Re: Vector type (Re: challenging constraint situation -

[Alban Hertroys <alban(at)magproductions(dot)nl>]

Tom Lane wrote:
> Alban Hertroys <alban(at)magproductions(dot)nl> writes:
> > With what I have in mind, both overlap and equality would violate the 
> > unique constraint. I don't quite see why someone'd want to forbid 
> > overlap but to allow equality; isn't not allowing equality the whole 
> > point of a unique constraint?
>
> You're missing the point.  Letting "~" represent the operator that
> tests for interval-overlap, we can have
> 	A	--------------
> 	B	       ------------------

I'd say "unique constraint violation" right here (provided there's a 
unique constraint on this column, of course). The order in which these 
are inserted/updated doesn't seem to matter either. I'm afraid I'm still 
missing the point... or maybe I'm not wrong???

> 	C	                   ----------------
> so that A ~ B and B ~ C but not A ~ C.  This is too much unlike normal
> equality for a btree to work with "~" as the "equality" operator.

--
Alban Hertroys
alban(at)magproductions(dot)nl

magproductions b.v.

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