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ERROR: could not serialize access due to concurrent update

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PostgreSQL could not serialize access due to concurrent update

ERROR: could not serialize access due to concurrent update

PostgreSQL Could Not Serialize Access Due to Concurrent Update – Explained

When multiple transactions try to modify the same data at the same time under the SERIALIZABLE or REPEATABLE READ isolation level, PostgreSQL prevents conflicts to maintain data consistency.

You’ll see this error:

ERROR: could not serialize access due to concurrent update
Why This Happens

  • Two concurrent transactions are modifying the same row.

  • Using SERIALIZABLE or REPEATABLE READ isolation level.

  • Application retries or updates without checking locks.

  • Long-running transactions holding row locks.

Fixes for PostgreSQL Could Not Serialize Access Due to Concurrent Update
1. Retry the Transaction Automatically

Serialization failures are transient — just retry the transaction:

BEGIN;
-- your queries
COMMIT;
-- if fails, rollback and retry
2. Use a Lower Isolation Level (if safe)

Switch from SERIALIZABLE to READ COMMITTED:

SET TRANSACTION ISOLATION LEVEL READ COMMITTED;

Reduces conflicts in high-concurrency environments.

3. Reduce Transaction Scope

Keep transactions short and specific to minimize lock contention.

4. Use FOR UPDATE Locks

Lock rows before updating:

SELECT * FROM table_name WHERE id = 1 FOR UPDATE;

This ensures only one transaction can modify that row at a time.

5. Detect Conflicts in Application Logic

Handle retry logic in your app (e.g., using retry loops in Python, Java, etc.).

Conclusion

 At Learnomate Technologies, we’re here to support you every step of the way with top-notch training in PostgreSQL DBA and more.

For more detailed insights and tutorials, do check out our YouTube channel: www.youtube.com/@learnomate, where we regularly share practical tips and deep dives into essential database topics. And if you’re serious about mastering PostgreSQL DBA, head over to our website for our full training program: learnomate.org/training/postgresql-training/.

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ERROR: deadlock detected
PostgreSQL Performance Tuning