Johnny Zhang created HIVE-3715:
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             Summary: float and double miss calculation is inaccurate in Hive
                 Key: HIVE-3715
                 URL: https://issues.apache.org/jira/browse/HIVE-3715
             Project: Hive
          Issue Type: Bug
          Components: SQL
    Affects Versions: 0.10.0
            Reporter: Johnny Zhang
            Assignee: Johnny Zhang


I found this during debug the e2e test failures. I found Hive miss calculate 
the float and double value. Take float calculation as an example:

hive> select f from all100k limit 1;
48308.98
hive> select f/10 from all100k limit 1;
4830.898046875   <--added 04875 in the end
hive> select f*1.01 from all100k limit 1;
48792.0702734375  <--should be 48792.0698

It might be essentially the same problem as 
http://effbot.org/pyfaq/why-are-floating-point-calculations-so-inaccurate.htm. 
But since e2e test compare the results with mysql and seems mysql does it 
right, so it is worthy fixing it in Hive.

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