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Disadvantages of file management system (file processing systems)

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Disadvantages of file management system (file processing systems)

  1. 1. Database Management System Name:- Raj Upadhyay Div.:- BX Roll. No.-58
  2. 2. Disadvantages of file management system (file processing systems)
  3. 3.  A file processing system is a collection of files and programs that access/modify these files. Typically, new files and programs are added over time (by different programmers) as new information needs to be stored and new ways to access information are needed. What is FPS?
  4. 4. When computers came, all the jobs become easy. But initial days, records were stored in the form of files. The way we stored in files is similar to papers, in the form of flat files – to be simpler, in notepad. Yes, the information's where all in the notepads with each fields of information separated by space, tab comma, semicolon or any other symbol
  5. 5. All the files were grouped based on their categories; file used to have only related information's and each file is named properly. As we can see in the above sample file has Student information. Student files for each class were bundled inside different folders to identify it quickly.
  6. 6. Now, if we want to see a specific Student detail from a file, what do we do? We know which file will have the data, we open that file and search for his details. Fine, here we see the files; we can open it and search for it. But imagine we want to display student details in a UI. Now how will we open a file, read or update it? There different programs like C, C++, COBOL etc. which helps to do this task. Using these programming languages, we can search for files, open them, search for the data inside them, and go to specific line in the file, add/update/delete specific information. File processing system is good when there is only limited number of files and data in are very less. As the data and files in the system grow, handling them becomes difficult.
  7. 7. Disadvantages of file system (file processing systems)
  8. 8. Data Redundancy It is possible that the same information may be duplicated in different files. This leads to data redundancy. Data redundancy results in memory wastage.
  9. 9.  For example consider that some customers have both kinds of accounts saving and current. In this case data about customers-name, address, email, contact-number will be duplicated in both files, file for saving accounts and file for current accounts. This leads to requirement of higher storage space. In other words, same information will be stored in two different locations (files). And, it wastes memory.
  10. 10. Data Inconsistency  Due to data redundancy, it is possible that data may not be in consistent state.  For example, consider that an address of some customer changes. And, that customer has both kinds of accounts. Now, it is possible that this changed address is updated in only one file, leaving address in other file as it is. As a result of this, same customer will have two different addresses in two different files, making data inconsistent.
  11. 11. Difficulty in Accessing Data  Accessing data is not convenient and efficient in file processing system.  Conventional file-processing environments do not allow needed data to be retrieved in a convenient and efficient manner. More responsive data-retrieval systems are required for general use.
  12. 12.  Suppose that one of the bank officer needs to find out the names of all customer who lives within a particular postal-code area. The officer asks the data-processing department to generate such a list. Because the designer of the original system did not anticipate this request there is no application program on hand to meet it . There is however an application program to generate the list of all customers. The bank officer has now two choices: either obtain the list of all customer and extract the needed information manually or ask a system programmer to write the necessary application program. Both alternatives are obviously unsatisfactory. Suppose that such program is written and that several days later, the same officer needs to trim that list to include only those customers who have an account balance of $10,000 or more. As expected, a program to generate such list does not exist. Again the officer has the preceding two options, neither of which is satisfactory.
  13. 13. Limited Data Sharing or Data isolation Data are scattered in various files. Different files may have different formats. And these files may be stored in different folders (directories) may be of different computers of different departments. So, due to this data isolation, it is difficult to share data among different applications.
  14. 14. Integrity Problems Data integrity means that the data contained in the database is both correct and consistent. For this purpose, the data stored in database must satisfy certain types of constraints (rules). For example, a balance for any account must not be less than zero. Such constraints are enforced in the system by adding appropriate code in application programs. But, when new constraints are added, such as balance should not be less than Rs. 5000, application programs need to be changed. But, it is not an easy task to change programs whenever required.
  15. 15. Atomicity Problems  Any operation on database must be atomic. This means, operation completes either 100% or 0%.  For example, a fund transfer from one account to another must happen in its entirely. But, computer systems are vulnerable to failure, such as system crash, virus attack. If a system failure occurs during the execution of fund transfer operation, it may possible that amount to be transferred, say Rs. 500, is debited from one account, but is not credited to another account.  This leaves database in inconsistent state. But, it is difficult to ensure atomicity in a file processing system.
  16. 16. Concurrent Access Anomalies  Multiple users are allowed to access data simultaneously (concurrently). This is for the sake of better performance and faster response.  Consider an operation to debit (withdrawal) an account. The program reads the old balance, calculates the new balance, and writes new balance back to database. Suppose an account has a balance of Rs. 5000. Now, a concurrent withdrawal of Rs. 1000 and Rs. 2000 may leave the balance Rs. 4000 or Rs. 3000 depending upon their completion time rather than the correct value of Rs. 2000.
  17. 17.  Here, concurrent data access should be allowed under some supervision.  But, due to lack of co-ordination among different application programs, this is not possible in file processing systems.
  18. 18. Security Problems Database should be accessible to users in a limited way. Each user should be allowed to access data concerning his application only. For example, a customer can check balance only for his/her own account. He She should not have access for information about other accounts. But in file processing system, application programs are added in an ad hoc manner by different programmers. So, it is difficult to enforce such kind of security constraints.