File Based System and Its Limitations
File based systems are an early attempt to computerize the manual filing system. For example, a manual file can be set up to hold all the correspondence relating to a particular matter as a product, task, or employee.
The manual filing system works well when the number of items to be stored is small. It even works quite well when the number of items stored is quite large and they are only needed to be stored and retrieved.
For retrieval of information, the entries could be searched sequentially. Alternatively, an indexing system could be used to locate the information.
Limitations of File Based System
Separation and isolation of data:
When the data is stored in separate files it becomes difficult to access. It becomes extremely complex when the data has to be retrieved from more than two files as a large amount of data has to be searched.
Duplication of data:
Due to the decentralized approach, the file system leads to uncontrolled duplication of data. This is undesirable as the duplication leads to wastage of a lot of storage space. It also costs time and money to enter the data more than once.
The data in a file system can become inconsistent if more than one person modifies the data concurrently. Entering wrong data is also another reason for inconsistencies.
The physical structure and storage of data files and records are defined in the application code. This means that it is extremely difficult to make changes to the existing structure. The programmer would have to identify all the affected programs, modify them and retest them. This characteristic of the File Based system is called program data dependence.
File Formats: Since the structure of the files is embedded in application programs, the structure is dependent on application programming languages. Hence the structure of a file generated by COBOL programming language may be quite different from a file generated by ‘C’ programming language. This incompatibility makes them difficult to process jointly. The application developer may have to develop software to convert the files to some common format for processing. However, this may be time consuming and expensive.
File based systems are very much dependent on application programs. Any query or report needed by the organization has to be developed by the application programmer. With time, the type and number of queries or reports increases. Producing different types of queries or reports is not possible in File Based Systems. As a result, in some organisations the type of queries or reports to be produced is fixed. No new query or report of the data could be generated.