What is ACID?
ACID stands for Atomicity, Consistency, Isolation, and Durability — four key properties that guarantee reliable processing of database transactions.
The Four Properties
Atomicity
A transaction is treated as a single, indivisible unit. Either all operations complete successfully, or none are applied.
Consistency
A transaction brings the database from one valid state to another. All data must satisfy defined rules and constraints.
Isolation
Concurrent transactions execute as if they were running sequentially. Intermediate states are invisible to other transactions.
Durability
Once a transaction is committed, its changes persist even in the event of a system failure.
Why ACID Matters
- Data Integrity: Ensures accuracy and reliability
- Predictability: Transactions behave consistently
- Recovery: Easy to recover from failures
- Concurrency: Safe simultaneous access