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.
Answered in
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?
- What causes a deadlock, and how do databases resolve it?
More system design & architecture questions
- What does CodeDeploy RESTART actually deploy?
- Does CodeDeploy RESTART work with ECS or Lambda?
- Does RESTART remove an application from load-balancer traffic while it restarts?
- Does Elastic Beanstalk's Active Directory join require a domain password?
- Can an Elastic Beanstalk environment be healthy if the domain join fails?
- Will enabling Active Directory replace running instances?
- What is different about AWS Lambda Web Functions?
- Does Lambda Web Functions automatically cost less than ordinary Lambda?
Every answer on Crashtech is written by the editor of the article it comes from — never auto-summarised. Browse all answers or the System Design & Architecture beat.