Database manager, Database Management System

Database Manager

It is the interface among low-level data, queries and application programs. Databases typically need a large amount of storage space. It is kept on disks, as the main memory of computers has not store this information. Data is moved among disk storage and main memory as needed. Hence the movement of data to and from disk is slow relative to the speed of the control processing unit of computers; it is essential that database system structure data so as to decrease the need to move data between main memory and disk.

A database manager is a program module liable for interfacing with the database file system to the user questions. In addition, the tasks of enforcing constraints to keep the consistency and integrity of the data as well as its security are also done by database manager. Synchronising the concurrent operations performed by concurrent users is under the control of the data manager. It also done backup and recovery operations. Let us summarise now the vital responsibilities of Database manager.

  • Interaction with file manager: The raw data is kept on the disk using the file system which is usually given by a conventional operating system. The database manager changes the various DML statements into low-level file system commands. Therefore, the database manager is responsible for the real storing, retrieving and updating of data in the database.
  • Integrity enforcement: The data values stored in the database must assure certain types of consistency constraints. For instance, the balance of a bank account may never drop below a prescribed amount (for example, Rs. 1000/-). Likewise the number of holidays per year an employee may be having should not go over 8 days. These constraints must be specified explicitly by the DBA. If such constraints are given, then the database manager can check whether updates to the database result in the violation of any of these constraints and if so appropriate action may be imposed.
  • Security enforcement: As talk about above, not every user of the database wants to have access to the entire content of the database. It is the job of the database manager to enforce these security needs.
  • Backup and recovery: A computer system like any other electrical or mechanical device is subject to failure. There are a several of causes of such failure, including power failure, disk crash, and software errors. In each of these cases, information regarding the database is lost. It is the liability of database manager to detect such failures and restore the database to a state that existed prior to the occurrence of the failure. This is generally accomplished through the backup and recovery procedures.
  • Concurrency control: When various users update the database simultaneously, the consistency of data may no longer be preserved. It is required for the system to control the interaction between the concurrent users, and reaching such a control is one of the responsibilities of database manager.
Posted Date: 3/5/2013 5:15:05 AM | Location : United States







Related Discussions:- Database manager, Assignment Help, Ask Question on Database manager, Get Answer, Expert's Help, Database manager Discussions

Write discussion on Database manager
Your posts are moderated
Related Questions
Describes the several relationship constraints through giving suitable example? Constraints on relationships: There are two kinds of constraints on relationships. 1) Mapping

List two restrictions that are applied on the modification (updation, insertion or deletion) of base tables through view.  Ans: The two restrictions are: 1. If a view

Describe about Object oriented design Object oriented design is concerned with developing an object oriented model of a software system to implement known requirements. Many OO


1. Will you advise that your organization uses open source software and why? 2. Why is it important for business managers to have a basic understanding of the software development

Define a view and a trigger. Construct a view for the above relations that have the information about suppliers and the elements they supply. The view holds the S#, SNAME, P# , PNA

Explain the two types of participation constraint.  Total: The participation of an entity set E in a relationship set R is said to be total if each entity in E participates i

Ancestry database records information about family trees . Following information is recorded about each person: FIRSTNAME first name SURNAME surname MNAME maiden name (if


Problem 1. Write an assembly program to find the smallest among two numbers Writing an assembly program to find the smallest among two numbers 2. Explain the intern