Hi Craig, > Using both identity and sequence makes sense for schema generation > where you want the identity strategy (JDO implementation doesn't > generate key values) and automatic key generation using the sequence > named (JDO implementation generates the trigger and stored procedure > to use the named sequence).
JPOX doesn't support creation of trigger/storedproc for using sequences like this currently. We could just retrieve the value from the sequence and use that in the INSERT (which is what we do with strategy="sequence" anyway). Whether the JDO impl uses triggers/storedprocs is its decision isn't it ? How would a TCK be able to check what the impl was doing ? ;-) >> So how do you specify MySQL "autoincrement" if you remove this ? >> They aren't "IDENTITY" type. > > It seems that the functionality is identical to IDENTITY as defined > by SQL 2003. Internally JPOX treats "identity" and "autoassign" identically, so this part would actually simplify things slightly for us, and causes no issue that I know of. > I'd say strategy="identity" with no sequence means use the > GENERATED ... AS IDENTITY. Yes, or "autoincrement", or probably "SERIAL" too. > strategy="identity" with sequence also specified means use a trigger > and stored procedure to generate key values. Yes, but with my comments above. > strategy="sequence" means use the named sequence explicitly in insert statements, as in INSERT INTO EMPLOYEE (ID, NAME) VALUES (named_sequence.nextval, ?). Yes, although the implementation needs to know the value being used so would likely do the "nextval" call first and plug the value into the INSERT. -- Andy
