Purpose of Database System

Purpose of Database System

AU: May-07, 12, Dec.-04, Marks 8

• Earlier database systems are created in response to manage the commercial data. These data is typically stored in files. To allow users to manipulate these files various programs are written for

1) Addition of new data

2) Updating the data

3) Deleting the data.

• As per the addition of new need, separate application programs were required to write. Thus as the time goes by, the system acquires more files and more application programs.

• This typical file processing system is supported by conventional operating system. Thus the file processing system can be described as -

• The system that stores the permanent records in files and it needs different application programs to extract or add the records.

Before introducing database management system, this file processing system was in use. However, such a system has many drawbacks. Let us discuss them

Disadvantages of Traditional File Processing System

The traditional file system has following disadvantages:

1) Data redundancy: Data redundancy means duplication of data at several places. Since different programmers create different files and these files might have different structures, there are chances that some information may appear repeatedly in some or more format at several places.

2) Data inconsistency: Data inconsistency occurs when various copies of same data may no longer get matched. For example changed address of an employee may be reflected in one department and may not be available (or old address present) for other department.

3) Difficulty in accessing data: The conventional file system does not allow to retrieve the desired data in efficient and convenient manner.

4) Data isolation: As the data is scattered over several files and files may be in different formats, it becomes to retrieve the desired data from the file for writing the new application.

5) Integrity problems: Data integrity means data values entered in the database fall within a specified range and are of correct format. With the use of several files enforcing such constraint on the data becomes difficult.

6) Atomicity problems: An atomicity means particular operation must be carried out sib entirely or not at all with the database. It is difficult to ensure atomicity in conventional file processing system.

7) Concurrent access anomalies: For efficient execution, multiple users update data simultaneously, in such a case data need to be synchronized. As in traditional file systems, data is distributed over multiple files, one cannot access these files concurrently.

8) Security problems: Every user is not allowed to access all the data of database no system. Since application program in file system are added in an ad hoc manner, enforcing such security constraints become difficult.

Database systems offer solutions to all the above mentioned problems.

Difference between Database System and Conventional File System

Characteristics of Database Systems

Following are the characteristics of database system

1) Representation of some aspects of real world applications.

2) Systematic management of information.

3) Representing the data by multiple views.

4) Efficient and easy implementation of various operations such as insertion,deletion and updation.

5) It maintains data for some specific purpose.

6) It represents logical relationship between records and data.

Advantages of Database Systems

Following are the advantages of DBMS -

1) DBMS removes the data redundancy that means there is no duplication of data in database, ends it

2) DBMS allows to retrieve the desired data in required format.

3) Data can be isolated in separate tables for convenient and efficient use.

4) Data can be accessed efficiently using a simple query language.

5) The data integrity can be maintained. That means - the constraints can be applied on data and it should be in some specific range.

6) The atomicity of data can be maintained. That means, if some operation is performed on one particular table of the database, then the change must be reflected for the entire database.

 7) The DBMS allows concurrent access to multiple users by using the synchronization technique.

8) The security policies can be applied to DBMS to allow the user to access only desired part of the database system.

Disadvantages of Database Systems          

1) Complex design: Database design is complex, difficult and time consuming.

2) Hardware and software cost: Large amount of investment is needed to setup the required hardware or to repair software failure.

3) Damaged part: If one part of database is corrupted or damaged, then entire database may get affected.

4) Conversion cost: If the current system is in conventional file system and if we need to convert it to database systems then large amount of cost is incurred in purchasing different tools, and adopting different techniques as per the requirement.

5) Training: For designing and maintaining the database systems, the people need to be trained.

Review Questions

1. Compare file system with database system. AU: May-07, Marks 8, May-12, Marks 2

2.What are the advantages and disadvantages of DBMS?