Re: Creating indexes on views/BCNF

On Jan 14, 5:38 pm, aehc..._at_ntu.edu.sg 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_1 [_A_, _C_]
> R_2 [_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_1 and
> R_2
> 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

Hi Cecil;

Please forgive the self-promotion, but my article here: http://www.sqlservercentral.com/articles/Data+Modeling/61529/ is the 4th in a series of 5 articles on db design. It shows, specifically, how to implementa a multi-relvar constraint using an indexed view on MS SQL Server. I think there exists an analogous facility in Oracle, but I'm not sure about other DBMSs (such as MySQL).

TroyK Received on Wed Jan 16 2008 - 21:06:02 CET