What transaction isolation levels are available in SQL (PostgreSQL)?
sobes.tech AI
Answer from AI
PostgreSQL has four standard transaction isolation levels:
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Read Uncommitted — the lowest level, allows reading uncommitted data (dirty reads). In PostgreSQL, it effectively behaves like Read Committed.
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Read Committed — the default. A transaction sees only data committed before each query. Non-repeatable reads are possible.
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Repeatable Read — the transaction sees data as it was at the start of the transaction. Guarantees repeatable reads but phantom reads can occur.
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Serializable — the strictest level. Transactions execute as if sequential, preventing phantom reads and ensuring full isolation.
The choice of level depends on requirements for consistency and performance. For example, Serializable provides maximum integrity but may reduce concurrency.