File based System

File-based systems were the manual based approached used for managing the files. It’s mainly the collection of application programs that used to provide services for the end-users. Each program was defined for a specific task and can’t be used simultaneously with each other.

File-based systems

However, there are many pitfalls of file based system.

Separation and isolation of data

When data is isolated in separate files, it is more difficult for us to access data that should be available. The application programmer is required to synchronize the processing of two or more files to ensure the correct data is extracted.

Duplication of data

With the use of the decentralized file-based approach, the uncontrolled duplication of data used to occur which can lead to loss of data integrity as well as is wasteful as it occupies unnecessary space in memory storage area.

Data dependence

Using file-based system, the physical structure and storage of the data files and records are defined in the application program code. This makes the file to be program-data dependent. If the user want to make any change in the existing structure it was a difficult a task and will lead to a modification of program. Such maintenance activities are time-consuming and subject to error.

Incompatible file formats

The structures of the file are dependent on the application programming language. However file structure provided in one programming language such as direct file, indexed-sequential file which is available in COBOL programming, may be different from the structure generated by other programming language such as C. The direct incompatibility makes them difficult to process jointly.

Fixed queries / proliferation of application programs

File-based systems are very dependent upon the application programmer. Any required queries or reports have to be written by the application programmer. Normally, a fixed format query or report can only be entertained and no facility for ad-hoc queries if offered.

Advantages of DBMSs

1. Control of data redundancy
2. Data consistency
3. More information from the same amount of data
4. Sharing of data
5. Improved data integrity
6. Improved security
7. Enforcement of standards
8. Economy of scale
9. Balance conflicting requirements
10. Improved data accessibility and responsiveness
11. Increased productivity
12. Improved maintenance through data independence
13. Increased concurrency
14. Improved backup and recovery services

Difference between file system and DBMS 

1. Both systems contain a collection of data and a set of programs which access that data. A database management system coordinates both the physical and the logical access to the data, whereas a file-processing system coordinates only the physical access.
2. A database management system reduces the amount of data duplication by ensuring that a physical piece of data is available to all programs authorized to have access to it, whereas data written by one program in a file-processing system may not be readable by another program.
3. A database management system is designed to allow flexible access to data (i.e., queries), whereas a file-processing system is designed to allow predetermined access to data (i.e., compiled programs).
4. A database management system is designed to coordinate multiple users accessing the same data at the same time. A file-processing system is usually designed to allow one or more programs to access different data files at the same time. In a file-processing system, a file can be accessed by two programs concurrently only if both programs have read-only access to the file.
5. Redundancy is control in DBMS, but not in file system.
6. Unauthorized access is restricted in DBMS but not in file system.
7. DBMS provide backup and recovery. When data is lost in file system then it not recover.
8. DBMS provide multiple user interfaces. Data is isolated in file system.

Disadvantages of database approach

The Database approach too has some disadvantages. They are:

Complexity:

Database management system is an extremely complex piece of software. The users must be familiar with its functionality in-order to make full use of it. Therefore, training for the administrators, designers and users is required.

Size

The database management system consumes a substantial amount of main memory as well as a large amount of disk space in order to make it run efficiently.

Cost of DBMS

A multi-user database management system may be very expensive. Even after the installation, there is a high recurrent annual maintenance cost on the software.

Cost of conversion

When moving from a file-base system to a database system, the company is required to have additional expenses on hardware acquisition and training cost.

Performance

As the database approach is to manage many applications rather than exclusively for a particular one, some applications may not run as fast as before.

Higher impact of a failure

The database approach increases the vulnerability of the system due to the centralization. As all users and applications reply on the database availability, the failure of any component can bring operations to a halt and affect the services to the customer seriously.