Re: [HACKERS] RI generic trigger procs

Jan Wieck wrote:
> 
>     Any combination of attributes in a table referenced to by one
>     or  more  FOREIGN  KEY  ...  REFERENCES constraint of another
>     table shall have a UNIQUE and NOT NULL constraint.
...
>  So we assume here that any PK is unique and cannot contain NULL's.

What is the reasoning behind requiring this ?

I can't see anything that would mandate this - * NULLs are'nt equal anyway and ar even disregarded under your
currentdescription.    Or are you just protecting yourself against the case where the    foreign key field is set to
null- could this be handled the    same as deleting for cascaded constraints ? * UNIQUE would save us the check for
existingother possible    referenced values - is this mandated by SQL spec ?
 

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Hannu