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Object Oriented DB
Chapter Three
Traditional DB & Object Oriented DB
Dr. Ayman Mostafa
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Levels of Database
(1) Traditional DB & OODB
(2) Transaction Management & Concurrency Control
(3) Performance tuning & query optimization
(4) Distributed DBMS
(5) Big Data
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Agenda
1. Properties of Relational DB.
2. Features of Object Oriented DB.
3. Advantages of Object Oriented DB.
4. OODBMS and RDBMS Comparison.
5. Reasons of not using OODBMS publically.
6. Concurrency Control.
3
Agenda
1. Properties of Relational DB.
2. Features of Object Oriented DB.
3. Advantages of Object Oriented DB.
4. OODBMS and RDBMS Comparison.
5. Reasons of not using OODBMS publically.
6. Concurrency Control.
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1. Properties of Relational DB.
1) Values are atomic
2) Each row is unique.
3) Column values are of the same kind.
4) The sequence of columns is insignificant.
5) The sequence of rows is insignificant.
6) Each column has a unique name.
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Agenda
1. Properties of Relational DB.
2. Features of Object Oriented DB.
3. Advantages of Object Oriented DB.
4. OODBMS and RDBMS Comparison.
5. Reasons of not using OODBMS publically.
6. Concurrency Control.
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2. Features of Object Oriented DB
• Object oriented DB is the combination of object oriented
programming and persistent systems.
• The power of OODB comes from the treatment of both
persistent data ( as found in Database ) and transient
data ( as found in executing program ).
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2. Features of Object Oriented DB
• Objects are basically consist of the following:
1. Attributes – are data which defines the characteristics
of an object. This data may be simple such as integer,
strings, and real numbers or it may reference to a
complex object such as arrays.
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2. Features of Object Oriented DB
2. Methods – define the behavior of an object and are
what was formally called procedures or functions.
With traditional database, data manipulated by the
application is transient and data in the database is persisted
( stored in permanent storage in DB ). In object database,
the application can manipulate both transient and
persistent data.
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Agenda
1. Properties of Relational DB.
2. Features of Object Oriented DB.
3. Advantages of Object Oriented DB.
4. OODBMS and RDBMS Comparison.
5. Reasons of not using OODBMS publically.
6. Concurrency Control.
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3. Advantages of Object Oriented DB.
1. Capable to handle different types of data types.
2. Combination of OOP and database technology.
3. Improve Productivity.
4. Data Access.
5. Enriched modelling capabilities.
6. Extensibility.
7. Removal of impedance mismatch.
8. Support for schema evolution.
9. Applicability to Advanced database applications.
10. No primary keys.
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3. Advantages of Object Oriented DB.
1. Capable to handle different types of data types
An object oriented database can store any type of data
including text, numbers, pictures, video and voice.
2. Combination of OOP and database technology
The object oriented database technology combines object
oriented programming with the database technology to provide
an integrated application development system. There are many
advantages of including the definition of operations with the
definition of data.
First the operations which are defined are applied and are not
depending on the specific database application running at the
moment. Second the data types can be extended to support
complex data.
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3. Advantages of Object Oriented DB.
complex data types
Declaration
struct Account {
int account_number;
char *first_name;
char *last_name;
float balance;
};
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3. Advantages of Object Oriented DB.
3. Improve Productivity
• Inheritance allows programmers to develop solutions to
complex problems by defining the new objects in terms of
defined objects in the past. Polymorphism and dynamic
binding allows programmers to define operations for one
object and then to share the specification of the operation
with other object.
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3. Advantages of Object Oriented DB.
4. Data Access
• Object oriented databases represent relationships explicitly
supporting both navigational and associative access to
information.
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3. Advantages of Object Oriented DB.
5. Enriched modelling capabilities
The object oriented data mode allows the ‘real world’ to be
modeled more closely.
An object can store all relationships that it has with other
objects including many-to-many relationships and objects can
be formed into complex objects that the traditional data model
cannot cope with easily.
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3. Advantages of Object Oriented DB.
6. Extensibility
OODBMSs allow new data types to be built from existing data
types. The ability to factor out common properties of several
classes and form them into a super class that can be shared with
subclass can greatly reduce redundancy within system.
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3. Advantages of Object Oriented DB.
7. Removal of Impedance mismatch
A single language between Data Manipulation Language (DML)
and the programming language overcomes the Impedance
mismatch. This eliminates many of the efficiencies that occur in
mapping a declarative language such as SQL to an imperative
language ‘C’.
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3. Advantages of Object Oriented DB.
8. Support for schema evolution:
The tight coupling between data and applications in OODBMSs
makes schema evolution more feasible.
9. Applicability to advanced database applications
There are many areas where traditional DBMSs have not been
used, such as Computer Aided Design (CAD), Computer Aided
Software Engineering (CASE), Office Information System (OIS),
and Multimedia systems. The enriched modeling capabilities of
OODBMSs have made them suitable for these applications
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3. Advantages of Object Oriented DB.
10. No Primary Keys
In an OODBMS, the unique identification of objects is done behind
the scenes via OIDs and is completely invisible to the user.
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Agenda
1. Properties of Relational DB.
2. Features of Object Oriented DB.
3. Advantages of Object Oriented DB.
4. OODBMS and RDBMS Comparison.
5. Reasons of not using OODBMS publically.
6. Concurrency Control.
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4. OODBMS and RDBMS Comparison.
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4. OODBMS and RDBMS Comparison.
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Agenda
1. Properties of Relational DB.
2. Features of Object Oriented DB.
3. Advantages of Object Oriented DB.
4. OODBMS and RDBMS Comparison.
5. Reasons of not using OODBMS publically.
6. Concurrency Control.
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5. Reasons of not using OODBMS publically
1. Lack of Universal Data Model
There is no universally agreed Data Model for OODBMS and
most models lack of theoretical foundation. This disadvantage is
seen as significant drawback and is compared to pre-relational
system
2. Lack of Experience:
In comparison to RDBMSs the use of OODBMSs is relatively
limited. This means that we don’t have level of experience that
we have with traditional system.
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5. Reasons of not using OODBMS publically
3. Lack of Standards
There is a general lack of standards of OODBMS. There is no
standard Object Oriented Query Language.
4. People awareness about OODBMS
People are not aware about the Object Oriented Database and
therefore OOD had not been expanded into the business field.
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Summary
• Relational systems:
simple data types, powerful query languages, high
protection.
• Persistent programming language-based OODBs:
complex
data
types,
integration
with
programming
languages, high performance.
• Object-Relational systems:
complex data types, powerful query languages, high
protection.
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Agenda
1. Properties of Relational DB.
2. Features of Object Oriented DB.
3. Advantages of Object Oriented DB.
4. OODBMS and RDBMS Comparison.
5. Reasons of not using OODBMS publically.
6. Concurrency Control.
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6. Concurrency Control
 The objective of concurrency control is to ensure the
serializability of transactions in a multiuser database
environment.
 Concurrency control is important because the simultaneous
execution of transactions over a shared database can create
several data integrity and consistency problems.
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6. Concurrency Control
A. Lost updates
B. Uncommitted Data
C. Inconsistent Retrievals
D. Scheduler
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A. Lost updates
The lost update problem occurs when two concurrent
transactions, T1 and T2, are updating the same data
element and one of the updates is lost (overwritten by the
other transaction).
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A. Lost updates
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A. Lost updates
The addition of 100 units is “lost” during the process.
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B. Uncommitted Data
Uncommitted data occurs when two transactions, T1 and T2,
are executed concurrently and the first transaction (T1) is
rolled back after the second transaction (T2) has already
accessed the uncommitted data—thus violating the isolation
property of transactions.
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B. Uncommitted Data
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B. Uncommitted Data
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C. Inconsistent Retrievals
Inconsistent retrievals occur when a transaction accesses data
before and after another transaction(s) finish working with such
data.
For example, an inconsistent retrieval would occur if transaction
T1 calculates some summary (aggregate) function over a set of
data while another transaction (T2) is updating the same data.
The problem is that the transaction might read some data before
they are changed and other data after they are changed, thereby
yielding inconsistent results.
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C. Inconsistent Retrievals
1. T1 calculates the total quantity on hand of the products
stored in the PRODUCT table.
2. At the same time, T2 updates the quantity on hand
(PROD_QOH) for two of the PRODUCT table’s products.
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D. Scheduler
 The scheduler is a special DBMS process that establishes
the order in which the operations within concurrent
transactions are executed.
 The scheduler interleaves the execution of database
operations to ensure serializability and isolation of
transactions.
 To determine the appropriate order, the scheduler bases its
actions on concurrency control algorithms, such as locking
or time stamping methods.
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D. Scheduler
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