The problem of incomplete information in relational databases (Q1202165)

In practice it is often the case that the available information is incomplete with respect to the information that is supposed to be recorded in a database. The book of the series ``Lecture Notes in Computer Science'' considers the problems raised by information incompleteness in the context of the relational model. The book consists of five chapters. Chapter 2 reviews the relational model and the operations in a uniform manner. A lattice structure on the set of all relations is imposed. Then several concepts, such as dependency satisfaction and updates can be defined in terms of operations on the lattice. Chapter 3 is a generalization of chapter 2 to the incomplete case, i.e. to sets of sets of relations. The author shows that there are two lattice structures on sets of sets of relations. The operations introduced in Chapter 2 are generalized elementwise to sets of relations, according to the basic intuitiv assumption. Chapter 4 treats the implementation of sets of relations as so called tables. A table is a relation with null values and restrictions on the null values as entries. In Chapter 5 the computational complexity of the introduced algorithms is analyzed, in the pursuit of finding a table class and a set of operations that can be efficiently implemented. In Chapter 6 the author briefly compares the results to other works, and summarizes the significant implications of the previous chapters.