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Same query, same data, different results between SQL Server and Impala

Same query, same data, different results between SQL Server and Impala

Explorer

I am running the following query on the same data (same tables, and the same number of records on those tables), but it gives a different result on Impala than what I get on SQL Server.

 

The following on Impala:

Capture.JPG

and this is on SQL Server:

Capture2.JPG

 

I am very sure that the data is the same in everything ... actually, I have imported the data from SQL Server through Sqoop and after that made sure that the number of records is the same in the source and destination .... yet I don't know why I'm getting a defferent result here and there ?!!!

 

3 REPLIES 3

Re: Same query, same data, different results between SQL Server and Impala

Expert Contributor

Hi @anis447 

 

Can you bring us this queries results in SQL server and Impala:

Select avg(tagno) from tag;
Select avg(tagno) from has_tag;
Select count(*) from tag where tagno is null;
Select count(*) from has_tag where tagno is null;

Also try to add this on Impala query, and let us know if there is any change:

...
Inner join has_tags hit on (s.tagno = hit.tagno and s.categorycode = hit.categorycode)
...

Good luck.

Re: Same query, same data, different results between SQL Server and Impala

Master Collaborator

It'd be helpful to post your impala version too.

 

It seems unlikely that either SQL engine would return incorrect results on a straightforward query like this.

 

I'd suggest looking at a subset of the data and breaking down the query until you can see where the different lies, e.g.

 

select *
FROM tag s
  INNER JOIN  has_tags ht on S.TagNo = HT.TagNo and S.CategoryCode =  HT.CategoryCode
WHERE ht.categorycode = 'SYS'

Re: Same query, same data, different results between SQL Server and Impala

Master Collaborator

The output of "explain <query>" is often helpful too.