Re: Foreign keys for non-default datatypes

On Thu, Mar 02, 2006 at 08:41:20PM -0500, Tom Lane wrote:
> elein <elein@varlena.com> writes:
> > ... What I'm saying is that the opclass needs to be 
> > an option to PRIMARY KEY and FOREIGN KEY--
> 
> PRIMARY KEY and UNIQUE, you mean.
> 
> This was brought up before, but I remain less than excited about it.
> You can get essentially the same functionality by doing a CREATE UNIQUE
> INDEX command, so allowing it as part of the PK/UNIQUE syntax is little
> more than syntactic sugar.  I'm concerned that wedging opclass names
> into that syntax could come back to haunt us some day --- eg, if SQL2009
> decides to put their own kind of option into the same syntactic spot.
> 
> > The case in point is a subtype (domain) with a BTREE operator class.  
> > I can of course create a separate unique index, however, if I use the 
> > PRIMARY KEY syntax the op class of the data type is not recognized.
> 
> Hm, does CREATE INDEX work without explicitly specifying the opclass?
> I suspect your complaint really stems from overeager getBaseType() calls
> in the index definition code, which is maybe fixable without having to
> get into syntactic extensions.

I am also leary of syntactic extensions.  I've found at least one getbasetype
to be misplaced rather than over eager.  But I'm looking at these issues
as I have time available.

> 
> 			regards, tom lane
> 
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