Jan 1, 2015

What is ACID Property or Properties of the Relational tables?

The ACID rules of transaction in any database ensure the reliability of data in all transactions in the database.


Atomicity shows the ability of database to assure that either all tasks of a transaction are performed or none of them. In other words database modifications must follow an all or nothing. Each transaction is said to be atomic if when one part of the transaction fails the entire transaction fails.


Consistency assure that database remain consistent state before the transaction and after the transaction is over.
For Example: An application transfer fund from one account to other account , the consistency property ensure that the total value of transaction should be same in both account at the start and end of transaction.  


Isolation assure that other operation can't be performed in an intermediate state during a transaction. As a result, transactions that run concurrently appear to be serialized.
For Example : DK Start transaction against the database at same time Singh issues the different transaction against same database, both transaction should operate on database in an isolated manner. The database perform DK's entire transaction or Singh's entire transaction but not together.


Durability  is responsible to notify the transaction is succeed, the transaction will persist, not undone. It will survive system failure and the database system has checked the integrity constraints and no need to abort the transaction.