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@debis.com (Jan Wieck) #
> 
> 
> 
> 


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