🚀 go-pugleaf

"Bill Todd (TeamB)" <no@no.com> escribi� en el mensaje
news:mcic30d6avuml13ilsuokrerfncilfpjtu@4ax.com...
> On Fri, 20 Feb 2004 11:12:14 +0100, "David Domingo"
> <david.domingo@starseguridad.com> wrote:
>
> >Then, what is the purpose of foreign keys with update cascade? ;)
>
> The purpose is to allow you to use an unstable attribute for the
> primary key. This does not make it a good idea. As you have already
> discovered, an unstable primary key makes replication very difficult.
> Unstable primary keys also cause concurrency problems. Suppose you
> have a table with an unstable key and this table has a one-to-many
> relationship with a table that has the cascade update option for its
> foreign key. One user changes the primary key value in the master
> table. Another user has changed one of the detail records and has not
> committed yet. Since one of the detail records is locked the primary
> key change cannot be cascaded. Depending on the transaction options of
> the user trying to change the primary key he/she will either get an
> error or hang until the user changing the detail record either commits
> or rolls back.
>
> Stability is second only to uniqueness in importance when choosing a
> primary key. If there is no attribute or combination of attributes
> that is both unique and stable use a surrogate primary key. You will
> save yourself a lot of headaches.
>




Ok thanks, but this question is one question with irony. Of course I know
what is the purpose of update cascade.

Sorry but I can't be in agreement with your exposition.

The only one change in current version of IBRepl is in UPDATE:

    update TABLE set PRIMARYKEY=NEWKEYVALUES,..... where
PRIMARYKEY=OLDKEYVALUES

But if you cant do this changes dont worry. When own replicator engine is
finished we will sent you a copy for your evaluation. That's ok?

THANKS and regards from Spain.


> --
> Bill (TeamB)
> (TeamB cannot respond to questions received via email)