Re: Date and McGoveran comments on view updating 'problem'

From: <vadimtro_at_gmail.com>
Date: Thu, 11 Dec 2008 11:31:52 -0800 (PST)
Message-ID: <b32507b8-33cf-48a9-9682-cea3a5f97678_at_q26g2000prq.googlegroups.com>


On Dec 11, 5:37 am, paul c <toledobythe..._at_oohay.ac> wrote:
> In the meantime, I'd like to point out that based on
>
> http://arxiv.org/pdf/0807.3795,
>
> SP v S = S can't be true given the usual attributes Date ascribes to SP
> and S, for example Supplier_Name or somesuch is in S but not in SP.  I
> think it could be true for SP{S#, P#} V S{S#} = S{S#} with a further
> proviso that S# is a foreign key.

Correct, there is no restriction onto S and SP whatsoever. There are two natural conditions on delta relation D, however. It should have the same header as join of S and SP, and be disjoint with the S ^ SP view. Received on Thu Dec 11 2008 - 20:31:52 CET

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