Re: relational tables and objects

Dm. Arapov wrote:
>
>"Jan Hidders" <hidders_at_REMOVE.THIS.uia.ua.ac.be> wrote in
>
>> Who receives the 'join' message? I mean, if I join A and B do I say
>>
>> A.join(B)
>>
>> or
>>
>> R.join(A,B)
>
>Neither. The simpliest way to join tables is to call
>join_eq<list_of_columns_to_be_equal>(A,B);

Ok. So query optimization is going to be a matter of letting this function decide on the basis of the types what algorithm it is going to use? That's not really open-ended (it cannot take new table types into account without changing this function) but I don't see a way to do that anyway.

>Result of this call will be object of class join_t_eq<TableA, TableB,
>list_of_columns_to_be_equal>.

Interesting. Why is the list of columns in the type? And if I do join(A,join(B,C)) will the result have the same type as join(join(A,B),C) or not? So can you statically type the set union?

• Jan Hidders