On Thursday 01 December 2005 10:24, Jaime Casanova wrote: > On 12/1/05, Uwe C. Schroeder <uwe@xxxxxxxxx> 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. 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. 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 ? > > > > UC > > If you are using a SERIAL in your PK, why you need the other two > fields? The serial will undoubtly identify a record? > > you just retrieve the current value you inserted with currval > No it doesn't. the serial identifies the record, the timestamp identifies the version/time-validity of the record. If a primary key needs to be something as simple as a serial then we could just keep the OID's as well and pump them up to 32 bytes. curval() doesn't do it, since that will only identify a group of records since my PK is not just a simple int4. sample: create table xxx ( id serial, field varchar, ... ... valid_from timestamptz ) PK is id,valid_from There may be several records with the same id but different valid_from dates. I'm storing a full timestamp, but the application only uses the date part - the timestamp is just to correct for timezones. From the application logic a record is considered valid until a record with a newer valid_from is found. From that point on the records are referenced depending on several legal factors (this is commercial insurance, lots of lawyers and state/fed regulations) I guess I either stick to the OID's which work fine, or I just have to store the whole PK in variables and forget about defaults. Why not have something like the rowid in oracle? UC
