ACID Properties

Transaction processing guarantees the consistency and recoverability of a database ensuring that all transactions are performed as a single unit of work even in the presence of logical or physical failure. Such transactions are said to have ACID properties, here are the common definitions of these four ACID properties.

Atomicity:
Atomicity means that each transaction si treated as all or nothing, it either commits or aborts; if it commits the effects remain, if it aborts then all the effects are undone.

Consistency:
The consistency property ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct. Constraints and rules are honored even in the event of system failure.

Isolation:
Isolation separates concurrent transactions from the updates of other incomplete transactions.

Durability:
After a transaction commits the effects of the transaction must persist even if system failure occurs. If a system failure occurs while a transaction is in progress the transaction is completely undone, leaving no partial effects on the data.