I never wondered about that situation but I thought I would ask for feedback. Basically, it never caused me any problem but here is the situation.

When doing a SQL, such as:

SELECT MyField FROM Parent;
 INNER JOIN Child ON Parent.Numero=Child.ParentNumero;
 INTO CURSOR Temp

Assuming Parent.Numero is having a type of Integer and Child.ParentNumero is having a type of Numeric(6), would that be optimized? So, in order to be fully optimized, should the types be all the same?