Temporal queries in OLAP

Abstract

Commercial OLAP systems usually consider OLAP dimensions as static entities. In practice, dimension updates are often necessary in order to adapt the multidimensional database to changing requirements. We have already defined a taxonomy for these dimension updates in previous works, and a minimal set of operators to perform them. In this paper, we show the need to keep track of the history of the data warehouse. In order to address this problem, we propose a new (temporal) multidimensional model, along with a query language supporting it. We formally define the model, introduce the language by means of examples, and define its syntax and semantics. Finally, we discuss implementation issues, and how a translation into SQL:99, TSQL2 or other SQL-based languages can proceed.