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

2. P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007 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

3. 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 Principled Response to evolutionary events Design Patterns Principled Description of the architecture of a database-centric Information System Metrics Evolving Database Systems Issues in Database Schema Evolution

4. 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  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 Empirical Studies on Database Schema Evolution Principled Response to evolutionary events Design Patterns Principled Description of the architecture of a database- centric Information System Metrics Evolving Database Systems

5. P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007 5 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 model of 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 Empirical Studies on Database Schema Evolution Principled Response to evolutionary events Design Patterns Principled Description of the architecture of a database- centric Information System Metrics Evolving Database Systems

6. P.Vassiliadis, G.Papastefanatos, T.Sellis, Y. Vassiliou. Management of the Evolution of Database-Centric Information Systems PresDB ’07, Edinburgh, 2007 6 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 Empirical Studies on Database Schema Evolution Principled Response to evolutionary events Design Patterns Principled Description of the architecture of a database- centric Information System Metrics Evolving Database Systems

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

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

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

10. 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#

11. 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 potential evolution changes: addition deletion modification Set of reaction policies: propagate block prompt According to prevailing policy, the proper action is taken  graph transformation

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

13. 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