Re: [HACKERS] gram.y foreign keys

Let me know if you want to discussed this over the phone for ideas.


> OK, I've put in fixes to get Jan up and running on column foreign
> keys. The current fix forces NOT NULL arguments to be near the
> beginning of a column constraint list, and enforces the SQL92
> requirement that the DEFAULT clause occur nearly first in a column
> constraint.
> 
> As Jan probably already knows, the shift/reduce conflicts all happened
> as a result of NOT NULL and NOT DEFERRABLE clauses; removing either
> eliminated the conflicts.
> 
> I poked at it for *hours*, and have not yet stumbled on the correct
> layout to give full flexibility while allowing the new constraint
> attributes. Jan was thinking that he needed some token lookahead to do
> this, but I'll be suprised if that is required to solve this for the
> SQL92 case: it would be the first and only instance of syntax which
> can not be solved by our yacc parser and istm that the spec would try
> to stay away from that. The successful technique for fixing this will
> likely involve unrolling more clauses to allow yacc to juggle more
> clauses simultaneously before forcing a shift/reduce operation.
> 
> I'm leaving town through next weekend (back the 28th) and can pick
> this up for more work then.
> 
> btw, regression tests pass except for the rules test with known
> formatting differences.
> 
>                    - Thomas
> 
> -- 
> Thomas Lockhart                lockhart@alumni.caltech.edu
> South Pasadena, California
> 
> ************
> 


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