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Object Oriented & Object RelationalDatabases

Ranga Raju VatsavaiTeaching Mentor (Prof. Shekhar)

CSci 5708 : Architecture and Implementation of Database Management Systems, Fall 2003

Week 15 (11/24, 11/26/03) Lecture Notes



Outline for today11/24/03

Objectives Introduction

Need for OO/OR-DBMS

OO Fundamentals How (OO)DBMS incorporates OO ideas

Database Modeling/Querying

Conclusions

OODBMS ORDBMS

Conceptual ODL/UML EER/PEER



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 andORDBMS Conclusions



Learning Objectives

Basic concepts of OO and OR models Extensions at conceptual modeling

Mapping Conceptual Model into LogicalModel

Exposure to additional features in SQL:1999standard.

Ability to model and implement a broaderclass of applications (spatial, multimedia,engineering, biological, scientific, …)



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

34

5

6 7

8



Introduction – MotivatingExample

Our objective is to store this graph in aRDBMS and support queries on these simplegeometries 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

34

5

67

8



Introduction – Motivating Example

Relations POINT(pname, x, y), EDGE(ename, aPoint),

RECTANGLE(rname, anEdge).

0,

0

1

2

34

5

67

8

r5 e1

r5 e2

r5 e3

r5 e4

e1 p1

e1 p2

e2 p2

e2 p3

e3 p3

e3 p4

e4 p4

e4 p1

p1 3 4

p2 3 10

p3 10 10

p4 10 4

RECTANGLE

EDGEPOINT



Introduction – Motivating Example

Logical Flow

Edge e1 Edge e2

E1.ename = e2.enameE1.aPoint <> e2.aPoint

Edge_Pnt_List (eName, stPnt, endPnt)Point p1

Point p2

Edge_length (eName, eLength)

Rectangle r

rname




CREATE VIEW pnt_list (ename, stPnt, endPnt)

AS SELECT e.ename, e1.aPoint, e2.aPoint

FROM edge e1, edge e2WHERE 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;




Discussion Question –

Print the square names




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);



Introduction

Though we can model and query these simplegeometric objects, its Not clean

Complexity increases with complex objects (like irregularpolygons)

Even with these simple objects, how do you answer querieslike ‘find nearest objects to point 2’ or ‘find all intersectingobjects’

What is lacking Support for complex data types Support for predicates (e.g., area, intersect, length)



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



OODBMS-Fundamentals

OID – unique system generated objectidentifier 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 complexobject is often scattered

The state of complex object may be constructedfrom other objects using type constructors



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 atriple (I,C,V) I – OID C – type constructor V – object state (current value)



OODBMS-Fundamentals

Examples o

1= (i

1, atom, ‘Pen-Chung Yew’)

o2= (i

2, atom, ‘Minneapolis’)

o3= (i

3, atom, ‘Computer Science’)

o4= (i

4, set, {i

1,i

2,i

3})

o5= (i

4, tuple, <DNAME:i

3, DCHAIR:i

1>)



OODBMS-Fundamentals

Type hierarchies and Inheritance 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



OODBMS-Fundamentals

Exercise: Consider the geometry objectsdefined in our first example and definedclass hierarchies

0,0

1

2

34

5

6 7

8



OODBMS-Fundamentals

example - GEOMETRY_OBJECT: Shape, Area, ReferencePoint RECTANGLE subtype-of GEOMETRY_OBJECT

(Shape=‘rectangle’): edge1, edge2, edge3, edge4



OODBMS-Fundamentals

Standards: ODMG Made up of several parts

Object Model Object Definition Language (ODL) Object Query Language (OQL) Binding to OO programming languages (C++,

Smalltalk, Java)

OOBMS O2 ObjectStore Jasmine



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



Database Modeling

Example 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



Database Modeling - EER

PersonSSN firstNam

e

d

Student Faculty

Department

major worksin

1 1

NN

status rank

dob

lastName

code name



Database Modeling - EER

Find a suitable entity and define aoverlapping type of relationship



Database Modeling - UML

Person

SSN

dob

firstName

lastName

Department

Code

Name

Student

status

Faculty

rank

* *

{disjoint, mandatory}

deptmajor

1

1

majorsIn worksIn

0..1chair

chairOf



Database Modeling - PEERExactly one

Many (0 or More)

Optional (0 or One)

One or More

Numerically Specified

AggregationInheritance

Derived Class

1+

OGC-Geometry



Database Modeling - PEER

State Park (ER Model)

River RoadCrosses

Name Length Geometry Name NoOfLanes

Geometrysupplies

Volume

Facility Forest Forest_Stand

Fire_StationFire_Image

Name

Geometry

Belongs_to

within

Name

Elevation

accessGeometry

Stand-id

Geometry

Specie

Part_of

capturesmanages

Name Geometry Image-id Image

1 1

M1

N

MM

N

1 M

1

MM

N




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




Pictograms

<Pictogram> <Shape>

* // any possible shape

! // user-defined shapes

<Shape> <Basic Shape>

<Multi-Shape><Derived Shape>

<Alternate Shape>




<BasicShape> PolygonPoint Line

Pictograms for Basic Shapes

Pictograms for Multi-Shapes

0, nn

<Cardinality>

0,1

1

1,n

0,n

n




<Derived Shape>

Pictograms for Derived

Shapes

Pictograms for Alternate

Shapes

<Basic Shape>

<Basic Shape><Basic Shape>

<Basic Shape><Derived Shape>




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




State Park (PEER)

River RoadCrosses

Name Length Name NoOfLanes

supplies

Volume

Facility Forest Forest_Stand

Fire_Station Fire_Image

Name

Belongs_to

NameElevation

access

Stand-id Specie

Part_of

capturesmanages

Name Image-id

1 1

N

MM

N

1 M

1

MM

N



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



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



Additional Readings

http://www.cs.umn.edu/~vatsavai/oo-ordbms.ppt

Main – Database Management Systems byRaghu Ramakrishnan (Chapter 24: Object

Database Systems). Additional References (relevant chapters):

Fundamentals of Database Systems – Elmasri &Navathe

A First Course In Database Systems – Ullman & Widom. http://www-users.cs.umn.edu/~shekhar/5705/

Spatial Database – A Tour (Chapter 2 and 3)


http://www-users.cs.umn.edu/~shekhar/5705/

http://www-users.cs.umn.edu/~shekhar/5705/


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raju-ordbms