Why would a database ever allow a weaker isolation level than Serializable?
Serializable isolation — behaving as if every transaction ran one at a time — is the safest but the most expensive, since it requires the most locking or the most conflict detection. Weaker levels (Read Committed, Repeatable Read) allow more concurrency and higher throughput by tolerating specific, well-understood anomalies that many applications can live with, like non-repeatable reads.
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Database Transactions Explained: ACID, Isolation Levels, and Concurrency ControlWhat ACID actually guarantees, and how pessimistic vs optimistic concurrency control decide whether your app locks or retries under load.
Read the full analysisOther questions this article answers
- What does ACID actually stand for, and why do all four properties matter together?
- What's the practical difference between pessimistic and optimistic concurrency control?
- What is a race condition in a database transaction, and how does isolation prevent it?
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