维度表更新方法 - 增量更新

维度表更新方法- 增量更新总结：



/******批量导入，从source表到stage target表，赋相应标识位:目的是找出新增加的和经过修改的记录******/
begin
    merge into emp_t t
    using (select * from emp_s) s
    on ( t.empid=s.empid
         and t.modify_time=s.modify_time)
    when matched then
      update set t.action_flag='0'
    when not matched then
      insert  (empid,empnm,deptnm,create_time,modify_time,action_flag)
        values (s.empid, s.empnm, s.deptnm, s.create_time, s.modify_time,'4' )
    ;
    commit;
end;
 
/******找出距离最近一次ETL时间以来，由源系统新增加的记录，赋标志位为2,维度表直接Insert*********/

begin
 update emp_t set action_flag='2' where create_time>(select nvl(max(create_time),to_date('01/01/2000','DD/MM/YYYY')) as createmaxtime from emp_t where action_flag='0' );
 commit;
end;


/****************找出数据仓库已经Load到的数据，但是在源系统经过修改的记录，改标志位为1，维度表需要更新或者生成新版本；
                  改原有记录的标志位为0，出错改标志位为5，0和5的记录不经过ETL到数据仓库*********/
begin
    
 merge into emp_t t
 using ( select empid,action_flag,empnm,deptnm,create_time,modify_time,rnk from(
          select empid,action_flag,empnm,deptnm,create_time,modify_time,rank() over(partition by empid order by modify_time desc)　as rnk
          from emp_t where empid in  ( select empid from emp_t where action_flag='4' )) s_tmp where rnk='1') s
 on (t.empid=s.empid
 and t.modify_time=s.modify_time)
 when matched then
    update set t.action_flag='1'
 when not matched then
     insert  (empid,empnm,deptnm,create_time,modify_time,action_flag)
        values (s.empid, s.empnm, s.deptnm, s.create_time, s.modify_time,'5' );
 commit;
    
 merge into emp_t t
 using ( select empid,action_flag,empnm,deptnm,create_time,modify_time,rnk from(
          select empid,action_flag,empnm,deptnm,create_time,modify_time,rank() over(partition by empid order by modify_time desc)　as rnk
          from emp_t where empid in  ( select empid from emp_t where action_flag='4' )) s_tmp where rnk='2') s
 on (t.empid=s.empid
 and t.modify_time=s.modify_time)
 when matched then
    update set t.action_flag='0'
 when not matched then
     insert  (empid,empnm,deptnm,create_time,modify_time,action_flag)
        values (s.empid, s.empnm, s.deptnm, s.create_time, s.modify_time,'5' );
 commit;
end;