Deadlock Detection and Prevention

-- Active lock waits
SELECT
  blocked.pid,
  blocked.query AS blocked_query,
  blocking.pid  AS blocking_pid,
  blocking.query AS blocking_query
FROM pg_stat_activity AS blocked
JOIN pg_stat_activity AS blocking
  ON blocking.pid = ANY(pg_blocking_pids(blocked.pid))
WHERE cardinality(pg_blocking_pids(blocked.pid)) > 0;

-- Kill a blocking query
SELECT pg_terminate_backend(42);