Query Results Include Information For Result Merging
http://www-db.stanford.edu/~ullman/pub/dood.ps
title{68}: A Comparison Between Deductive and
Object-Oriented Database Systems
author{18}: Jeffrey D. Ullman
TermStats{89}: (body-of-text “distributed”) 10 0.31 190
(body-of-text “databases”) 15 0.51 232