@phdthesis{Jurk2005, author = {Jurk, Steffen}, title = {A Simultaneous Execution Scheme for Database Caching}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-228}, school = {BTU Cottbus - Senftenberg}, year = {2005}, abstract = {Database caching techniques promise to improve the performance and scalability of client-server database applications. The task of a cache is to accept requests of clients and to compute them locally on behalf of the server. The content of a cache is filled dynamically based on the application and users' data domain of interest. If data is missing or concurrent access has to be controlled, the computation of the request is completed at the central server. As a result, applications benefit from quick responses of a cache and load is taken from the server. The dynamic nature of a cache, the need of transactional consistency, and the complex nature of a request make database caching a challenging field of research. This thesis presents a novel approach to the shared and parallel execution of stored procedure code between a cache and the server. Every commercial database product provides such stored procedures that are coded in a complete programming language. Given a request in form of such a procedure, we introduce the concept of split twin transactions that logically split the procedure code into two parts, say A and B, such that A is executed at the cache and B at the server in a simultaneous and parallel manner. Furthermore, we analyse the procedure code to detect suitable parts. To the best of our knowledge, this has not yet been addressed by any existing approaches. Within a detailed case study, we show that our novel scheme improves the performance of existing caching approaches. Furthermore, we demonstrate that different load conditions of the system require different sizes of the parts A and B to gain maximal performance. As a result, we extend database caching by a new dimension of optimization, namely by splitting of the procedure code into A and B. To solve this problem of dynamically balancing the code execution between cache and server, we define the maximum performance of a database cache over time and propose a stochastic model to capture the average execution time of a procedure. Based on the execution frequencies of primitive database operations, the model allows us to partially predict the response times for different sizes of A and B, hence providing a partial solution to the optimization problem.}, subject = {Datenbankentwurf; Zugriff; Simultaneous Engineering; Datenbank-Cache-Technik; Datenbankoptimierung; Zwillingstransaktion; Database caching; Database optimization; Twin transactions; Simultaneous execution; Stored procedures}, language = {en} } @phdthesis{Steeg2000, author = {Steeg, Martin}, title = {RADD, raddstar - a rule based database schema ; compiler, evaluator, and optimizer}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000118}, school = {BTU Cottbus - Senftenberg}, year = {2000}, abstract = {The thesis discusses the problems of database development and maintenance, and presents an approach to conceptual tuning realized by conceptual design using the HERM/RADD notation. The RADD design tool has been designed in order to develope HERM specifications graphically. RADD adds semantics and operations to the design, which are not directly annotated on the graphical specification, such as "afunctional" dependencies and SQL operations and procedures. The RADD/raddstar system extends the graphical specification of the database schema with the posibility to specify the operations and with the invocations for transforming the schema, for evaluating transactions, and for optimizing the schema, each of which according the implicite requirements graphically modeled and the explicite requirements specified by means of the conceptual specification language (CSL). CSL is used as command line interface of the RADD/raddstar. The graphical RADD schema as well as the CSL specifications are compiled into terms of the RADD* data model by the system, such that these terms are used for further evaluation actions. The actions performed by the RADD/raddstar (schema transformation, transaction and cost evaluating, schema optimization) are based on rules, that can be developed and modified by the user using the CSL.}, subject = {Datenbankentwurf; Schemaevolution; Entity-Relationship-Datenmodell; Konzeptionelle Modellierung; Typinferenz}, language = {en} }