Re: Serializability of Transactions and Automatic (Number) Generators

From: Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be>
Date: Tue, 30 Nov 2004 23:45:00 GMT
Message-ID: <0C7rd.5858$cB1.283756_at_phobos.telenet-ops.be>

Marshall Spight wrote:
> "Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message news:Xxspd.655$nN1.57401_at_phobos.telenet-ops.be...
>

>>If you think of the generated values as abstract identifers (and that is
>>actually what they are supposed to be) then the semantics of your
>>transaction become non-deterministic functions (aka binary relations),
>>although in a very limited sense because the only thing that is not
>>determined is the exact value of the generated values.

>
> This suggests that there might be some value in a data type for abstract
> identifiers. It is a little weird that we use integers for keys so often,
> when there is nothing otherwise integer-like going on.

Indeed. The integers are in many ways just a clumsy hack and it is at least conceptually more correct to model them as abstract identifiers. [Quoted] What is chosen to represent the identifiers is an implementation detail and has no place in the logical model. In fact, this was already recognized earlier on by the theorists and there has been some very interesting research on that, but at the time this was sold under the flag of "object oriented" and sometimes called "object identifiers" so the relational fundamentalist are still very uneasy about it.

• Jan Hidders

Received on Wed Dec 01 2004 - 00:45:00 CET