Re: Inconsistent results for division and multiplication operations

If the number of significant digits in the input is not fixed, it becomes challenging to achieve consistent results by rounding.

for example

postgres=# select round(1.003/1.002*5.01,2);

         ?column?

--------------------------

 5.01  

(1 row)

postgres=# select round(1.003*5.01/1.002,2);

      ?column?

--------------------

 5.02

(1 row)

Correct. That's why you should always use numeric with the desired precision if you want precision numbers.

for instance
select 1.003/1.002*5.01 :: numeric(10,4)
will give the same result as
select 1.003*5.01/1.002 :: numeric(10,4)

They are much slower to calculate than floating point, however, so if you don't care about precision you can keep using just floating point.

Regards,