Re: The C in ACID

Paul Mansour wrote:
> I'm reading a new paper by David Lomet and Roger Barga, two respected
> (I think!) senior researchers at Microsoft, and come across the
> following in discussing the ACID properties of a DBMS:
>
> "However, these techniques [Atomicity, Isolation, and Durable], which
> are commonly known in the database technical community, do not
> entirely cope with the problem of consistency (C), which is primarily
> the responsibility of a user transaction to preserve."
>
> If the meaning of this sentence is somewhat unclear, later in the paper
> they state:
>
> "Recall that it is the user, not the database system, which provides
> the "C" in "ACID" transactions."
>
> ...which seems to unequivocally indicate a complete confusion between
> the concepts of consistency and correctness. Or am I missing something?
>
> The paper, "Recovery from Bad User Transactions" may be found here:
>
> http://research.microsoft.com/db/immortaldb/
>
> Scroll down to the bottom, its the first reference.
>

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.

p Received on Mon Aug 21 2006 - 19:03:21 CEST