ACID (A - Atomicity C - Consistency I - Isolation D - Durability)

ACID Properties

• Transaction processing must guarantee the consistency and recoverability of SQL Server databases.
• Ensures all transactions are performed as a single unit of work regardless of hardware or system failure.
• A – Atomicity C – Consistency I – Isolation D- Durability
  • Atomicity: Each transaction is treated as all or nothing – it either commits or aborts.
  • Consistency: ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct.  Consistency is honored even in the event of a system failure.
  • Isolation: separates concurrent transactions from the updates of other incomplete transactions. SQL Server accomplishes isolation among transactions by locking data or creating row versions.
  • Durability: After a transaction commits, the durability property ensures that the effects of the transaction persist even if a system failure occurs. If a system failure occurs while a transaction is in progress, the transaction is completely undone, leaving no partial effects on data.