Re: TRM - Morbidity has set in, or not?
Date: Fri, 19 May 2006 09:30:59 GMT
Message-ID: <nfgbg.40965$P2.26775_at_tornado.ohiordc.rr.com>
Keith H Duggar wrote:
[snip]
A particular network may be very convenient
> for one analysis and a nightmare for other. I'm beginning to
> understand this is the concept of "access paths" correct?
> And that a network model encodes and optimizes a particular
> access path whereas a relational model does not? And thus a
> RM allows many access paths? Efficiently?
There are a couple other implementation details that can cause trouble. One is that indices cannot be arbitrarily large. This means that you can store, typically, up to 2^31 records in a table -- but not one more. Another is that maintenance of bitmapped join indices is expensive -- so expensive, in fact, that some products do that work "in the background" with the consequence that the last "committed update" might not be visible to another program.
> I realize that those questions are somewhat flawed because
> matters of implementation, efficiency, etc are orthogonal
> (partially? totally?) to the relational data model
And, in fairness, to the network model, too. The gotchas I cited above are "implementation tradeoffs."
[snip] Received on Fri May 19 2006 - 11:30:59 CEST