The Meaning of ACID
Transactions simplify error handling. If a sequence of writes fails halfway, the database rolls it back.
- Atomicity: "All or nothing". It's about abortability, not concurrency.
- Consistency: The database stays in a "good state" (invariants are met). This is actually a property of the application, relying on the database's A, I, and D.
- Isolation: Concurrently executing transactions don't interfere with each other. (Serializable isolation means they appear to run one after another).
- Durability: Once a transaction commits, it stays committed (even if power fails).
Knowledge Check
Which letter in ACID describes the ability to abort a transaction on error and discard partial writes?
Atomicity
Consistency
Isolation