Problems with Floating-Point Comparisons

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Having run across the problems with float comparisons and having read =
http://dev.mysql.com/doc/mysql/en/Problems_with_float.html
I consider the problem with floating point comparisons to be a bug in =
mysql.

When performing comparisons of floating point numbers, shouldn't mysql =
implicitly round the floating point number to the level of percision =
defined. For example, if a table column is defined as float(4,2), one =
would expect that the stored value would be automatically rounded to 2 =
decimal places before evaluating the comparison.

The problem is trival to work around, but a nuisance and it should be =
fixed.
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Re: Problems with Floating-Point Comparisons

Hi!

On Dec 13, J.T. Moore wrote:
> Having run across the problems with float comparisons and having read
> http://dev.mysql.com/doc/mysql/en/Problems_with_float.html
> I consider the problem with floating point comparisons to be a bug in mysql.
>
> When performing comparisons of floating point numbers, shouldn't mysql
> implicitly round the floating point number to the level of percision
> defined. For example, if a table column is defined as float(4,2), one
> would expect that the stored value would be automatically rounded to 2
> decimal places before evaluating the comparison.

Not a bad idea.

> The problem is trival to work around, but a nuisance and it should be fixed.

Even though the idea itself makes sense, it cannot be done before 5.0 -
as it would definitely change the documented behaviour of a stable
version. We cannot do it.

As for 5.0 - it will close the whole issue by suporting exact numeric
types.

Regards,
Sergei

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__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Sergei Golubchik
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, Senior Software Developer
/_/ /_/\_, /___/\___\_\___/ Osnabrueck, Germany
<___/ www.mysql.com

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