On Thu, Aug 9, 2018 at 01:11:05PM +0300, KES wrote:
> Bruce:
> >Yes, it would work, but doing that only for equality would be
> >surprising
> to many people
>
> Why surprising? It is
> [documented](https://www.postgresql.org/docs/current/static/sql-create
> table.html#sql-createtable-exclude):
> >If all of the specified operators test for equality, this is
> >equivalent to a UNIQUE constraint, although an ordinary unique
> >constraint will be faster.
>
> Thus the UNIQUE constraint is just particular case of exclusion
> constraint, is not?
Well, for me a UNIQUE constraint guarantees each discrete value is
unique, while exclusion constraint says discrete or ranges or geometric
types don't overlap. I realize equality is a special case of discrete,
but having such cases be marked as UNIQUE seems too confusing.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
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