1. Object Oriented & Object Relational Databases
Ranga Raju Vatsavai
Teaching Mentor (Prof. Shekhar)
CSci 5708 : Architecture and Implementation of Database Management Systems, Fall 2003
Week 15 (11/24, 11/26/03) Lecture Notes

2. Outline for today 11/24/03 Objectives Introduction OO Fundamentals
Need for OO/OR-DBMS
OO Fundamentals
How (OO)DBMS incorporates OO ideas
Database Modeling/Querying
Conclusions
OODBMS
ORDBMS
Conceptual
ODL/UML
EER/PEER

3. Outline for next class 11/26/03
Objectives
ORDBMS Fundamentals
How ORDBMS incorporates OO ideas
Mapping Conceptual Model into Logical Model
OQL vs. SQL-99
Comparison of OODBMS and ORDBMS
Conclusions

4. Learning Objectives Basic concepts of OO and OR models
Extensions at conceptual modeling
Mapping Conceptual Model into Logical Model
Exposure to additional features in SQL:1999 standard.
Ability to model and implement a broader class of applications (spatial, multimedia, engineering, biological, scientific, …)

5. Introduction Why OODBMS?
Let us start with modeling this simple example in a RDBMS
Assume that we are given the following diagram
0,0 1 2 3 4 5 6 7 8

6. Introduction – Motivating Example
Our objective is to store this graph in a RDBMS and support queries on these simple geometries
What kind of relations we need?
Print names of rectangles which are squares
Find all objects which are inside the rectangle 7.
0,0 1 2 3 4 5 6 7 8

7. Introduction – Motivating Example
Relations
POINT(pname, x, y), EDGE(ename, aPoint), RECTANGLE(rname, anEdge).
POINT
RECTANGLE
EDGE p1 3 4 p2 10 p3 p4 r5 e1 e2 e3 e4 e1 p1 p2 e2 p3 e3 p4 e4
0,0 1 2 3 4 5 6 7 8

8. Introduction – Motivating Example
Logical Flow
Edge e1
Edge e2
E1.ename = e2.ename
E1.aPoint <> e2.aPoint
Edge_Pnt_List (eName, stPnt, endPnt)
Point p1
Point p2
Edge_length (eName, eLength)
Rectangle r
rname

9. Introduction – Motivating Example
CREATE VIEW pnt_list (ename, stPnt, endPnt)
AS SELECT e.ename, e1.aPoint, e2.aPoint
FROM edge e1, edge e2
WHERE e1.ename = e2.ename
AND e1.aPoint <> e2.aPoint;
CREATE VIEW edge_length (ename, elength)
AS SELECT e.ename, sqrt(sq(p1.x –p2.x) + sq(p1.y – p2.y)
FROM pnt_list e, point p1, point p2
WHERE e.stPnt = p1.pname
AND e.endPnt = p2.pname;

10. Introduction – Motivating Example
Discussion Question –
Print the square names

11. Introduction – Motivating Example
Solution
SELECT r.rname
FROM rectangle r, edge_length e
WHERE r.anEdge = e.ename
GROUP BY r.rname
HAVING max(e.elength) ~ MIN (e.elength);

12. Introduction
Though we can model and query these simple geometric objects, its
Not clean
Complexity increases with complex objects (like irregular polygons)
Even with these simple objects, how do you answer queries like ‘find nearest objects to point 2’ or ‘find all intersecting objects’
What is lacking
Support for complex data types
Support for predicates (e.g., area, intersect, length)

13. OODBMS-Fundamentals Has its origin in OO programming languages Object
State – current value
Behavior - what operations are permitted
Difference between PL Object and DB Object
PL – Objects exist only during program execution (transient objects).
DB – Objects persist beyond program termination; stored permanently on a secondary storage
DB – allows sharing of objects among multiple programs and applications

14. OODBMS-Fundamentals
OID – unique system generated object identifier for each object
Compare this with RDBMS primary key
Object structure
Arbitrarily complex in order to contain all necessary information about the object
Compare this with RDBMS
(rectangle object) – information about complex object is often scattered
The state of complex object may be constructed from other objects using type constructors

15. OODBMS-Fundamentals Type constructors
Basic – atom, tuple, and set
Others – list, bag, and array (collection/bulk types)
tuple – also called as a structured type
Formally an object can be thought of as a triple (I,C,V)
I – OID
C – type constructor
V – object state (current value)

16. OODBMS-Fundamentals Examples o1 = (i1, atom, ‘Pen-Chung Yew’)
o2 = (i2, atom, ‘Minneapolis’)
o3 = (i3, atom, ‘Computer Science’)
o4 = (i4, set, {i1,i2,i3})
o5 = (i4, tuple, <DNAME:i3, DCHAIR:i1>)

17. OODBMS-Fundamentals Type hierarchies and Inheritance Example
OODB permits definition of new types based on other predefined types, leading to a type hierarchy
Example
TYPE_NAME: function, function, …, function
PERSON: firstName, lastName, dob, SSN
STUDENT: firstName, lastName, dob, SSN, status, GPA
FACULTY: firstName, lastName, dob, SSN, rank, salary
STUDENT subtype_of PERSON: major, GPA
FACULTY subtype_of PERSON: rank, salary

18. OODBMS-Fundamentals
Exercise: Consider the geometry objects defined in our first example and defined class hierarchies
0,0 1 2 3 4 5 6 7 8

19. OODBMS-Fundamentals example -
GEOMETRY_OBJECT: Shape, Area, ReferencePoint
RECTANGLE subtype-of GEOMETRY_OBJECT (Shape=‘rectangle’): edge1, edge2, edge3, edge4

20. OODBMS-Fundamentals Standards: OOBMS ODMG Made up of several parts O2
Object Model
Object Definition Language (ODL)
Object Query Language (OQL)
Binding to OO programming languages (C++, Smalltalk, Java)
OOBMS O2
ObjectStore
Jasmine

21. Database Modeling
Enhance Entity Relationship (EER – Chap 4, Elmasri/Navathe)
Pictogram Enhanced Entity Relationship (PEER – Chapter 2, SD A Tour).
Unified Modeling Language (UML)
Object Definition Language

22. Database Modeling Example Let us start with EER
We use two examples (school-DB) and park-DB (from SDB-A Tour).
Identify typical objects (and hierarchies) in school-DB
Person, Student, Faculty, Department
Identify relationships
1:1, 1:M, M:N, partial participation, …
Let us start with EER
Includes all the modeling concepts of ER
Additionally includes oo concepts of – subclass, superclass, specialization and generalization, attribute and relationship inheritance

23. Database Modeling - EER
Person
SSN
firstName d
Student
Faculty
Department
major
worksin 1 N
status
rank
dob
lastName
code
name

24. Database Modeling - EER
Find a suitable entity and define a overlapping type of relationship

25. Database Modeling - UML
Person
SSN
dob
firstName
lastName
Department
Code
Name
Student
status
Faculty
rank *
{disjoint, mandatory}
dept
major 1
majorsIn
worksIn
0..1
chair
chairOf

26. Database Modeling - PEER
Exactly one
Many (0 or More)
Optional (0 or One)
One or More
Numerically Specified
Aggregation
Inheritance
Derived Class 1+
OGC-Geometry

27. Database Modeling - PEER
State Park (ER Model)
River
Road
Crosses
Name
Length
Geometry
NoOfLanes
supplies
Volume
Facility
Forest
Forest_Stand
Fire_Station
Fire_Image
Belongs_to
within
Elevation
access
Stand-id
Specie
Part_of
captures
manages
Image-id
Image 1 M N

28. Database Modeling - PEER
Pictogram : miniature version of geographic object inserted inside of a box
Entity pictograms
Relationship pictograms
Advantages
Ease of use
Complete grammar
Translation rules
Pictogram inserted ER diagram to SQL3 level constructs

29. Database Modeling - PEER
Pictograms
<Pictogram> <Shape>
* // any possible shape
! // user-defined shapes
<Shape> <Basic Shape>
<Multi-Shape>
<Derived Shape>
<Alternate Shape>

30. Database Modeling - PEER
<Basic Shape>
Polygon
Point
Line
Pictograms for Basic Shapes
Pictograms for Multi-Shapes
0, n n
<Cardinality>
0,1 1
1,n
0,n n

31. Database Modeling - PEER
Pictograms for Derived Shapes
Pictograms for Alternate Shapes
<Derived Shape>
<Basic Shape>
<Basic Shape>
<Basic Shape>
<Basic Shape>
<Derived Shape>

32. Database Modeling - PEER
Any Possible Shape * !
Raster
TIN
Thesian
Pictograms for Raster Shapes
Pictograms for Relationships
Part_of (Network)
Part_of (Partition)
User Defined Shape
Raster Shape
Raster
TIN
Thesian

33. Database Modeling - PEER
State Park (PEER)
River
Road
Crosses
Name
Length
NoOfLanes
supplies
Volume
Facility
Forest
Forest_Stand
Fire_Station
Fire_Image
Belongs_to
Elevation
access
Stand-id
Specie
Part_of
captures
manages
Image-id 1 N M

34. Summary and Conclusions
Learning Objectives
Understand OO Concepts
Conceptual Modeling
RDBMS limitations
No support for complex data types and predicates OO
Rich set of features – encapsulation, inheritance, ..
Helps manage complexity
Conceptual Modeling – Simple Extensions
EER, UML, PEER

35. Next Week
ORDMBS (SQL-3) in depth
Mapping of Conceptual Model onto ORDBMS (SQL-3 DDL constructs)
Examples using Postgresql/PostGIS
Comparison of OODBMS and ORDBMS
Conclusions

36. Additional Readings http://www.cs.umn.edu/~vatsavai/oo-ordbms.ppt
Main – Database Management Systems by Raghu Ramakrishnan (Chapter 24: Object Database Systems).
Additional References (relevant chapters):
Fundamentals of Database Systems – Elmasri & Navathe
A First Course In Database Systems – Ullman & Widom.
Spatial Database – A Tour (Chapter 2 and 3)