Re: The C in ACID

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Mon, 21 Aug 2006 17:21:08 GMT
Message-ID: <8YlGg.56938$pu3.628635@ursa-nb00s0.nbnet.nb.ca>

Paul Mansour wrote:
> paul c wrote:
>

>>My guess is that they're saying, to turn it around a bit, that the user
>>must not be allowed to pervert the dbms purposes of A,I and D.  And that
>>the user (or DBA) must tell the dbms how to test for Consistency.  It's
>>true that most systems usually require the user to tell them where a
>>transaction starts and where it finishes, but that's different from
>>telling it how.

>
> No, I don't think so. Explaining "Consistency" they write:
>
> "There is no system mechanism that prevents a user from entering a bad
> transaction, e.g., crediting the wrong amount to a bank account, or
> charging for an item that was not shipped."
>
> This is clearly referring to correctness, no?
>
> I was under the impression that the terminolgy and interpretation of
> ACID was pretty much agreed on, but this paper call the 'C' Consistency
> but appear to mean "Correctness."

It sounds to me like they are confusing internal predicates and external predicates. The dbms enforces consistency or correctness as far as the internal predicate goes. As such, the dbms can only enforce plausibility so far. Nothing can stop the user from lying to the dbms as long as the lie is plausible according to the internal predicate.

Reducing unintentional lies is the domain of usability and HCI. Reducing intentional lies is the domain of policing. Received on Mon Aug 21 2006 - 12:21:08 CDT