Re: challenging constraint situation - how do I make it

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

Kenneth Downs wrote:
> Alban Hertroys wrote:
>
> > When encountering this problem I usually wonder why there isn't a data 
> > type that can store a timestamp and can be used to create a UNIQUE 
> > INDEX over it's values. That'd be wonderful.
> > Well, maybe one day I'll actually have time to create one...
> I tried this at trigger level.  The real bear is in the fact that there 
> are two columns, not one.  It is trivial to write an exclusion 
> constraint that disallows overlapping (including nested) values.  What 
> was hard was determining the meta-data structure, how do you have two 
> columns that are sometimes treated as one and sometimes as two?

Are you refering to a 'timespan' data type that can be determined to be 
unique?

I can see some problems there, as both value and range matter; it'd be 
similar to determining the uniqueness of an area in a rectangle (though 
1 dimensional only, of course).

I've never really dug into this, so I don't know what possibilities 
PostgreSQL offers in this field. Basing this on faith :)

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

magproductions b.v.

T: ++31(0)534346874
F: ++31(0)534346876
M:
I: www.magproductions.nl
A: Postbus 416
   7500 AK Enschede

// Integrate Your World //