Introduction

The central goal of this document is to provide the temporal database community with a comprehensive consensus benchmark for temporal query languages that is independent of any existing language proposal.

This is not a performance benchmark, but is rather a semantic benchmark intended to be an aid in evaluating the user-friendliness of proposals for temporal query languages. Thus, temporal query languages should ideally be able to express the benchmark queries both conveniently and naturally.

To obtain a consensus benchmark, researchers in temporal databases were invited to participate in this initiative, and each researcher that contributed significantly is a coauthor. The electronic mail distribution tsql@cs.arizona.edu was used as the medium for discussing the benchmark and related issues.

The benchmark consists of a database schema, an instance for the schema, and a set of queries on the this database. The queries are classified according to a taxonomy, which is also part of the benchmark. As a consequence of the central goal above, no existing temporal data models are used or mentioned. The relation schemas of the benchmark are expressed as sets of attributes, including one attribute illustrating user-defined time. However, the underlying temporal aspects are implicit (of course, specific temporal data models might add explicit temporal attributes). The contents of the relations are described in natural language. The benchmark queries are also given only in natural language. The taxonomy is independent of any particular temporal query language.

The benchmark is not intended to constitute a metric for query language completeness, and as such it is not a substitute for a rigorous theoretical study of expressive powers of various temporal query languages. Comprehensiveness of the benchmark is desirable only to ensure that a wide range of query language design aspects are covered.

It it emphasized that using the benchmark as an advanced, quantitative scoring system for comparing languages makes little sense. Thus, one language is not necessarily superior to another just because one is capable of expressing more benchmark queries than the other. Rather, the focus is on user-friendliness.

The presentation is structured as follows. Below, the intended scope of the benchmark is defined. Sections , , and  first state criteria for what should be required from a suitable database schema and instance and classification scheme, respectively. Second, an actual schema, instance, and classification schema is presented. The main body of the paper is Section , which presents, using the classification scheme, approximately 170 benchmark queries. Comments related to this benchmark, by identified contributors, are included as appendices at the end.