MySQL + SQL · Lesson 85
Transaction Isolation Levels in MySQL
What are Isolation Levels?
Isolation levels decide how much one transaction can see of other running transactions. Higher isolation = safer but slower.
The Four Levels
| Level | Allows |
|---|---|
| READ UNCOMMITTED | dirty reads (least safe) |
| READ COMMITTED | only committed data |
| REPEATABLE READ | same rows stay same (MySQL default) |
| SERIALIZABLE | full isolation (safest, slowest) |
Setting It
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;Summary
- Four levels: READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, SERIALIZABLE.
- InnoDB default is REPEATABLE READ. Higher = safer but slower.