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 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@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

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#================================================== JanWieck@Yahoo.com #

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@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

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#================================================== JanWieck@Yahoo.com #

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  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