The Adaptation Model of a Runtime Adaptable DBMS Florian Irmert, Thomas Fischer, Frank Lauterwald, Klaus Meyer-Wegener Friedrich-Alexander University of Erlangen and Nuremberg Department of Computer Science Chair for Computer Science 6 (Data Management) Martensstrasse 3 91058 Erlangen, Germany {florian.irmert, thomas.fischer, frank.lauterwald, kmw}@cs.fau.de Abstract. Nowadays maintenance of database management systems (DBMSs) often requires offline operations for enhancement of function- ality or security updates. This hampers the availability of the provided services and can cause undesirable implications. Therefore it is essen- tial to minimize the downtime of DBMSs. We present the CoBRA DB (Component Based Runtime Adaptable DataBase) project that allows the adaptation and extension of a modular DBMS at runtime. In this paper we focus on the definition of an adaptation model describing the semantics of adaptation processes. 1 Introduction In recent years the database community has realized that common database systems do not fit into every environment [6]. The obvious solution is the devel- opment of specialized DBMSs for each environment. However this approach is not suitable with respect to development cost, time to market and maintenance. Tailor-made DBMSs [5] try to answer this challenge by adapting a DBMS towards a specific environment by providing a common code base from which customized DBMSs may be derived. Changing the functional range of such a DBMS however requires a shutdown and redeployment of a new version. Taking an application offline is often not feasible in some environments. In the CoBRA DB (Component Based Runtime Adaptable DataBase) project [2] we propose an approach to tailor a DBMS at runtime. It uses a kind of DBMS “construction kit” and basic modules that are necessary in every DBMS. A DBMS can be assembled by choosing the appropriate modules for the intended functionality of the system. An important challenge is the modification of modular DBMSs at runtime. In our prototype it is possible to add, exchange, and remove modules while the database system is running. As a foundation we have developed an adaptation framework [3] that provides the exchange of com- ponents at runtime in a transparent and atomic operation. In this paper we present the adaptation model of CoBRA DB and its adaptation types.