Failures and recovery, Database Management System

Assignment Help:

Failures and Recovery

In practice various things might occur to prevent a transaction from completing. Recovery methods are used to bring database, which does not satisfy consistency needs, into a consistent state.  If a transaction finishes normally and commits then all the alters made by the transaction on the database are permanently registered in the database. They should not be lost. But, if a transaction does not finish normally and terminates abnormally then all the changes made by it should be discarded.  An abnormal termination of a transaction may be because of various causes, including:

a)  User may decide to terminate the transaction issued by him/ her

 b)  There may be a deadlock in the system

c)   There may be a system failure.

The recovery mechanisms must make sure that a consistent state of database can be restored under all circumstances.  In case of transaction terminate or deadlock, the system remains in control and can deal with the failure but in case of a system failure the system loses control because the computer itself has failed. Will the results of such type of failure be catastrophic? A database has a vast amount of useful information and any system failure should be recognised on the restart of the system. The DBMS should recover from some such failures.

 


Related Discussions:- Failures and recovery

Er-diagram, courier company er-diagram

courier company er-diagram

Determine set of minimal functional dependency-normalization, 1. Determine ...

1. Determine the set of minimal functional dependencies for the following data. The local bakery, Happy Cakes, needs your help designing a database that will support a kiosk in

Define deadlock term, a. Define the term "deadlock". There are four conditi...

a. Define the term "deadlock". There are four conditions that must hold before deadlock is possible. Name them. b. Outline an algorithm that detects whether there is a deadlock.

Define the unique constraints for the table client, Define the following co...

Define the following constraints for the table client. (i) BAL_DUE must be at least 1000. (ii) NAME is a unique key. (i)ALTER TABLE CLIENT ADD CONSTRAINT CLIENT_BAL_DUE_C1

Distributed Database query processing , I am doing research in this area, e...

I am doing research in this area, especially in sime join and join efficacy when several relations have been queried. Relations located in different sites. I need something like n

Hierarchical model is also known by, Hierarchical model is also known by? ...

Hierarchical model is also known by? A hierarchical model is also known as a Tree structure.

Process to find the non-concurrent objects, Process to find the non-concurr...

Process to find the non-concurrent objects Once we find out non-concurrent (mutually exclusive) objects, we can fold all objects together in one thread of process or control. O

A weak entity set and its identifying relationship, Q.  Define a weak entit...

Q.  Define a weak entity set and its identifying relationship. List the necessary conditions for a meaningful identifying relationship set of a weak entity set.    Entity is a t

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