File Processing System

File Processing System:

File processing systems was an early attempt to computerize the manual filing system. A file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. Before DBMS was invented, Information was stored using File Processing System. In this System, data is stored in permanent system files (secondary Storage). Different application programs are written to extract data from these files and to add record to these files. File systems may use a storage device such as a hard disk or CD-ROM and involve maintaining the physical location of the files.

Here is the list of some important characteristics of file processing system:

§  It is a group of files storing data of an organization.

§  Each file is independent from one another.

§  Each file is called a flat file.

§  Each file contained and processed information for one specific function, such as accounting or inventory.

§  Files are designed by using programs written in programming languages such as COBOL, C, C++.

§   The physical implementation and access procedures are written into database application; therefore, physical changes resulted in intensive rework on the part of the programmer.

§  As systems became more complex, file processing systems offered little flexibility, presented many limitations, and were difficult to maintain.

Disadvantages of File System:

1. Data Redundancy and Inconsistency:

It is possible that the same information may be duplicated in different files. This results in data redundancy and inconsistency.

Consider following two data files:

Saving account data file: Stores information about customer. {acc_no, name, social_security, addr, teleph_no};

Checking account data file: Stores information about customer. {acc_no, name, social_security, addr, teleph_no};

Fields  {name, social_security, addr, teleph_no} are same in both the files i.e. Duplication of data is there which results data redundancy.

Data Redundancy increases the cost of storing & retrieving the data. Various copies of same data may contain different values then it results in Inconstancy of data. It may create a risk of out dated values of data.

For Example: If you change customer name in saving account data file then his name should be changed in all other files related to customer.

2. Difficulty in Accessing the Data:

File processing system doesn't allow needed data to be retrieved in a convenient and efficient manner. If a user wants information in a specific manner then he requires creating a program for it.

For Example, consider a data file, Saving account data file with fields {acc_no, name, social_security, addr, balance}. Application programs to access the data are written. But if user wants to display only those records for which balance is greater than Rs:10,000 and is that program is not written, then it’s difficult to access that data.

3. Data Isolation:

Because data are scattered in various files, and files may be in different formats, it is difficult to write new application programs to retrieve the appropriate data. If you want to extract data from two file then you are required to which part of the file is needed and how they are related to each other.

4. Integrity Problems:

A collection of data is integrated if it meets certain consistency constraints. A programmer always puts these constraints in the programs by adding some codes. In File Processing System, poor data integrity often arises and it becomes very difficult to add new constraints at that time.

For Example: The maximum marks of the student can never be more than 100.

5. Atomicity problem:

Atomicity is required to save the data values, it means that information is completely entered or canceled at all. Any system may fail at any time and at that time it is desired that data should be in a consistent state. A computer system is subject failure. In many applications, it is crucial to ensure that, once a failure has occurred and has been detected, the data are stored to the consistent state that existed prior to the failure. It is difficult to ensure this property in a conventional file-processing system.

For Example: If you are buying a ticket from railway and you are in the process of money transaction. Suddenly, your internet got disconnected then you may or may not have paid for the ticket. If you have paid then your ticket will be booked and if not then you will not be charged anything. That is called consistent state, means you have paid or not.

6. Concurrent-access anomalies:

If multiple users are updating the same data simultaneously it will result in inconsistent data state. In file processing system it is very difficult to handle this using program code. This results in concurrent access anomalies.

For example, a student wants to borrow a book from the library. He searches for the book in the library file and sees that only one copy is available. At the same time another student also, wants to borrow same book and checks that one copy available. First student opt for borrow and gets the book. But it is still not updated to zero copy in the file and the second student also opt for borrow! But there are no books available. This is the problem of concurrent access in the file system.

7. Security Problems:

Poor data security is the most threatening problem in File Processing System. There is very less security in File Processing System as anyone can easily modify and change the data stored in the files. All the users must have some restriction of accessing data up to a level.

For Example: If a student can access his data in the college library then he can easily change books issued date. Also he can change his fine detains to zero.

Comparison of File Management and DBMS:

-profshardulp.patil@gmail.com