Re: [HACKERS] Another reason to redesign querytree representation

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От Bruce Momjian
Тема Re: [HACKERS] Another reason to redesign querytree representation
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Msg-id 199907202140.RAA12503@candle.pha.pa.us
обсуждение исходный текст
Ответ на Re: [HACKERS] Another reason to redesign querytree representation  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [HACKERS] Another reason to redesign querytree representation  (Tom Lane <tgl@sss.pgh.pa.us>)
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> Bruce Momjian <maillist@candle.pha.pa.us> writes:
> > Did you want to do the change for UNION, or were you just suggesting it
> > be done?  I can easily add it to the TODO list.
> > Done:
> 
> >     * redesign UNION structures to have separarate target lists.
> 
> Actually, it's not so much UNION that's busted as it is INSERT.
> The parser problems could be dealt with by having a two-level structure
> for INSERT ... SELECT ..., so that the targetlist for the eventual
> INSERT could be described without changing the semantics of the
> underlying SELECT.
> 
> There might be other extensions needed for rules (paging Jan...) but
> as far as what I've been looking at goes, the TODO entry could be just
> 
>     * redesign INSERT ... SELECT to have two levels of target list.

Removed:
* Be smarter about promoting types when UNION merges different data types
* SELECT ... UNION ... GROUP BY fails if column types disagree
* INSERT ... SELECT ... UNION is not reliable

And added:

* redesign INSERT ... SELECT to have two levels of target list

--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026
 


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