Re: The Relational Model & Queries That Naturally Return Duplicate Rows

From: Erwin <>
Date: Mon, 11 Oct 2010 11:39:37 -0700 (PDT)
Message-ID: <>

On 11 okt, 17:27, Tegiri Nenashi <> wrote:
> On Oct 10, 2:35 am, Erwin <> wrote:
> > ...There,
> > "bag algebra" is investigated (and its inferiority to relational
> > algebra exposed).
> It is not that simple. Check up Green semirings

Nothing about algebra is ever as simple as two lines in a response in a forum, or as a single chapter in a book.

Does the provenance stuff convey information that cannot be represented relationally ? Does the provenance stuff convey information that is better represented as "K-relation", rather than "pure-relationally" ? The provenance stuff seems to assume that all relation values derive from database relvars (but maybe I misinterpreted this), and hence it doesn't seem to deal with things like TTM relation value selectors. Received on Mon Oct 11 2010 - 20:39:37 CEST

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