Re: Announcing the "Instant Data Warehouse" Product

In <31222AAA.D4_at_strategy.com> "Michael J. Saylor" <saylor_at_strategy.com> writes:
>
>Regarding:
>" Deliverable ROLAP capacity may be less limited
>by theoretical database size than by performance and the hassles of
>maintaining hundreds or thousands of summary tables, so their
>deliverable capacity is not necessarily larger than MDBs, and the
>cost of their scalability is high in people and hardware costs."
>
>Nigel,
>Consider the Woolworths data warehousing project again, in light of
 the above
>comments, <snipped>

Nigel and Michael,

This is odd. Michael is correct to defend ROLAP against the ridiculous assertion by Nigel that "hundreds or thousands of summary tables" are required to get adequate performance. But I think you've gone too far by eschewing aggregates altogether, which you seem to imply by the discussion of atomic data. After all, it's the first aggregation that summarizes the most detailed data to its next level; that gives you the bang for the buck. And if you visualize the intersection of the 1/x and ln(1+x) curves (where x is the number of aggregates taken), you see that the most dramatic drop in query cost (1/x) and the smallest number of additional records to the database (ln(1+x)) occur very early. This implies that a very few aggregates can deliver dramatic improvement.

I don't think this debate is over forever, but it is clear that ROLAP is the right choice for larger databases, and especially for deep, data rich problems that involve conditional metrics based on non-hierarchical attributes (though I would be interested to hear how Acumate has apparently solved this problem). What is interesting, though, is that I don't believe that RDBMS' have an architectural advantage over MDDs. There is no reason why a MDD structure couldn't scale up to the 100GB size, or more. IN fact, Planning Sciences claims that that's exactly what Gentium DB will do later this year. Stay tuned.  

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_/ Neil Raden - nraden_at_ix.netcom.com 
_/ Archer Decision Sciences, Inc.              
_/ Data Warehouse/Decision Support Consultants       
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