ACID (Atomicity, Consistency, Isolation, Durability) is a set of database properties that makes sure that database transactions are processed reliably and completly. Relational databases makes sures that its transactions are completed propely as per ACID properties .
Database ACID Properties
Following sections explains about various database ACID properties:
Atomicity
In ACID properties, Atomicity requires that each and every transaction is fully completed and committed or nothing at all. If any one part of the current transaction fails, then the entire transaction fails, and the database state is left unchanged (databse is in its prior state).
The database system must guarantee the automacity in all situations such as power failure, database crashes and any other errors in the system.
Consistency
The consistency property ensures that any transaction will bring the database from one valid state to another. A transaction either creates a new and valid state of data, or, if any failure occurs, returns all data to its state before the transaction was started.
Any new data is being written to the database must be valid according to all defined rules, including constraints, cascades, etc.
Isolation
Isolation property ensures that any transaction which is in process and not yet committed must remain isolated from any other transaction.
In a database system, more than one transaction are being executed simultaneously and in parallel, the property of isolation states that all the transactions will be carried out and executed one after other.
Durability
Durability means that once a transaction has been committed, it will remain so, even in the event of power loss, crashes, or errors. Committed data is saved by the system.
Read:
- Types of Fact Tables in a Data Warehouse
- Data Warehouse Fact Constellation Schema and Design
- Types of Dimension Tables in a Data Warehouse
- Various Data Warehouse Design Approaches:Top-Down and Bottom-Up