OSDir


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Implicit Casts for Arithmetic Operators


Hi,

I would like to try to clarify things a bit to help people to understand
the true complexity of the problem.

The *float *and *double *types are inexact numeric types. Not only at the
operation level.

If you insert 676543.21 in a *float* column and then read it, you will
realize that the value has been truncated to 676543.2.

If you want accuracy the only way is to avoid those inexact types.
Using *decimals
*during operations will mitigate the problem but will not remove it.


I do not recall PostgreSQL behaving has described. If I am not mistaken in
PostgreSQL *SELECT 3/2* will return *1*. Which is similar to what MS SQL
server and Oracle do. So all thoses databases will lose precision if you
are not carefull.

If you truly need precision you can have it by using exact numeric types
for your data types. Of course it has a cost on performance, memory and
disk usage.

The advantage of the current approach is that it give you the choice. It is
up to you to decide what you need for your application. It is also in line
with the way CQL behave everywhere else.