Re: Warehousing : Constraints

The fact thatg 9i now allows you to put constraints on views (albeit disabled and not validated) is a clear indication that data warehouses need constraints defined left, right and centre. The point of the new feature was that data warehouses often used views and Materialized Views to speed things up -but that left the optimiser completely blind to the relationships between the underlying tables, and hence resulted in sub-optimal execution plans.

Now that you can create purely declarative constraints on the views involved, the optimizer has a much better chance of getting it right.

So, yes: you need constraints.

Regards
HJR

--
Resources for Oracle: http://www.hjrdba.com
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"Billy Verreynne" <vslabs_at_onwe.co.za> wrote in message
news:9svron$3sf$1_at_ctb-nnrp2.saix.net...


> Are constraints (especially foreign key constraints vs. indexes) a good or

bad


> idea in data warehousing?

>

> Or does this come down to a purist vs. non-purist view?

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> --

> Billy

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