On Jan 14, 1:49=A0am, aehc...@[EMAIL PROTECTED]
wrote:
> Is there a commercial RDBMS that allows one to create indices on
> views?
>
> I'm asking this partly because of BCNF.
>
> A typical BCNF problem is (where -> is a FD)
>
> A, B->C
> C -> B
>
> which becomes the following relations
>
> R_A [_A_, _C_]
> R_B [_C_, B]
>
> where _X_ denotes an attribute in the primary key
>
> since
> R [_A_,_C_,B] is not in 2NF
>
> But there's an additional constraint where the equijoin of R_A and R_B
> on C would have the candidate key A,B.
>
> Is there a way to express this last constraint (i.e., a candidate key
> on a view) in an implementation system?
>
> Cecil Chua
I'm not quite sure what you are asking, but
since a view is really just a query, then indexing it does not make
sense. The DBMS should be able to derive a query executation plan
based on the underlying tables used in the query.
If you want a theoretical answer, then post over in
comp.databases.theory
HTH
ed
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