Re: View Updates Problem Statement

From: Mikito Harakiri <mikharakiri_at_ywho.com>
Date: Mon, 8 Sep 2003 19:33:37 -0700
Message-ID: <v6b7b.31$741.153@news.oracle.com>

"Mikito Harakiri" <mikharakiri_at_ywho.com> wrote in message news:BBa7b.29$741.241_at_news.oracle.com...
> Database A has relations RA1, RA2, RA3, ...
> Database B has relations RB1, RB2, ...
>
> Views V1, V2, V3, ... establish the mapping between the 2 databases:
>
> V1*RA1 = RB1
> V2*RA2 = RB2
> ...

Terminology sucks. Since now on by "view" I assume an operator transforming input relation into output relation (while the literature calls a view just an output relation variable). That definition is more consistent with algebraic view update ideas that I'm trying to convey.

Next correction involves the equation above. Clearly V1 can be applied to any number of input relation, not to RA1 only. Therefore, it has to be

V1*(RA1, RA2, ...) = RB1
V2*(RA1, RA2, ...) = RB2

Note nice symmetry: we have an input "vector" of relational variables (RA1, RA2, ...) transformed by the system of views V1,V2,... into the output vector of relational variables (RB1, RB2, ...) Received on Mon Sep 08 2003 - 21:33:37 CDT