Re: Re: PDF book July 2, 2000 version

Added to TODO:

* Allow oid to act as a foreign key

> Bruce Momjian wrote:
> > Can someone comment on this? Why doesn't OID work in foreign keys.
> > Seems this is a bug.
>
> The RI triggers check for attribute existance by looking up
> in the relations descriptor via SPI_fnumber(). Since OID is a
> system attribute, it returns SPI_ERROR_NOATTRIBUTE and that
> causes the error.
>
> Later on, I'm not sure that it is possible to use SPI
> functions to obtain the OID of a given trigger tuple. So it'd
> be a little more to fix it.
>
>
> Jan
>
> >
> > > First off I want to say thank your for creating a sorely needed reference and
> > > sharing it with the online world via the PDF document.
> > >
> > > I do have one minor complaint though. I'm learning Postgres from your book
> > > although I'm familiar with the basics of SQL. I was at first excited then
> > > discouraged by the OID section of your book. I think a much needed
> > > addition to the OID limitations section is that the OID field can not be
> > > referenced in a foreign key. IE
> > >
> > > CREATE TABLE t1( i INTEGER);
> > > CREATE TABLE t2( id OID REFERENCES t1(oid));//dose not work
> > >
> > > You use the OID is a foreign key of sorts in the example, but you never qualify
> > > that using the foreign key constraint system in Postgres will not allow you to
> > > automate this. I realize the OID section comes long before the constraints
> > > chapter, but a quick qualification would still make things clearer. Without
> > > the ability to use the OID field as a reference for foreign keys, it's
> > > usefulness is very limited.
> > >
> > > Keep up the good work, I can't wait to buy the finished product!
> > >
> > > _________________________
> > > Richard Rowell
> > > rrowell(at)shreve(dot)net
> > >
> > > Perl is the unix world's equivalent of VB - and just as much of an abomination.
> > >
> >
> >
> > --
> > Bruce Momjian | http://www.op.net/~candle
> > pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
> > + If your life is a hard drive, | 830 Blythe Avenue
> > + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
> >
>
>
> --
>
> #======================================================================#
> # It's easier to get forgiveness for being wrong than for being right. #
> # Let's break this rule - forgive me. #
> #================================================== JanWieck(at)Yahoo(dot)com #
>
>
>

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026