What level of transaction isolation do you use in PostgreSQL to ensure data integrity?

In PostgreSQL, the default transaction isolation level is Read Committed. This level guarantees that a transaction only sees committed data, preventing dirty reads.

For stricter isolation, such as preventing non-repeatable reads or phantom reads, Repeatable Read or Serializable levels can be used:

• Repeatable Read — a transaction sees data in the state it was at the start.
• Serializable — the strictest level, ensuring full transaction isolation as if they were executed sequentially.

The choice depends on data integrity and performance requirements. Usually, Read Committed suffices, but for critical operations, higher levels should be considered.