Software → Databases
Transaction Isolation
The degree to which concurrent transactions are prevented from interfering with each other.
Motivation
Transaction isolation solves the problem of deciding what one transaction is allowed to see while other transactions are running.
Where it fits
It belongs to database transactions and is one of the hardest parts of ACID to reason about in practice.
Mental model
Isolation is a visibility contract. Stronger isolation prevents more anomalies but can cost more concurrency.
Important details
Common levels include read committed, repeatable read, snapshot isolation, and serializable.
Common mistakes
- Assuming ACID always means serializable behavior.
- Ignoring isolation anomalies until production bugs appear.