Re: The C in ACID

"Paul Mansour" <paul_at_carlislegroup.com> wrote in message news:1156178886.704203.83220_at_75g2000cwc.googlegroups.com...
> 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.
>

Quoting from the abstract:

"However, user transactions can be flawed and lead to inconsistent (or invalid) states."

It's unlikely that the authors conflate consistency with validity given the above. I presume validity and correctness are both the same concept, namely consistency with the real world. Given the thrust of the article, concerned with correction of invalid states, the parentheses in the above quote were unfortunate, at best. If anything, it should have been written:

"However, user transactions can be flawed and lead to invalid (or inconsistent) states."

This would, I claim, have more clearly indicated the authors' thought. Received on Tue Aug 22 2006 - 12:36:09 CEST