Durability-transaction , Database Management System

Durability: This property necessitates that once a transaction has committed, the changes made by it be never lost because of subsequent failure. Thus, a transaction is also a basic unit of recovery.

A transaction has many states of implementation. These states are displayed in Figure.

                                        2117_Durability-transaction.png

                                                             Figure: States of transaction execution

A transaction is started as a program. From the initial state as the transaction is scheduled by the CPU it moves to the Implement state, though, in case of any system error at that point it may also be gone into the Abort state. During the implement transaction changes the data values and database gone to an inconsistent state. On successful completion of transaction it gone to the Commit state where the durability feature of transaction makes sure that the changes will not be lost. In case of any error the transaction moves to Rollback state where all the changes made by the transaction are not done. Therefore, after rollback or commit database is back into consistent state. In case a transaction has been rolled back, it is started as a latest transaction. All these states of the transaction are shown in above Figure.

Posted Date: 3/11/2013 5:23:42 AM | Location : United States







Related Discussions:- Durability-transaction , Assignment Help, Ask Question on Durability-transaction , Get Answer, Expert's Help, Durability-transaction Discussions

Write discussion on Durability-transaction
Your posts are moderated
Related Questions
Explain Domain calculus Domain calculus is one of the types of the relational calculus. The formal specification of the domain calculus was planned after the development of the

Develop a database broker framework to implement a persistence mechanism for the domain objects involved in the use case dealt with in Question 2.  a. Specify the attribute type

Differance between DDL and SDL? DDL and SDL - The data definition language (DDL) is used through DBA and database designers to describe internal schema, conceptual schema, and

What is the purpose of tables, private synonyms and public synonyms? If there are multiple objects of similar name on an Oracle database, that order are they accessed in? The r

Inheritance Adjustment As in object oriented analysis and design terms inheritance defines a relationship between classes, where as one class shares structure or behaviour def

Entity types that do not have any key attribute, and therefore cannot be identified independently, are known as weak entity types. A weak entity can be recognized uniquely only by

Multiple-mode locks : It offers two locks: exclusive locks and shared locks. But why do we require these two locks? There are a lot of transactions in the database system that neve

Differance between internal and external schema? Internal and external schema: Internal Schema • Describes the physical storage structure • Uses a physical data model External

A Relation Schema represented by R(A1, A2, ..., An) is made up of the relation name the list of attributes and R Ai that it contains. A relation is described as a set of tuples

Consider the following frequency counts of some itemsets in a transaction database r : freq({A}, r) = 0.405 freq({B}, r) = 0.510 freq({C}, r) = 0.303 freq({A