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
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