Re: are foreign keys realized as indexes?

Martijn van Oosterhout <kleptog@svana.org> writes:
> On Tue, May 08, 2007 at 02:14:54PM +0200, Felix Kater wrote:
>> There is *no complete* substitute for foreign keys by using *indexes*
>> since I'd loose the referencial integrity (whereas for unique contraints
>> there *is* a full replacement using indexes)?

> A unique index is not a "substitute" for a unique constraint, they're
> exactly the same thing. If you drop your constraint and create a unique
> index, you're back where you started. You neither added nor removed
> anything.

Well, actually you added or removed a pg_constraint entry associated
with the index ... but either way it's the unique index that really
does the work of enforcing uniqueness.

            regards, tom lane