Обсуждение: oid and oidvector

Hi!

I'm from Brazil, and sorry about my english...
I'm having problems with the oid field, the field present in all tables. I 
wanted to use it as a foreing key betwwen too tables, but i couldn't! is it 
possible??
what about the data type oidvector?? i didn't find any documentation about 
it, i wanted to use it to keep a lot of oids of other objects... like an 
array of foreign keys, you know?

could you help me??

thanks!



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Camila Rocha wrote:
> Hi!
> 
> I'm from Brazil, and sorry about my english...
> I'm having problems with the oid field, the field present in all tables. I 
> wanted to use it as a foreing key betwwen too tables, but i couldn't! is it 
> possible??

No, you can't use oid as a foreign key.  You must use a PRIMARY column.

> what about the data type oidvector?? i didn't find any documentation about 
> it, i wanted to use it to keep a lot of oids of other objects... like an 
> array of foreign keys, you know?

oidvector is for internal db use.  It is an array of 16 oid's.

--  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,
Pennsylvania19026
 

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> No, you can't use oid as a foreign key.  You must use a PRIMARY column.

Oh?

regression=# create table foo(f1 int);
CREATE
regression=# create unique index fooi on foo(oid);
CREATE
regression=# create table bar (ref oid references foo(oid));
NOTICE:  CREATE TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
CREATE
regression=#

I agree with the advice *not* to do this, but that doesn't mean it can't
be done.
        regards, tom lane

Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > No, you can't use oid as a foreign key.  You must use a PRIMARY column.
> 
> Oh?
> 
> regression=# create table foo(f1 int);
> CREATE
> regression=# create unique index fooi on foo(oid);
> CREATE
> regression=# create table bar (ref oid references foo(oid));
> NOTICE:  CREATE TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
> CREATE
> regression=#
> 
> I agree with the advice *not* to do this, but that doesn't mean it can't
> be done.

Oh, oh, TODO has:
* Allow oid to act as a foreign key

So I should mark the item as completed?

--  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,
Pennsylvania19026
 

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Oh, oh, TODO has:
>     * Allow oid to act as a foreign key
> So I should mark the item as completed?

Guess so.  This was fixed in 7.2 IIRC.
        regards, tom lane