Advanced Databases Introduction

1. Advanced DatabasesIntroduction dr. Toon Calders prof. dr. Jan Paredaens

2. Outline • Motivation for the course • Other DH courses • Practical organization • Course topics • Project • Overview of changes

3. Motivation for the Course • Database = a piece of software to handle data: • store, • maintain, and • query • Most ideal system situation-dependent • data type: simple / semi-structured / complex / … • types of queries: simple lookup / analytical / … • type of usage: multi-user / single-user / distributed / … • …

4. Motivation for the Course • Relational databases are tuned towards: • simple data • simple, ad-hoc queries • multiple users • Other models are more suitable for other types of data • Object-Oriented, • Deductive, • Semi-Structured Databases, • Data warehouses

5. Motivation for the Course • Study different data models • Advantages, disadvantages • Conceptual level • what are the important notions? • What’s underneath? • In a scientific way • exact, not just claims

6. Motivation for the Course • Student knows: • different database models • Understands: • why they are introduced • conceptual notions • Is able to: • quickly master vendor-specific products

7. Outline • Motivation for the course • Other DH courses • Practical organization • Course topics • Project • Overview of changes

8. Other DH Courses • Relational database systems (2ID05) Databases and Data Modelling (2ID35) Database Technology transations, indexing, query optimization, distributed DB • Other database models (2ID45) Advanced Databases • (2II15) Data Mining • (2ID25) Information Retrieval • (2ID99) Capita Selecta DH

9. Outline • Motivation for the course • Other DH courses • Practical organization • Course topics • Project • Overview of changes

10. Practical Organization In principle … • Wed 8:45  10:30 Practical session M 1.46 • no new material • opportunity to practice, ask questions • together solve exercises • Fri 10:45  12:30 Lectures HG 6.09 • XML : Paredaens (6 lectures) • other parts: Calders

11. Practical Organization • Important information http://wwwis.win.tue.nl/~tcalders/teaching/advancedDB/ • Subscribe to 2ID45 on studyweb ! • messages to the whole class group • lecture postponed, room changes, … • t.calders@tue.nl

12. Practical Organization • Course material • Book: Silberschatz, Korth, Sudarshan. Database system concepts 5th edition. McGraw-Hill International • Lots of additional material on course webpage • papers • slides • solutions to exercises • …

13. Practical Organization • Grades: • 70% written exam • 30% group project • No project = no grade • Grade for the project can be transfered to August, similar for grade for the exam • Grades expire in August

14. Outline • Motivation for the course • Other DH courses • Practical organization • Course Topics • Project • Overview of changes

15. Course Topics • Limitations of the relational model • Deductive databases • Object-Oriented Databases • Data Warehousing & OLAP • Semi-Structured data

16. Limitations of the relational model • Not every query can be expressed • Transitive closure cannot be expressed in Relational Algebra • Give all cities reachable from Antwerp by plane • Give all smallest components of a part • Give all decendants of person X • Not even if you’re very smart … • proof • Extension to other relational query languages

17. Deductive Databases • Motivation is two-fold: • add deductive capabilities to databases; the database contains: • facts (intensional relations) • rules to generate derived facts (extensional relations) Database is knowledge base • Extend the querying • datalog allows for recursion

18. Deductive Databases • Datalog as engine of deductive databases • similarities with Prolog • has facts and rules • rules define -possibly recursive- views • Semantics not always clear • safety • negation • recursion

19. Deductive Databases g(a,b). g(b,c). g(a,d). reach(X,X) :- g(X,Y). reach(X,Y) :- g(X,Y). reach(X,Z) :- reach(X,Y), reach(Y,Z). node(X) :- g(X,Y). node(Y) :- g(X,Y). unreach(X,Y) :- node(X), node(Y), not reach(X,Y).

20. Deductive Databases • In this topic we study: • How to handle negation and recursion in the same program • How to efficiently evaluate Datalog queries

21. OO Databases • Many applications require the storage and manipulation of complex data • design databases • geometric databases • … • Object-Oriented programming languages manipulate complex objects • classes, methods, inheritance, polymorphism

22. OO Databases • Very simple example: • Class book • set of authors • title • set of keywords Extremely simple to model in OO language Hard in relational database!

23. OO Databases • In many applications persistency of the data is nevertheless required • protection against system failure • consistency of the data • Mapping: object in OO language  tuples of atomic values in relational database is often problematic

24. OO Databases • Either we ignore the multivalued dependencies • This table is in 3NF, BCNF

25. OO Databases • Or we go to 4NF

26. OO Databases • Basically OODB = persistent OO programming language • Very important concept • rather uninteresting scientifically • This topic will mainly be self-study • Reading bookchapter + Q & A session

27. Monitor & Integrator OLAP Server Metadata Analysis other sources Serve Data Warehouse Extract Transform Load Refresh Query/Reporting Operational DBs Data Mining ROLAP Server Data Marts Data Sources OLAP Engine Front-End Tools Data Storage Data Warehousing & OLAP

28. Transaction processing Operational setting Up-to-date = critical Simple data Simple queries; only « touch » a small part of the database Flight reservations ticket sales do not sell a seat twice reservation, date, name Give flight details of X List flights to Y Data Warehousing & OLAP

29. Decision support Off-line setting « Historical » data Summarized data Integrate different databases Statistical queries Flight company Evaluate ROI flights Flights of last year # passengers per carrier for destination X Passengers, fuel costs, maintenance info Average % of seats sold/month/destination Data Warehousing & OLAP

30. Data Warehousing & OLAP • In this topic we will study: • Conceptual models for decision support • Database explosion problem • Efficient implementation strategies • indexing, view materialization

31. XML • Why is XML important? • simple open non-proprietary widely accepted data exchange format • XML is like HTML but • no fixed set of tags • X = “extensible” • no fixed semantics (c.q. representation) of tags • representation determined by separate ‘stylesheet’ • semantics determined by application • no fixed structure • user-defined schemas

32. XML <PersonList Type="Student" Date="2004-12-12"> <Title Value="Student List"/> <Contents> <Person> <Name>Jan Vijs</Name> <Id>11</Id> <Address> <Number>123</Number> <Street>Turnstreet</Street> </Address> </Person> <Person> <Id>66</Id> <Address> <Street>Hole Rd</Street> </Address> </Person> </Contents> </PersonList>

33. XML • In this topic: • XML • XQuery, XSLT • LiXQuery • Taught by prof Paredaens

34. Outline • Motivation for the course • Other DH courses • Practical organization • Course Topics • Project • Overview of changes

35. Project • Pick one of the 4 topics: • deductive databases / rule-based systems • object-oriented databases • data warehouses • semi-structured databases • Formulate your own project • illustrating the different course concepts • showing you mastered the technology

36. Project • Make a project proposal ( WEEK 10 ) • examples of last year will be given • fulfilling certain constraints • listing technologies to be used • Status report ( WEEK 15 ) • Final report ( WEEK 20 ) • Project presentations ( WEEKS 21 & 22 )

37. Outline • Motivation for the course • Other DH courses • Practical organization • Course Topics • Project • Overview of changes

38. Overview of Changes • First some facts and figures regarding Spring 2008 • Heterogeneous group • Outside NL, HBO, BSc TU/e CSE BIS

39. Overview of Changes • Some suggestions I decided to act upon: 1. Start with the difficult material: • expressiveness of RA • Gaifman locality 2. Too much time is being spent on XML • (5+5)  (6+3) & topic (XSLT) has been added 3. Disproportional weight given to XML in exam • project no longer exclusively XML

40. Overview of Changes • Some suggestions I decided to act upon: 4. Some materials and instruction just too hard • extra exercices will be added; more modular 5. The course was split up in lots of individual subjects, with no apparent relation to one another • tried to handle that in the course motivation

41. Overview of Changes • Some suggestions that were ignored: A google for 'advanced databases' returns quite some courses from other universities that look interesting to me. Perhaps the lecturers could take a look at those. • When (re-)constructing the course last year other universities’ ADB courses were surveyed. Many of the interesting topics are already handled in other courses (Data Mining, Information retrieval, Database technology)

42. Overview of Changes • Some suggestions that were ignored: Don't discuss prerequisite knowledge too much, it is prerequisite.  Heterogeneous group. Balance the course subjects more, TC was discussed very specific while the other 3 subjects where treated in global.  Time spent on TC is justified by its difficulty and its importance for database theory + motivates OODB & Deductive DB

43. Overview of Changes • Take-away message • (some?) lecturers do act on questionnaires • filling out the questionnaires is useful

44. Overview of Changes • Take-away message • (some?) lecturers do act on questionnaires • filling out the questionnaires is useful

45. Summary • Relational model has limitations • simple queries • simple data • OODBs allow complex data types • Deductive databases, datalog complex queries • Somewhere in-between: datawarehouses and OLAP • special requirements, special datastructures • Semi-structured data can be stored in XML • Project complements theoretical lectures • Instructions for clarification

46. !! See you on Friday !!