Foreign Exclusion Constraints

Hi All,

I have tables:

CREATE TABLE chromosomes (
id varchar(10) PRIMARY KEY,
location int4range
);

CREATE TABLE exons (
chromosome varchar(10) REFERENCES chromosomes(id),
strand varchar(1),
location int4range
);

I'm trying to store exons that must fit within a chromosome, but the
chromosomes all have different lengths, so I want a check constraint
so that location is contained within CHR_RANGE where CHR_RANGE is
taken from the chromosomes table.

ie, it would be something like:

FOREIGN KEY (chromosome) REFERENCES chromosomes(chromosome) USING gist
(during WITH <@ )

Can I add that constraint without a trigger?

The archives seem to say no, but I thought I'd ask...

http://www.postgresql.org/message-id/1288033876.6278.6.camel@vanquo.pezone.net
http://www.postgresql.org/message-id/CACECd8i4P4iNqUii4Lqsw0qSthawhh3gE=AtmBDSJN25qrx15g@mail.gmail.com
http://www.postgresql.org/message-id/1678334.8llTyI05Te@hek506

Thanks,
Nathan Boley