Adding two decimal numbers Hive SQL

Question

I am trying to add two numbers using Hive SQL.

select 4.6 + 3.1 from <table> => 7.699999999999999

But,

select 4.7 +3.2 from <table>  => 7.9

I understand that rounding of result will give the expected output but the question is why this different behavior in first place?

I am using hive 2.11 (hive context) with Apache spark 1.6.2.

score 1 · Accepted Answer · edited May 23 '17 at 12:32

1

What you have observed is not Hive specific. Example:

Python 2.7.10 (default, Oct 23 2015, 19:19:21) 
>>> 4.7+3.2
7.9
>>> 4.6+3.1
7.699999999999999

It's related to how the double numbers are stored in memory in some languages (floating-point): https://en.wikipedia.org/wiki/Floating_point#Internal_representation

See also:

edited May 23 '17 at 12:32

Community

answered Sep 02 '16 at 17:01

Piotr Reszke

1 Answers1