Re: Re: PDF book July 2, 2000 version

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
OIDis 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@shreve.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@candle.pha.pa.us               |  (610) 853-3000
>   +  If your life is a hard drive,     |  830 Blythe Avenue
>   +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
>


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