Re: [HACKERS] Upgrades for 6.4.1

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От Bruce Momjian
Тема Re: [HACKERS] Upgrades for 6.4.1
Дата
Msg-id 199812192337.SAA13426@candle.pha.pa.us
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Ответ на Re: [HACKERS] Upgrades for 6.4.1  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы RE: [HACKERS] Upgrades for 6.4.1  ("Stupor Genius" <stuporg@erols.com>)
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> "Thomas G. Lockhart" <lockhart@alumni.caltech.edu> writes:
> >> * SELECT DISTINCT i FROM dtest ORDER BY j generates strange output
> 
> > In my simple test case, it orders by j, then only shows i. Is that
> > strange?
> 
> The thing that is "strange" is that you get nonunique values of i,
> which is definitely a bit unexpected for "SELECT DISTINCT":
> I don't know whether the SQL standard defines how this combination of
> features ought to work ... but our current behavior seems fairly
> surprising...

Re-added to TODO list.

> 
> 
> >> * Allow constraint NULL just as we honor NOT NULL
> 
> > Fundamental yacc problem with this as I recall. Gives rise to
> > shift/reduce problems since it is ambiguous with other uses of "NULL" in
> > the same area.
> 
> More to the point, what possible use would a column constrained to NULL
> be?  Might as well just not have it in the table...

It just says the column _may_ accept nulls.  It is the default anyway.

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