It is known that the expression complexity and combined complexity of query evaluation in
relational databases are in general exponentially higher than the data complexity of query …

Answering queries in a relational database often requires that the natural join of two or more
relations be computed. However, the result of a join may not be what one expects. In this …

Relational databases provide the ability to store user-defined functions and predicates
which can be invoked in SQL queries. When evaluation of a user-defined predicate is …

We define the class of conjunctive queries in relational data bases, and the generalized join
operator on relations. The generalized join plays an important part in answering conjunctive …

Relational joins are at the core of relational algebra, which in turn is the core of the standard
database query language SQL. As their evaluation is expensive and very often dominated …

Introduction 314 (the second operand of the join) is the result of a join that must be
materialized in memory or-if it is too big-on disk. The heuristic saves this materialization, but …

Several aspects of relational database systems require the processing of predicates. For
example, predicates can be tested for satisfiability (as in processing predicate locks), and …

This paper examines optimization within a relational data base system. It considers the
optimization of a single query defined by an expression of the relational algebra. The …

Many database queries can be formulated in terms of expressions whose operands
represent tables of information (relations) and whose operators are the relational operations …

Recently, Gottlob, Lee, Valiant, and Valiant (GLVV) presented an output size bound for join
queries with functional dependencies (FD), based on a linear program on polymatroids …