/* Queries holding locks which other queries are waiting to be released */
SELECT
bl.pid AS blocked_pid, ka.query AS blocking_statement, now() - ka.query_start AS blocking_duration, kl.pid AS blocking_pid, a.query AS blocked_statement, now() - a.query_start AS blocked_duration
FROM
pg_catalog.pg_locks bl
JOIN
pg_catalog.pg_stat_activity a ON bl.pid = a.pid
JOIN
pg_catalog.pg_locks kl
JOIN
pg_catalog.pg_stat_activity ka ON kl.pid = ka.pid ON bl.transactionid = kl.transactionid AND bl.pid != kl.pid
WHERE
NOT bl.granted;