Jay Walters wrote:
> Now in EJB 2.0 it would be much easier to implement immutable primary keys
> in the CMP environment because of the abstract persistence schema. The
> implementation class could throw an exception on change of primary key
> fields. Do you guys think this should be done, or still left open?
> Personally I'd like some option to go either way.
The latest spec does not permit changes to primary key fields for CMP.
> Cheers
> Jay
>
> -----Original Message-----
> From: Cedric Beust
> To: [EMAIL PROTECTED]
> Sent: 4/4/01 4:57 PM
> Subject: Re: EJB 1.1 and change of primary key values
>
>
>> From: Dave Wolf
>
>
>> Its an interesting question whether the pk is semantically immutable.
>
> I
>
>> dont see the spec every lay this out as a requirement. Secondly, if
>
> we're
>
>> persisting to an RDBMS which 90% of people are, the RDBMS does
>
> actually
>
>> allow updates on the PK field. So this PK mutability can occur
>
> actually
>
>> outside the EJB and bring about the same issue. Since neither EJB nor
>
> the
>
>> RDBMS enforce the relational models view that nothing changes the PK
>
> value
>
>> (a natural key) then how can we assume it is immutable?
>
>
> Because it doesn't make sense otherwise? :-)
>
> For example, Hashtable doesn't specify that equals()/hashCode() need to
> return the same value after the object has been stored in the table, but
> the
> behavior is unpredictable if they don't.
>
> Not hard to extend this consideration to PK's.
>
> Be nice to the container and the container will be nice to you :-)
>
> --
> Cedric
>
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