Management of the Evolution of Database-Centric Information Systems

1. Management of the Evolution of Database-Centric Information Systems Panos Vassiliadis2 , George Papastefanatos1, Timos Sellis1, Yannis Vassiliou1 1 National Technical University of Athens-KDBMS Laboratory {gpapas,timos,yv}@dblab.ece.ntua.gr 2Universityof Ioannina {pvassil@cs.uoi.gr}

2. Database Schema Evolution • Current database systems are continuously evolving environments, where design constructs are • Added • Removed • Modified • Evolution is not handled by current DBMS with an automatic way • E.g., syntactic as well as semantic adaptation of queries and views: time-consuming task, treated in most of the cases manually • Evolution driven database design is missing P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

3. Empirical Studies on Database Schema Evolution Evolving Database Systems Principled Description of the architecture of a database-centric Information System Principled Response to evolutionary events Metrics Design Patterns Issues in Database Schema Evolution P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

4. Empirical Studies on Database Schema Evolution Principled Description of the architecture of a database-centric Information System Principled Response to evolutionary events Evolving Database Systems Metrics Design Patterns Empirical Studies on Database Schema Evolution • Collect test cases to come up with fundamental laws that govern database evolution • Establish an experimental protocol for monitoring existing real-world databases and discover the way they evolve • Collect such results and make them available to the research community P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

5. Empirical Studies on Database Schema Evolution Principled Description of the architecture of a database-centric Information System Principled Response to evolutionary events Evolving Database Systems Metrics Design Patterns Principled Description of the architecture of a database-centric Information System • A commonly agreed formalism to express the internals of a database-centric system • a modelof the structural properties and dynamics of database-centric systems • interdependencies in the components of a complex database-centric system • a scientific foundation for the architecture of complex database-centric systems P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

6. Empirical Studies on Database Schema Evolution Principled Description of the architecture of a database-centric Information System Principled Response to evolutionary events Evolving Database Systems Metrics Design Patterns Principled Response to evolutionary events • Forecast the impact of an evolution event • Handle conflicts • Keep versions of the database consistent to user views • Treat evolution in the presence or absence of user requirements • Automation of the reaction to changes • self-monitoring • impact prediction • auto-regulation • self-repairing P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

7. Empirical Studies on Database Schema Evolution Principled Description of the architecture of a database-centric Information System Principled Response to evolutionary events Evolving Database Systems Metrics Design Patterns Metrics • Measures for the quality of the design of a databasewrtits evolution • “Right” families of such measures P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

8. Empirical Studies on Database Schema Evolution Principled Description of the architecture of a database-centric Information System Principled Response to evolutionary events Evolving Database Systems Metrics Design Patterns Design Patterns • Come up with a well-founded theory for design patternswrt evolution • Eliminate maintenance trapsdue to ad-hoc, or complex solutions • Methods for testing database designs P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

9. Evolving databases Evolving applications Queries Database Schema Graph-based modeling for uniform representation Rules for Handling Evolution Metrics for Evaluating Evolution Design Database Schema Evolution – Our approach Graph based representation of database constructs (i.e., relations, views, constraints, queries) Mechanism for performing what-if analysis for potential changes of database configurations Annotation of graph with rules for adapting queries to database schema evolution P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

10. Graph based representation Q: SELECT EMP.Emp#, Sum(WORKS.Hours) as T_Hours FROM EMP, WORKS WHERE EMP.Emp# = WORKS.Emp# GROUP BY EMP.Emp# P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

11. Annotation of graph with rules for adapting queries to database schema evolution • Set of evolving database constructs: • relations • attributes • constraints • Set of reaction policies: • propagate • block • prompt • Set of potential evolution changes: • addition • deletion • modification According to prevailing policy, the proper action is taken  graph transformation P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

12. Annotated Query Graph Event Transformed Query Graph Add attribute Phone to EMP relation An Example P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007

13. Conclusions – Future Work • A tool for visualizing and performing what-if analysis for several evolution scenarios. • SQL extensions for annotating graph constructs with evolution semantics • Evolution-driven database design • Design patterns for allowing smooth evolution • Definition of graph based metrics evaluating the system design P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007