What Is File Processing System? Disadvantages of It.

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. But, There are Number of disadvantages in using File Processing System, to store the data.

1. Data Redundancy and Inconsistency :

Since the data files and application programs are created by different programmers over a long period.

• The data files are likely to have different  formats.
• program maybe written in several programming languages.
• same information may be duplicated in several places

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.

If the values of these common fields are not matching for some record in both files, then it results in Inconstancy of data.

2.Difficulty in Accessing The Data :

Conventional file processing system doesn't allow needed data to be retrieved in a convenient and efficient manner. 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 $10,000. And is that program is not written, then it ids 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.

4. Integrity Problems :

The data values stored in the database must satisfy certain types of consistency constraints. Application programmers enforce these consistency constraints by adding appropriate code in the various application programs, However, when a new constraint is to be added, it is difficult to change the program to enforce the new constraint.

5. Automicity problem :

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.

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.

7. Security Problems

Not every user of the database system should be able to access all the data. For example, in a banking system, payroll personnel need to see only that part of the database that has information about various bank employees. They do not need access to information about customer accounts. Since application programs are added to the system in ad hoc manner, it is difficult to enforce such security constraints.