In article <aooo43$grg$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:3dafc37f$1_at_news.uia.ac.be...
>> 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.
>
>And on how trustworthy the other users are.
Not necessarily as much as you seem to claim. How much you depend on that
depends upon your locking protocol, and for certain optimistic locking
protocols this is just as much the case as it is in your proposal. So again,
this not an intrinsic problem in the concept of user visible transaction.
Moreover, such optimistic protocols are not under all circumstances ideal
and in some sense your proposal means that this is fixed. So the concept of
user visible transaction is in that respect better because it leaves this
choice open.
Received on Fri Oct 18 2002 - 06:21:47 CDT
