Postgres "Deadlock Detected": Kill the Root Cause

Symptom

ERROR 40P01 deadlock detected; one transaction aborts.

Two transactions each hold a lock the other needs.

1. Read the DETAIL lines — they name both statementstail -100 /var/log/postgresql/*.log | grep -A4 deadlock

2. Touch rows in a consistent order everywhereUPDATE ... WHERE id IN (SELECT id FROM t ORDER BY id FOR UPDATE)

3. Keep transactions shortBEGIN late, COMMIT early; no user waits inside a txn

Lock ordering conventions + statement timeouts (lock_timeout 5s).

Spinning up a fresh box to reproduce or escape this error?

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