【DB笔试面试480】 RAC中如何指定JOB的运行实例？

小麦苗DBA宝典

发布于 2019-09-29 15:14:46

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发布于 2019-09-29 15:14:46

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题目部分

RAC中如何指定JOB的运行实例？

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答案部分

在RAC中，可以让JOB在某个指定的实例上运行。对于DBMS_JOB和DBMS_SCHEDULER来说，它们的指定方法不同：

（1）在DBMS_JOB下，在执行SYS.DBMS_JOB.SUBMIT包创建JOB的时候，可以指定INSTANCE参数，该参数指定了JOB运行的实例。在RAC环境中，采用DBMS_JOB包可以指定JOB运行时候的实例。

示例代码如下所示，该例子展示了获取RAC数据库的IP地址并记录到临时表T_IPADDRESS_LHR中，例子很经典，希望读者可以理解。

1）创建临时表用于记录RAC数据库的IP地址

DROP TABLE T_IPADDRESS_LHR;
CREATE TABLE T_IPADDRESS_LHR(INST_ID NUMBER, HOST_NAME VARCHAR2(255), HOST_IP  VARCHAR2(255) );

2）创建视图VH_IPADDRESS_LHR用于从V$DIAG_ALERT_EXT中获取IP地址

CREATE OR REPLACE VIEW VH_IPADDRESS_LHR AS  
SELECT A.HOST_ID || ': ' || A.HOST_ADDRESS HOST_IP1,
       A.HOST_ADDRESS HOST_IP2,
  A.HOST_ID HOST_NAME2
        FROM V$DIAG_ALERT_EXT A
       WHERE A.COMPONENT_ID = 'RDBMS'
         AND UPPER(A.FILENAME) =
             (SELECT UPPER(SUBSTR(D.VALUE, 1, (LENGTH(D.VALUE) - 5)) ||
                           'ALERT' || SUBSTR(D.VALUE, -6, 1) || 'LOG.XML')
                FROM V$PARAMETER D
               WHERE D.NAME = 'BACKGROUND_DUMP_DEST')
         AND A.INDX =
             (SELECT MAX(B.INDX)
                FROM V$DIAG_ALERT_EXT B
               WHERE B.COMPONENT_ID = 'RDBMS'
                 AND UPPER(B.FILENAME) =
                     (SELECT UPPER(SUBSTR(D.VALUE, 1, (LENGTH(D.VALUE) - 5)) ||
                                   'ALERT' || SUBSTR(D.VALUE, -6, 1) ||
                                   'LOG.XML')
                        FROM V$PARAMETER D
                       WHERE D.NAME = 'BACKGROUND_DUMP_DEST'));
/

3）创建存储过程用于在指定的实例上运行程序，首先从函数UTL_INADDR.GET_HOST_ADDRESS中获取，若是系统没有该包，则从视图VH_IPADDRESS_LHR中获取IP地址

CREATE OR REPLACE PROCEDURE PH_IP_LHR AS
  V_SQL VARCHAR2(4000);
BEGIN
  INSERT INTO T_IPADDRESS_LHR
    (INST_ID, HOST_NAME)
    SELECT V.INSTANCE_NUMBER, V.HOST_NAME FROM V$INSTANCE V;
  COMMIT;
  V_SQL := 'UPDATE T_IPADDRESS_LHR T
     SET T.HOST_IP = UTL_INADDR.GET_HOST_ADDRESS
   WHERE T.INST_ID = USERENV(''INSTANCE'')';
  EXECUTE IMMEDIATE V_SQL;
  COMMIT;
EXCEPTION
  WHEN OTHERS THEN
    V_SQL := 'UPDATE T_IPADDRESS_LHR T
       SET T.HOST_IP =
           (SELECT V.HOST_IP2 FROM VH_IPADDRESS_LHR V)
     WHERE T.INST_ID = USERENV(''INSTANCE'')';
    EXECUTE IMMEDIATE V_SQL;
    COMMIT;
END PH_IP_LHR;
/

4）创建JOB来获取IP地址

DECLARE
  X NUMBER;
BEGIN
  FOR CUR IN (SELECT B.JOB
                FROM DBA_JOBS B
               WHERE B.WHAT = 'PH_IP_LHR;') LOOP
    SYS.DBMS_IJOB.REMOVE(CUR.JOB);
    COMMIT;
  END LOOP;
  FOR CUR IN (SELECT B.INST_ID FROM GV$INSTANCE B) LOOP
    SYS.DBMS_JOB.SUBMIT(JOB       => X,
                        WHAT      => 'PH_IP_LHR;',
                        NEXT_DATE => SYSDATE+CUR.INST_ID/8640,
                        INTERVAL  => 'NULL',
                        NO_PARSE  => FALSE,
                        INSTANCE  => CUR.INST_ID);
    COMMIT;
  END LOOP;
END;
/

（2）DBMS_SCHEDULER下指定实例运行JOB稍微有点复杂，首先创建SERVICE，再创建JOB_CLASS，最后创建JOB才可以，具体过程可以参考如下案例的代码。

该例子和上面的DBMS_JOB例子一样展示了获取集群数据库的IP地址并记录到临时表T_IPADDRESS_LHR中，例子的前3步和上面的例子一样，不再赘述，接下来就是创建SERVICE和JOB_CLASS，最后是创建JOB的过程。

BEGIN
  FOR CUR IN (SELECT V.INST_ID,
                     V.INSTANCE_NAME,
                     'INST_LHR_' || V.INST_ID SERVICE_NAME,
                     'LHR_RAC' || V.INST_ID || '_JOB_CLASS' JOB_CLASS_NAME,
                     'RAC_LHR_' || V.INST_ID JOB_NAME
                FROM GV$INSTANCE V) LOOP
    BEGIN
      DBMS_SERVICE.STOP_SERVICE(SERVICE_NAME  => CUR.SERVICE_NAME,
                                INSTANCE_NAME => CUR.INSTANCE_NAME);
      DBMS_SERVICE.DELETE_SERVICE(SERVICE_NAME => CUR.SERVICE_NAME);
    EXCEPTION
      WHEN OTHERS THEN
        NULL;
    END;
    BEGIN
      DBMS_SCHEDULER.DROP_JOB_CLASS(JOB_CLASS_NAME => CUR.JOB_CLASS_NAME,
                                    FORCE          => TRUE);
    EXCEPTION
      WHEN OTHERS THEN
        NULL;
    END;
    BEGIN
      DBMS_SCHEDULER.DROP_JOB(JOB_NAME => CUR.JOB_NAME, FORCE => TRUE);
    EXCEPTION
      WHEN OTHERS THEN
        NULL;
    END;
  END LOOP;
  FOR CUR IN (SELECT V.INST_ID,
                     V.INSTANCE_NAME,
                     'INST_LHR_' || V.INST_ID SERVICE_NAME,
                     'LHR_RAC' || V.INST_ID || '_JOB_CLASS' JOB_CLASS_NAME,
                     'RAC_LHR_' || V.INST_ID JOB_NAME
                FROM GV$INSTANCE V) LOOP
    DBMS_SERVICE.CREATE_SERVICE(SERVICE_NAME => CUR.SERVICE_NAME,
                                NETWORK_NAME => CUR.SERVICE_NAME);
    DBMS_SERVICE.START_SERVICE(SERVICE_NAME  => CUR.SERVICE_NAME,
                               INSTANCE_NAME => CUR.INSTANCE_NAME);
    DBMS_SCHEDULER.CREATE_JOB_CLASS(JOB_CLASS_NAME => CUR.JOB_CLASS_NAME,
                                    SERVICE        => CUR.SERVICE_NAME);
    DBMS_SCHEDULER.CREATE_JOB(JOB_NAME    => 'RAC_LHR_' || CUR.INST_ID,
                              JOB_TYPE        => 'STORED_PROCEDURE',
                              JOB_ACTION      => 'PH_IP_LHR',
                              REPEAT_INTERVAL => NULL, --'FREQ=MINUTELY;INTERVAL=1'
                              JOB_CLASS       => CUR.JOB_CLASS_NAME,
                              END_DATE        => NULL,
                              ENABLED         => TRUE);
  END LOOP;
END;
/

& 说明：

有关具体的操作过程可以参考我的BLOG：http://blog.itpub.net/26736162/viewspace-2072635/