sqoop에서 mapper를 2이상으로 설정하기 위한 split-by컬럼을 찾을때 유용하게 활용할 수 있는 쿼리

(abctable에서 part_ym='201908'인 데이터를 가지고 test_col이라는 컬럼의 값을 이용하여 10등분하고 그 개수를 확인하는 impala sql임, -1은 마지막 값에 속하는 개수를 의미함)

select tt, count(*) from {
   select case when bb.lapse1 <= cast(substr(aa.test_col, 5,4) as int) and case(substr(aa.test_col, 5,4) as int) < bb.lapse2 then t
                  when t=10 and bb.lapse2 = cast(substr(aa.test_col, 5,4) as int) then -1
            end tt
   from 
    (select * from dw.abctable where part_ym='201908' aa,
    (select min_val, max_vl, t, max_val*((t-1)/10) as lapse1, max_val*((t+0)/10) as lapse2 from
          (select min(cast(substr(test_col, 5,4) as int)) as min_val, max(cast(substr(test_col, 5,4) as int)) as max_val from dw.abctable where part_ym= '201908') a, 
          (select cast(t as int) as t from copy_t where t in ('01','02','03','04','05','06','07','08','09','10')) b
    ) bb
} kk
where kk.tt is not null
group by kk.tt
order by 1;