Re: IBM Debunks Oracle's MultiVersion Read Consistency ?

"Noons" <wizofoz2k_at_yahoo.com.au.nospam> wrote in message news:Xns936574DDC3AFTokenthis_at_210.49.20.254...
> Following up on Robert Allen, 21 Apr 2003:
>
> > They raise some good points. Is it really as efficient as IBM suggests?
> > What are the advantages that MVRC provide?
>
> I love it when they mention stuff like:
> "This does not conform to any ANSI standard isolation level,
> nor is it the way other RDBMS's work."
>
> First: Their non-RDBMS databases used to go to great lengths to provide
> the isolation level that they "blame" Oracle for. That's how their
> Codasyl stuff works. And they go to great lengths to "prove" that
> in that "enterprise high-volume" environment it is absolutely
> essential. Sudenly with Oracle it's a "disadvantage"?
>
>
> Second: Who the F*** cares that "other RDBMS's work different"???
> Last I looked no one ANYWHERE required them to work the same way?
> Hellooooooo?
>
>
>
> And "It is true that a reader will not wait on a writer
> but it is reading old, and possibly out of date data" is
> just the biggest pile of crap I've seen!
> Oracle reads the data as consistent with the start of the query
> as it can possibly get, guaranteed, and that is "possibly out
> of date data"?
> Lights seem to be on, but is anybody home???
>
>
>
> Conveniently, they "forget" to explain exactly how much more
> "efficient" their "Repeatable Read" is... What a joke!
>
>
> The whole section on "Benchmark results" is laughable.
>
>
>
> It looks like someone at IBM has woken up (FINALLY! It's only taken
> them what, 10 years?) to the differences in locking between
> DB2 and Oracle and is now desperately trying to cover up that
> their "database" needs to lock rows to ensure consistent reads!
>
>
> Must be time for a new release of DB2, the hype is increasing...
>
> --
> Cheers
> Nuno Souto
> wizofoz2k_at_yahoo.com.au.nospam

I remember working on DB2 on a mainframe years ago and one of the problems we had was that DB2 does not support dynamic SQL.. It only seems to support dynamic SQL. We had a client/server application and everytime we would issue a select ... from table..... we would piss off the guys in development trying to bind their Cobol programs with the database. Our select would prevent them from binding their plans. Why? Well, as I said before at the time DB2 didn't support dynamic SQL really. What it would do it take our dynamic SQL , produce a plan and then bind to that plan. Then it would execute it. The problem was that since it produced a plan everytime we issued a select statement (yes, we used host variables) it would insert a row in the plan table which prevented everyone else from doing any binds. (eg those Cobol programers) So we had to run in auto commit mode.

Of course, this is clearly how a database should work, serialize most of it behind one place.
Jim Received on Mon Apr 21 2003 - 10:39:18 CDT