Re: WITH RECURSIVE patches V0.1 TODO items

On Tue, May 27, 2008 at 04:40:41PM +0900, Tatsuo Ishii wrote:
> - EXCEPT which has a recursive query name in the right hand operator
> is not allowed
>
> - function which has recursive query name as an operator is not
> allowed
>
> - subquery which includes a recursive query name is not allowed. Note
> that in the most outer query in the WITH clause subquery which
> includes a recursive query name is allowed
>
> - query which has a selection list including recursive query name
> and aggregate function is not allowed
>
> - query which has a selection list including recursive query name
> and HAVING clause
>
> - query including recursive query name and INTERSECT ALL or EXCEPT
> ALL is not allowed
>
> - query including recursive query name and FULL OUTER JOIN is not
> allowed
>
> - outer join query is not allowed if the right hand side of LEFT OUTER
> JOIN has recursive query name
>
> - outer join query is not allowed if the left hand side of RIGHT OUTER
> JOIN has recursive query name

Ah, the standard already has this. Tatsuo-san you might remember us
talking about negative subqueries. This is exactly the reason for most
of these rules. A recursively defined table referencing itself negativly
will only be evaluatable under special circumstances and with the right
set of data.

I take it all these rule refer to using the recursive query inside its
own definition. It's perfectly fine to use a recursively defined query
inside another with clause defining a different query as a subselect.

Michael
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