行業客戶 12c 何時自動收集統計信息？

每個行業都有自己的特點，比如金融行業，每天晚上10點左右會跑批，而自動收集統計信息默認週一到週五晚上10點，持續4個小時收集統計信息，週六週日每天6點，持續20個小時收集統計信息。顯然我們應該設計一個更加合適的時間點來收集統計信息。

這裏演示每天凌晨1點，持續5個小時收集統計信息的方法。

1.查看版本
SQL> select * from v$version;

BANNER                                                                               CON_ID
-------------------------------------------------------------------------------- ----------
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production              0
PL/SQL Release 12.1.0.2.0 - Production                                                    0
CORE    12.1.0.2.0      Production                                                        0
TNS for Linux: Version 12.1.0.2.0 - Production                                            0
NLSRTL Version 12.1.0.2.0 - Production                                                    0

SQL> 

--默認值如下
set lines 200
col WINDOW_NAME for a20
col REPEAT_INTERVAL for a60 
col DURATION  for a20
SELECT w.window_name,
               w.repeat_interval,
               w.duration,
               w.enabled
          FROM dba_autotask_window_clients c, dba_scheduler_windows w
         WHERE c.window_name = w.window_name AND c.optimizer_stats = 'ENABLED';

SQL> set lines 200
SQL> col WINDOW_NAME for a20
SQL> col REPEAT_INTERVAL for a60 
SQL> col DURATION  for a20
SQL> SELECT w.window_name,
  2                 w.repeat_interval,
  3                 w.duration,
  4                 w.enabled
  5            FROM dba_autotask_window_clients c, dba_scheduler_windows w
  6           WHERE c.window_name = w.window_name AND c.optimizer_stats = 'ENABLED';

WINDOW_NAME          REPEAT_INTERVAL                                              DURATION             ENABL
-------------------- ------------------------------------------------------------ -------------------- -----
TUESDAY_WINDOW       freq=daily;byday=TUE;byhour=22;byminute=0; bysecond=0        +000 04:00:00        TRUE
WEDNESDAY_WINDOW     freq=daily;byday=WED;byhour=22;byminute=0; bysecond=0        +000 04:00:00        TRUE
THURSDAY_WINDOW      freq=daily;byday=THU;byhour=22;byminute=0; bysecond=0        +000 04:00:00        TRUE
FRIDAY_WINDOW        FREQ=daily;BYDAY=FRI;BYHOUR=22;BYMINUTE=30;BYSECOND=0        +000 04:00:00        TRUE
SATURDAY_WINDOW      freq=daily;byday=SAT;byhour=6;byminute=0; bysecond=0         +000 20:00:00        TRUE
SUNDAY_WINDOW        freq=daily;byday=SUN;byhour=6;byminute=0; bysecond=0         +000 20:00:00        TRUE

6 rows selected.

--修改自動收集統計信息每天凌晨一點，持續5個小時。
    --MONDAY
    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE (
            name        => '"SYS"."MONDAY_WINDOW"',
            attribute   => 'REPEAT_INTERVAL',
            VALUE       => 'FREQ=daily;BYDAY=MON;BYHOUR=1;BYMINUTE=0;BYSECOND=0');
        END;
    /

    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE(
        name => '"SYS"."MONDAY_WINDOW"',
        attribute => 'DURATION',
        value => numtodsinterval(300,'minute'));
     END;  
     /
    --TUESDAY
    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE (
            name        => '"SYS"."TUESDAY_WINDOW"',
            attribute   => 'REPEAT_INTERVAL',
            VALUE       => 'FREQ=daily;BYDAY=TUE;BYHOUR=1;BYMINUTE=0;BYSECOND=0');
        END;
    /

    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE(
        name => '"SYS"."TUESDAY_WINDOW"',
        attribute => 'DURATION',
        value => numtodsinterval(300,'minute'));
     END;  
     /

     --WEDNESDAY
     BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE (
            name        => '"SYS"."WEDNESDAY_WINDOW"',
            attribute   => 'REPEAT_INTERVAL',
            VALUE       => 'FREQ=daily;BYDAY=WED;BYHOUR=1;BYMINUTE=0;BYSECOND=0');
        END;
    /

    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE(
        name => '"SYS"."WEDNESDAY_WINDOW"',
        attribute => 'DURATION',
        value => numtodsinterval(300,'minute'));
     END;  
     /

     --THURSDAY
      BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE (
            name        => '"SYS"."THURSDAY_WINDOW"',
            attribute   => 'REPEAT_INTERVAL',
            VALUE       => 'FREQ=daily;BYDAY=THU;BYHOUR=1;BYMINUTE=0;BYSECOND=0');
        END;
    /

    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE(
        name => '"SYS"."THURSDAY_WINDOW"',
        attribute => 'DURATION',
        value => numtodsinterval(300,'minute'));
     END;  
     /

    --FRIDAY
     BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE (
            name        => '"SYS"."FRIDAY_WINDOW"',
            attribute   => 'REPEAT_INTERVAL',
            VALUE       => 'FREQ=daily;BYDAY=FRI;BYHOUR=1;BYMINUTE=0;BYSECOND=0');
        END;
    /

    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE(
        name => '"SYS"."FRIDAY_WINDOW"',
        attribute => 'DURATION',
        value => numtodsinterval(300,'minute'));
     END;  
     /
    --SATURDAY
    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE (
            name        => '"SYS"."SATURDAY_WINDOW"',
            attribute   => 'REPEAT_INTERVAL',
            VALUE       => 'FREQ=daily;BYDAY=SAT;BYHOUR=1;BYMINUTE=0;BYSECOND=0');
        END;
    /

    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE(
        name => '"SYS"."SATURDAY_WINDOW"',
        attribute => 'DURATION',
        value => numtodsinterval(300,'minute'));
     END;  
     /

    --SUNDAY
    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE (
            name        => '"SYS"."SUNDAY_WINDOW"',
            attribute   => 'REPEAT_INTERVAL',
            VALUE       => 'FREQ=daily;BYDAY=SUN;BYHOUR=1;BYMINUTE=0;BYSECOND=0');
        END;
    /

    BEGIN
        DBMS_SCHEDULER.SET_ATTRIBUTE(
        name => '"SYS"."SUNDAY_WINDOW"',
        attribute => 'DURATION',
        value => numtodsinterval(300,'minute'));
     END;  
     /

SQL> --驗證是否變更
SQL> set lines 200
SQL> col WINDOW_NAME for a20
SQL> col REPEAT_INTERVAL for a60 
SQL> col DURATION  for a20
SQL> SELECT w.window_name,
  2                 w.repeat_interval,
  3                 w.duration,
  4                 w.enabled
  5            FROM dba_autotask_window_clients c, dba_scheduler_windows w
  6           WHERE c.window_name = w.window_name AND c.optimizer_stats = 'ENABLED';

WINDOW_NAME          REPEAT_INTERVAL                                              DURATION             ENABL
-------------------- ------------------------------------------------------------ -------------------- -----
MONDAY_WINDOW        FREQ=daily;BYDAY=MON;BYHOUR=1;BYMINUTE=0;BYSECOND=0          +000 05:00:00        TRUE
TUESDAY_WINDOW       FREQ=daily;BYDAY=TUE;BYHOUR=1;BYMINUTE=0;BYSECOND=0          +000 05:00:00        TRUE
WEDNESDAY_WINDOW     FREQ=daily;BYDAY=WED;BYHOUR=1;BYMINUTE=0;BYSECOND=0          +000 05:00:00        TRUE
THURSDAY_WINDOW      FREQ=daily;BYDAY=THU;BYHOUR=1;BYMINUTE=0;BYSECOND=0          +000 05:00:00        TRUE
FRIDAY_WINDOW        FREQ=daily;BYDAY=FRI;BYHOUR=1;BYMINUTE=0;BYSECOND=0          +000 05:00:00        TRUE
SATURDAY_WINDOW      FREQ=daily;BYDAY=SAT;BYHOUR=1;BYMINUTE=0;BYSECOND=0          +000 05:00:00        TRUE
SUNDAY_WINDOW        FREQ=daily;BYDAY=SUN;BYHOUR=1;BYMINUTE=0;BYSECOND=0          +000 05:00:00        TRUE

7 rows selected.

SQL> 

看到太多的客戶都是默認值，當然對非7*24小時的系統也沒有太大影響。但是，某些7X24小時的業務系統，我們需要做更多的優化調整，然後持續跟蹤，不斷優化。保證業務的連續性。不管大家有沒有設置，都需要大家知道這裏可能會引起性能問題的一個點，我們必須考慮到。