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PostgreSQL · Concept

Isolation levels

PostgreSQL provides four standard isolation-level names but three distinct behaviors. Read committed is the default; serializable gives the strongest protection and may require transaction retries.

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Syntax

SET TRANSACTION ISOLATION LEVEL { READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE }

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  • SET TRANSACTION
  • Read Committed Isolation Level
  • Repeatable Read Isolation Level
  • Serializable Isolation Level
  • serialization failure
  • snapshot isolation

Source: PostgreSQL: Documentation: 18: 13.2. Transaction Isolation. Checked 2026-11-03.