Herouth Maoz wrote:
>
> At 03:48 +0300 on 02/06/1999, Michael Yeung wrote:
>
>
> > Hi all,
> >
> > Is anyone know that if we allow order-by clause in the view structure.
> > If not, how can we take the ordering of the UNION ALL in 2 different bags ?
>
> Correct me if I'm wrong, but ORDER BY shoud not be part of a view, in the
> same way it is not a part of a table. A table is defined as an unordered
> collection of tuples. In any given query, you can define the order of the
> tuples returned. But the table itself is not ordered.
>
> A view should look to the user just like a table. The order of the tuples
> is part of the query, not part of the table, and not part of the view.
That's all right and I'm not going to allow this just for the
ORDER BY. It will be enabled as kind of a side effect.
Because view's can have a GROUP BY clause, the
rewriter/planner must be able to produce plans where
different left-/righttrees have their own grouping. Grouping
requires a sort and thus sorting of subplans must be
supported.
Why should we deny ORDER BY on views explicitly?
Jan
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