Postgres: To identify blocking locks

 SELECT

blocked_locks.pid AS blocked_pid,
blocked_activity.usename AS blocked_user,
blocked_activity.query AS blocked_statement,
blocking_locks.pid AS blocking_pid,
blocking_activity.usename AS blocking_user,
blocking_activity.query AS blocking_statement
FROM pg_catalog.pg_locks AS blocked_locks
JOIN pg_catalog.pg_stat_activity AS blocked_activity ON blocked_activity.pid = blocked_locks.pid
JOIN pg_catalog.pg_locks AS blocking_locks ON blocking_locks.transactionid = blocked_locks.transactionid
AND blocking_locks.pid != blocked_locks.pid
JOIN pg_catalog.pg_stat_activity AS blocking_activity ON blocking_activity.pid = blocking_locks.pid
WHERE NOT blocked_locks.granted;