Re: Foreign key constraint accepted even when not same

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>, Jean-Christian Imbeault <jc(at)mega-bucks(dot)co(dot)jp>, postgresql <pgsql-general(at)postgresql(dot)org>
Subject: Re: Foreign key constraint accepted even when not same
Date: 2003-09-25 02:08:48
Message-ID: 200309250208.h8P28md27643@candle.pha.pa.us
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Tom Lane wrote:
> Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com> writes:
> > On Mon, 22 Sep 2003, Jean-Christian Imbeault wrote:
> >> Is it right for postgres to accept a foreign key constraint when the
> >> type of the field is not the same as that of the foreign key?
>
> > IIRC in SQL92 it's said that they need to be the same type, but in SQL99
> > it says that the two types must be comparable. We basically implement the
> > latter, basically using the existance of a usable equality operator as the
> > determination of comparable.
>
> Note however that performance may be poor with a cross-type foreign key
> reference, if the planner is unable to figure out how to use an index
> for the check queries.

Didn't we agree to throw a NOTICE in cases of a mismatch? (I think
Peter agreed to a NOTICE but not a WARNING) Is that completed?

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