Re: [HACKERS] create view as select distinct (fwd)

Perhaps we should issue an error message if this is attempted until we
get it working?

> Oleg Broytmann wrote:
>
> >
> > Hello!
> >
> > VIEW on 6.4.2 ignores DISTINCT. Is it a bug? known?
> >
>
> It's a known missing feature (not a bug - more like a design
> fault).
>
> DISTINCT is implemented as a unique sort step taken over the
> final result of a query. Views are implemented via the query
> rewrite rule system. If now someone would define a DISTINCT
> view and selects a join of it with another table, the rewrite
> system cannot tell the planner that only the scan's resulting
> from the view should be sorted unique. It could only tell
> that the entire result should be DISTINCT - what's wrong - so
> I left it out.
>
> I'm planning to implement some kind of subquery rangetable
> entries someday. At that time, all these problems (DISTINCT,
> GROUP BY, ORDER BY) of views will disappear.
>
>
> Jan
>
> --
>
> #======================================================================#
> # It's easier to get forgiveness for being wrong than for being right. #
> # Let's break this rule - forgive me. #
> #======================================== jwieck(at)debis(dot)com (Jan Wieck) #
>
>
>
>

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