Aggregates and associated relational operators
From: Mikito Harakiri <mikharakiri_at_ywho.com>
Date: Fri, 5 Sep 2003 15:49:37 -0700
Message-ID: <ry86b.30$pP2.101_at_news.oracle.com>
Date: Fri, 5 Sep 2003 15:49:37 -0700
Message-ID: <ry86b.30$pP2.101_at_news.oracle.com>
Some time ago there has been already a small thread about broken symmetry
among relational operators ("Naisetrac Product", which BTW should properly
called "Tensor Product"). Recent discussion about "fundamental" aggregates
satisfying identities like this:
sum(a union b) = sum(a) + sum(b)
max(a union b) = max(max(a),max(b))
prompts a related question:
Why union operator is so special that it has associated aggregation? Is
there anything similar to aggregation that is missing?
Received on Sat Sep 06 2003 - 00:49:37 CEST