Database Recovery And Security
In this part we will introduce two main issues relating to database management systems.
A computer system suffers from dissimilar types of failures. A DBMS controls very critical data of an organisation and thus must be reliable. Though, the reliability of the database system is related to the reliability of the computer system on which it runs. In this part we will talk about recovery of the data having in a database system following failure of several types and present the dissimilar approaches to database recovery. The types of failures that the computer system is likely to be subjected to contain failures of components or subsystems, power outages, software failures, accidents, unforeseen situations and natural or man-made disasters. Database recovery methods are techniques of making the database consistent till the last possible consistent state. The aim of recovery scheme is to permit database operations to be resumed after a failure with minimum loss of information at an economically justifiable cost.
The second important issue that is being discussed in this unit is Database security. "Database security" is protection of the information included in the database against unauthorised access, destruction or modification. The first condition for security is to have Database integrity. "Database integrity" is the mechanism that is applied to ensure that the data in the database is consistent.