比较两个配置单元表之间的计数 [英] To compare count between two hive table

问题描述

我正在尝试计算两个表之间的比较.由于减号运算符在蜂巢中不起作用，因此不会发生.您能否提供一些简单的方法来进行两个表之间的计数比较.

I am trying to do count comparision between two table . As minus operator does not work in hive , it is not happening. Could you please give some simple way to do count comparision between two tables.

select  'Call Detail - Hive T1 to HDFS Staging - Data Compare',
case when cnt>0 then 'Fail' Else 'Pass' end
from
(select count(*) cnt from (
(select 
count(*) from students1 s1)-
(select count(*) from students2 s2)
) as tbl1
) as tbl2;

抛出错误:

失败:ParseException行81:0无法识别源中'(''(''select'附近的输入

FAILED: ParseException line 81:0 cannot recognize input near '(' '(' 'select' in from source

推荐答案

如果没有按列分组，请使用cross join.在这种情况下，它将产生包含两个计数的一行:

Use cross join if you have no group by columns. In this case it will produce one row with both counts:

select s.cnt-s1.cnt diff, case when abs(s.cnt-s1.cnt) > 0 then 'Fail' Else 'Pass' end result
from
(select count(*) cnt  from students1 s1) s
cross join
(select count(*) cnt from students2 s2) s1

如果要添加一些按列分组以比较更详细的谷物，请在按列分组上使用FULL JOIN:

If you will add some group by columns to compare on more detailed grain, then use FULL JOIN on group by columns:

select s.col1 s_col1, s1.col1 s1_col1, s.cnt-s1.cnt diff, case when abs(s.cnt-s1.cnt) > 0 then 'Fail' Else 'Pass' end result
from
(select count(*) cnt, col1  from students1 s1 group by col1) s
full join
(select count(*) cnt, col1 from students2 s2 group by col1) s1 
on s.col1 = s1.col1

此查询将返回已计算差异的联接行，并且两个表中都不联接行.

This query will return joined rows with difference calculated and also not joined rows from both tables.

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