Re: Views for denomalizing
Date: Sun, 06 Feb 2005 20:37:51 GMT
Message-ID: <zevNd.1726$UX3.576_at_newsread3.news.pas.earthlink.net>
Alan,
>> Yes it does. Tables are a physical implementation of a logical design.
>> Views are a further implementation based on the physical tables. I think
>> we really agree here, but we are getting hung up on semantics. Something
>> can be physical _and_ logical. Views are physical in that they are
>> constructed by code, and a representation of them is stored
Considering the commonly accepted definitions of conceptual, logical and physical levels of data representations, what you are stating is utter nonsense. You may want to get your hands on ISO standards vocabulary for such definitions rather than fabricating them on your own. All good relational text books have this distinction detailed and so many quick references are out there, for instance use: citeseer.ist.psu.edu/5334.html
>> An instantiated view is a representation of data in one or more tables.
>> The view itself has no normal form. It may present a representation of
>> data in an NF other than that which that data is really stored.
This is misinterpretation of basic notion of relations. Tables as well as views are simply relation variables which are logical constructs and have nothing to do with physical models. Relations can be either base relations or derived ones. Views are derived relations; snapshots are derived relations; stored joins are derived relations. And normalization higher than 1NF can be applied to both base and derived relations. Dawn's question addresses only the views based on multi-table joins which is just one way of declaring a view.
-- AnithReceived on Sun Feb 06 2005 - 21:37:51 CET