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#1 (**permalink**) 04-10-2008, 10:58 AM

The following bug has been logged online:

Bug reference: 3467
Logged by: Alex
Email address: AVShutko@mail.khstu.ru
PostgreSQL version: 8.2.4
Operating system: FreeBSD 6.2-RELEASE-p4
Description: Sum strange behaviour
Details:

I have a database with some float numbers (all of them are 2 digits
presision). When I do select sum() I get this: 96.3100000000001

Here are the numbers:

4.29
4.29
0.29
14.3
1.43
14.3
1.43
1.43
7.15
2.94
0.14
5.56
1.43
0.29
0.59
1.43
1.43
1.43
1.43
21.45
1.43
0.14
2.15
1.43
1.43
1.43
1.43
0.59
0.22
1.43
1.18

Is this bug or future ?

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#2 (**permalink**) 04-10-2008, 10:58 AM

Alex wrote:
> I have a database with some float numbers (all of them are 2 digits
> presision). When I do select sum() I get this: 96.3100000000001
> ...
> Is this bug or future ?

A feature. Floating point numbers can't generally represent a decimal
number exactly, so you get some rounding errors. Usually the errors are
small enough that they don't show up, but sometimes they do, like in
this example. I would recommend using NUMERIC instead of floats for
anything where the input data is in decimal format.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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BUG #3467: Sum strange behaviour