGHT_WINDOW  WEEKEND_WINDOW
顺便复习：scheduler window

SQL> desc dbms_scheduler.create_window
Parameter       Type                     Mode Default?
--------------- ------------------------ ---- --------
WINDOW_NAME     VARCHAR2                 IN           
RESOURCE_PLAN   VARCHAR2                 IN           
SCHEDULE_NAME   VARCHAR2                 IN           
DURATION        INTERVAL DAY TO SECOND   IN           
WINDOW_PRIORITY VARCHAR2                 IN   Y       
COMMENTS        VARCHAR2                 IN   Y       
WINDOW_NAME     VARCHAR2                 IN           
RESOURCE_PLAN   VARCHAR2                 IN           
START_DATE      TIMESTAMP WITH TIME ZONE IN   Y       
REPEAT_INTERVAL VARCHAR2                 IN           
END_DATE        TIMESTAMP WITH TIME ZONE IN   Y       
DURATION        INTERVAL DAY TO SECOND   IN           
WINDOW_PRIORITY VARCHAR2                 IN   Y       
COMMENTS        VARCHAR2                 IN   Y  
借用em重温一个参数REPEAT_INTERVAL  从秒到年。。
 
'FREQ=SECONDLY;INTERVAL=10'
 
'FREQ=MINUTELY;INTERVAL=20'
。。。。。。。。。。
'FREQ=HOURLY;INTERVAL=20'
 
'FREQ=DAILY;INTERVAL=5;BYHOUR=20;BYMINUTE=3;BYSECOND=20'
 
'FREQ=WEEKLY;INTERVAL=5;BYDAY=MON,TUE,WED,THU,FRI,SAT,SUN;BYHOUR=22;BYMINUTE=3;BYSECOND=20'
 
'FREQ=MONTHLY;INTERVAL=3;BYMONTHDAY=1,8,15,22,29;BYHOUR=18;BYMINUTE=3;BYSECOND=20'
 
'FREQ=YEARLY;INTERVAL=2;BYYEARDAY=6,-113;BYHOUR=15;BYMINUTE=3;BYSECOND=20'