Hive float datatype issue !!!

[#1]

Hello, i'm currently using CDH 5.2

I've a sample data like this :

0
18.6
36.1
53.7
86.5

but when i'm upload to hive with float type, i got this :

0.0

18.6000003815

36.0999984741

53.7000007629

86.5

I don't understand why 18.6 become 18.6000003815 , but 86.5 is still the same, every other variable is change except the .0 and .5 varible.

Can someone explain to me, really appreciate the help, thanks !

[#2 · Accepted solution]

This behavior is like any system with float representation, float bit representation does not allow exact representation of most values.  There is a lot of literature on the subject like  http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html

If you want exact values it's better to go with decimal, where you can specify scale and precision.

Thanks

Szehon