Friday, April 15, 2011

Advantages of Conventional or Centralized DBMS

Following are the main advantages of Conventional or Centralized Database management system (DBMS):
  1. Redundancy can be reduced: As we know that in non-database systems (file oriented systems) each application has its ow11 private files, because of which there exists considerable redundancy in stored data, resulting in wastage of storage space.Although database systems try to eliminate all possible redundancy, but we do not mean to suggest that all redundancy can be eliminated or necessarily should be eliminated. Sometimes there is sound business or technical reasons for maintaining several distinct copies of the same stored data. However, we do mean to suggest that any such redundancy should be carefully controlled i.e., the DBMS should be aware of it, if it exists, and should assume responsibility for "propagating updates".
  2. Inconsistency can be avoided to some extent: Let 11s assume that in EMPLOYEE database, there exist two entries for the employee "ABC". This duplication is not only leads to redundancy but also leads to inconsistency as only one value of "ABC" might change during any modification of the data, hence two values in the database will not agree with each other. Clearly a database that is in an inconsistent state will supply incorrect or contradictory information to its users. It should be clearly noted that if the given fact is represented by a single entry, then such inconsistency can be avoided. Alternatively, if the redundancy is not removed but is controlled, then the DBMS could guarantee that the database is never inconsistent.
  3. The data can be shared: With DBMS it is possible to share data in the database among various applications and also it is possible to satisfy the data requirements of new applications without having to create any additional stored data.
  4. Standards can be enforced: With central control of database, the DBA (Database Administrator) can ensure that the data represents all applicable standards like corporate, installation, departmental, industry, national and international standards etc
  5. Security restrictions can be applied: A DBA can ensure that the database is accessed only through proper channels and by authorized users. For this purpose DBA defines some security rules, which are checked whenever there is an attempt to access the sensitive data.
  6. Integrity can be maintained: The problem of integrity is the problem of ensuring that the data in the database is accurate and correct. Centralized control of DBMS call help in avoiding the problems of inconsistency as explained in the 2nd point, by permitting the DBA to define integrity rules to be checked whenever any data update, delete or insert operation is attempted.
  7. Conflicting requirements can be balanced: Knowing the overall requirements of the enterprise - as opposed to the requirements of individual users - the DBA can so structure the system as to provide an overall service that is "best for the enterprise". For example, a representation can be chose11 for the data in storage that gives fast access for the most important applications.

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