Re: 8.1, OID's and plpgsql

Uwe C. Schroeder wrote:
> Hi everyone,
>
> in 8.1 by default tables have no OID's anymore. Since OID's are 4 byte it's
> probably a good idea to discourage the use of them (they produced a lot of
> trouble in the past anyways, particularly with backup/restores etc)
>
> Now there's the issue with stored procs. A usual construct would be to
> ...
> ...
> INSERT xxxxxx;
> GET DIAGNOSTICS lastoid=RESULT_OID;
> SELECT .... oid=lastoid;
> ....
> ....
>
> Is there anything one could sanely replace this construct with?
> I personally don't think that using the full primary key is really a good
> option.

There we disagree. That's what the primary-key is for. Of course that
means we want a last_primary_key_from_insert() system-function.

> Say you have a 3 column primary key - one being a "serial", the
> others for example being timestamps, one of them generated with "default"
> options.

Then you have a bad primary key - the timestamps add nothing to the
serial (or vice-versa).

> In order to retrieve the record I just inserted (where I don't know
> the "serial" value or the timestamp) I'd have to
>
> 1) store the "nextval" of the sequence into a variable
> 2) generate the timestamp and store it to a variable
> 3) generate the full insert statement and retain the other values of the
> primary key
> 4) issue a select to get the record.
>
> Personally I think this adds unneccessary overhead. IMHO this diminishes the
> use of defaults and sequences unless there is some easier way to retrieve the
> last record. I must be missing something here - am I ?

Yes - add a SERIAL column with UNIQUE and fetch on that if you really
need to. This effectively gives you your OID back.

--
Richard Huxton
Archonet Ltd