ERROR: deadlock detected

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• 06 Oct, 2025
• 0 Comments
• 1 Min Read

ERROR: deadlock detected

Error Meaning:

This error means two or more transactions are waiting for each other’s locks, creating a circular wait. PostgreSQL detects this deadlock and aborts one transaction to break the cycle.

Common Causes:

• Concurrent updates or deletes on the same rows

• Improper transaction order

• Long-running transactions holding locks too long

• Missing indexes causing unnecessary locking

Solutions:

To fix a PostgreSQL deadlock detected error, ensure your application logic accesses tables in the same order, minimize long transactions, and enable detailed lock logging to identify conflict points.

• Keep transactions short – Commit as soon as possible.
• Access tables in a consistent order in all transactions.
• Avoid unnecessary locks — use SELECT ... FOR UPDATE only when needed.
• Use appropriate isolation levels (e.g., READ COMMITTED).
• Monitor locks using:

SELECT * FROM pg_locks;

Enable deadlock logging in postgresql.conf to trace problem queries:

log_lock_waits = on
deadlock_timeout = 1s

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Conclusion

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