# Re: Can relational alegbra perform bulk operations?

Date: Tue, 29 Sep 2009 12:25:42 -0700 (PDT)

Message-ID: <89eeb005-052c-4416-8097-e7980628ae41_at_v15g2000prn.googlegroups.com>

On Sep 29, 11:23 am, Banana <Ban..._at_Republic.com> wrote:

> I'm new to relational theory, having read a C.J. Date's book but I worry

*> that I may have picked up mistaken impression about the relational
**> theory and thus want to validate whether my understanding is accurate or
**> not.
**>
**> Prior to reading the book, I've always had understood that anything we
**> ... We can see how much relational
**> algebra/calculus can help us optimize any kind of queries by
**> transforming the expression.
*

> But... I don't see any means within the relational algebra that provides

*> a way of evaluating multiple tuples in one go. Considering that a
**> relation is essentially a collection of propositions conforming to a
**> given predicate, it seems necessary to evaluate each tuples to determine
**> whether they should participate in the join or not, satisfy the restrict
**> condition and other things. For a lack of better terms, there is no
**> "sieve" we can employ to evaluate a set of tuples in one go.
**>
**> Is the preceding paragraph accurate?
*

It is too vague. Algebras, in general, don't care about the structure of their elements; relational algebra, in particular, doesn't refer to tuples. (BTW the fact that it refers to attributes is a flaw -- c.d.t regulars might have already guessed I'm about to sing the familiar relational lattice tune:-) Received on Tue Sep 29 2009 - 21:25:42 CEST