Management of the Evolution of Database-Centric Information Systems Panos Vassiliadis 2, George Papastefanatos 1, Timos Sellis 1, Yannis Vassiliou 1 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.gr2 University of Ioannina

{[email protected]}

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

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Database Schema Evolution

Current database systems are continuously evolving environments, where design constructs are

AddedRemovedModified

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


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Empirical Studies Empirical Studies on Database on Database

Schema EvolutionSchema Evolution

Principled Principled Response to Response to evolutionary evolutionary

eventsevents

Design PatternsDesign Patterns

Principled Principled Description of the Description of the architecture of a architecture of a database-centric database-centric

Information Information SystemSystem

MetricsMetrics

EvolvingDatabaseSystems

Issues in Database Schema Evolution


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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 Empirical Studies on Studies on Database Database Schema Schema

EvolutionEvolutionPrincipled Principled

Response to Response to evolutionary evolutionary

eventsevents


Principled Principled Description of Description of

the architecture the architecture of a database-of a database-

centric centric Information Information

SystemSystem

MetricsMetrics



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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




eventsevents





SystemSystem

MetricsMetrics



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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-monitoringimpact predictionauto-regulation

self-repairing




eventsevents





SystemSystem

MetricsMetrics



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Metrics

Measures for the quality of the design of a database wrt its evolution

“Right” families of such measuresEmpirical Empirical

Studies on Studies on Database Database Schema Schema



eventsevents





SystemSystem

MetricsMetrics



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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 Empirical

Studies on Studies on Database Database Schema Schema



eventsevents





SystemSystem

MetricsMetrics



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Database Schema Evolution – Our approach

Mechanism for performing what-Mechanism for performing what-if analysis for potential changes of if analysis for potential changes of

database configurationsdatabase configurations

Evolving databases

QueriesDatabase Schema

Graph-based modeling

for uniform representation

Rules for Handling Evolution

Metrics for Evaluating Evolution

Design

Evolving applications

Graph based representation of Graph based representation of database constructs (i.e., database constructs (i.e., relations, views, constraints, relations, views, constraints, queries)queries)

Annotation of graph with rules Annotation of graph with rules for adapting queries to database for adapting queries to database schema evolutionschema evolution


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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#


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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


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An Example

from

map-select

S

Q

SS

EMP

Emp# NameEmp#

NameS

map-select

...

On attribute addition To EMPTHEN propagate

Annotated Query Graph Event

Add attribute Phone to EMP relation

Phone

from

map-select

S

Q

S SS

EMP

PhoneEmp# NameEmp#

NameS

map-select

...

On attribute addition To EMPTHEN propagate

S

map-select

Transformed Query Graph


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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 designDesign patterns for allowing smooth evolutionDefinition of graph based metrics evaluating the system design

Documents

Management of the Evolution of Database-Centric Information Systems Panos Vassiliadis 2, George Papastefanatos 1, Timos Sellis 1, Yannis Vassiliou 1 1