Re: [HACKERS] Enhancing PGSQL to be compatible with Informix SQL

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От Rod Chamberlin
Тема Re: [HACKERS] Enhancing PGSQL to be compatible with Informix SQL
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Msg-id Pine.LNX.4.10.10001071433520.14942-100000@shiela.querix.co.uk
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Ответ на Re: [HACKERS] Enhancing PGSQL to be compatible with Informix SQL  (Thomas Lockhart <lockhart@alumni.caltech.edu>)
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On Fri, 7 Jan 2000, Thomas Lockhart wrote:

> > the best would be to implement ANSI outer joins, and then use the 
> > rewriter to allow for the Oracle syntax, or something similar, just to 
> > add readability to the SQL.
> 
> When I tried adding the syntax to gram.y a while ago it gave
> shift/reduce errors on the "(+)" fields. I would guess that we would
> need to have this become a token in the lexer :((
> 

I'd actually expect a potential reduce/reduce conflict between:

a_expr:func_name '(' ... ')'and a_expr '(' '+' ')'

since func_name is a ColID as is a_expr potentially, so the system must
work out whether the ColID reduces to an a_expr when it sees then '('
which it can't do (it needs another token to work that out).

So yes, you probably need a new lexer token.

> I'll have the code in gram.y (commented out) when I commit my next
> changes for this; someone can play with it if they want.
> 
>                     - Thomas
> 
> -- 
> Thomas Lockhart                lockhart@alumni.caltech.edu
> South Pasadena, California
> 

.............................Rod

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