This book is focused on the performance evaluation of database machines, i.e., special-purpose architectures specifically meant to improve the efficiency of database applications. The topic is of primary interest because of the need to compare these systems among themselves and with traditional database management systems. The book gathers the experience of several European research groups in modeling and analyzing the database machine architectures they have proposed. It deals both with the main methodological issues and with the detailed analysis of some relevant problems. It also includes an extensive annotated bibliography with more than one hundred references and several keys for the access to the literature.