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 are uncommitted modifications, What are uncommitted modifications? ...

What are uncommitted modifications? The immediate-modification technique permits database modifications to be output to the database whereas the transaction is still in the act

Characteristics, what are the main characteristics of database

what are the main characteristics of database

Complete replication-data replication, Complete replication: It implies ma...

Complete replication: It implies maintaining of a whole copy of the database at every site. Thus, the reliability & availability and performance for query response are maximized.

What are the properties of transaction, What are the properties of transact...

What are the properties of transaction? There are three properties of transactions :- A)     Atomicity B)      Consistency C)       Isolation

Need senior oracle database administrator, Project Description: Oracle C...

Project Description: Oracle Certified Professional with 20 years of practice, Oracle version 6.0.34, 7.3, 8.0, 8i, 9i, 10G, 11G, 12C. Crossplatform migration, Informix, MSSql

Main difference between read-only and update methods, What is the main diff...

What is the main difference between read-only and update methods? A read-only method does not affect the values of a variable in an object, whereas an update method may alter t

Nested relational model, what is Nested relational model? Explain with exam...

what is Nested relational model? Explain with examples.

Related Rates, All edges of a cube are expanding at a rate of 6 centimeters...

All edges of a cube are expanding at a rate of 6 centimeters per second. How fast is the surface area changing when each edge is (a) 2 centimeters and (b) 10 centimeters?

Describe hashing in dbms, Describe Hashing in DBMS? Hashing: Hashing ...

Describe Hashing in DBMS? Hashing: Hashing is a technique to store data within an array so which storing, searching, inserting and deleting data is fast (in theory it's O(1))

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