2. The Traditional Approach To Data
Management
– Create new
files for each
application
– Data
redundancy
– Data integrity
3. Disadvantages of File Processing
• Program-Data Dependence
– All programs maintain metadata for each file they
use
• Data Redundancy (Duplication of data)
– Different systems/programs have separate copies of
the same data
• Limited Data Sharing
– No centralized control of data
• Lengthy Development Times
– Programmers must design their own file formats
• Excessive Program Maintenance
– 80% of of information systems budget
5. Components of the
Database Environment
• CASE Tools – computer-aided software engineering
• Repository – centralized storehouse of metadata
• Database Management System (DBMS) – software
for managing the database
• Database – storehouse of the data
• Application Programs – software using the data
• User Interface – text and graphical displays to users
• Data Administrators – personnel responsible for
maintaining the database
• System Developers – personnel responsible for
designing databases and software
• End Users – people who use the applications and
databases
6. Disadvantages of DBMS
• Databases used in enterprises may involve additional
risks as compared to a conventional data processing
system in some areas
• Confidential, Privacy and Security : When
information is centralized and is made available to
users from remote locations, there is a possibility of
unauthorized users accessing sensitive information.
• It is necessary to take technical, administrative and
legal measures.
7. Disadvantages of DBMS
• Data Quality : Since database is accessible to users
remotely, adequate controls are needed to control users
updating data and to control data quality.
• With increased number of users accessing directly,
there is an opportunity for users to damage data.Unless
there are suitable controls, the data quality may be
compromised.
• Data Integrity : Since a large number of users cloud
be using a database concurrently, technical safeguards
are necessary to ensure that data remain correct during
operation.
9. Overall System Structure
• A database system is partitioned into
modules which handles different
responsibilities of over all system.
The functional components of a database
system are
Query processor Component
Storage manager component
10. Query Processor Component
• DML Compiler : It translates DML statements
into a lower level instructions that the query
evaluation engine understands
• Embedded DML precompiler : It converts DML
statements embedded in an application program
into normal procedure calls in the host language.
• DDL Interpreter : It interprets DDL statements
and records them in a set of tables
• Query evaluation engine : It executes lower level
instructions generated by the DML compiler
11. Storage manager component
• It is an Interface between the data stored in the database and
the application programs and queries submitted to the
system.
• Authorization and Integrity manager : It tests for
satisfaction of integrity constraints and checks the authority
of users to access data.
• Transaction Manager : It ensures concurrent transaction
executions processed without conflicting.
• File manager : It manages the allocation of space on disk
and the data structures used to represent information.
• Buffer manager : Which is responsible for fetching data
from disk storage into main memory.
12. Application Architectures
Two-tier architecture: E.g. client programs using ODBC/JDBC to
communicate with a database
Three-tier architecture: E.g. web-based applications, and
applications built using “middleware”
