Database manager, Database Management System

Assignment Help:

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.

Related Discussions:- Database manager

What is the used of specifying alias, What is the used of specifying alias?...

What is the used of specifying alias? Specifying alias: is used to rename column or attribute in a table.

The logical dbms architecture, Normal 0 false false false ...

Normal 0 false false false EN-IN X-NONE X-NONE

Describe application programming interface, Describe Application programmin...

Describe Application programming interface? Application Programming Interface - Commercial SQL implementations take one of the two primary techniques for involving SQL in a p

Using sql create a view rs for the relations r and s, Using SQL create a vi...

Using SQL create a view RS for the relations R and S. The view consists of the columns A and D renamed as X and Y in that order. Insert a tuple into it. Show the contents of t

What is disadvantages of dbms, What is Disadvantages Of DBMS ? 1. Cos...

What is Disadvantages Of DBMS ? 1. Cost of Software and Hardware and Migration - A important disadvantage of the DBMS system is cost. 2. Reduced Response and Throughpu

What is system r, What is System R? What are its two major subsystems? ...

What is System R? What are its two major subsystems? System R was intended and developed over a period of 1974-79 at IBM San Jose Research Center. It is a prototype and its pur

Where does view definition stored, Where does view definition stored? ...

Where does view definition stored? A view definition is permanently stored as part of the database.

Whenever the limit clause will be used, Whenever the LIMIT clause will be u...

Whenever the LIMIT clause will be used? LIMIT is used for the following kinds of problems: 1) Answering questions about first or last and largest or smallest 2) Splitting

How many types of data independence have, Types of data independence D...

Types of data independence Data independence can be classified into the following two types: Physical Data Independence: This means that for any change made in the physi

What is persistency, What is persistency? Persistency ensures which dat...

What is persistency? Persistency ensures which data is stored and that after the object is no longer available (program stops running) the data will be available to other users

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd