Re: The Practical Benefits of the Relational Model

In article <aon0qq$1jak$1_at_sp15at20.hursley.ibm.com>, Paul Vernon <paul.vernon_at_ukk.ibmm.comm> wrote:
>
>"Jan.Hidders" <hidders_at_hcoss.uia.ac.be> wrote in message
>news:3dadc2d1$1_at_news.uia.ac.be...
>> >The only things they provide that cannot be done using core model
>> >concepts, are things that explicitly do not want to be in the hands of
>> >users.
>>
>> What they provide is the illusion that you are the only one who is
>> allowed to use the database at the moment and everybody else has to wait.
>
>At the cost of other users having to wait.

No, the *illusion* that the other users have to wait. How much the other users really have to wait depends upon the locking protocol.

>Optimistic locking does not provide this illusion.

What!? Are you seriously suggesting that optimistic locking protocols cannot guarantee serializability?

• Jan Hidders