Bom pessoal, segue abaixo consulta para monitorar os locks(Bloqueios de Tabelas e Registros) existentes no seu Banco de Dados PostgreSQL:
SELECT bl.pid AS blocked_pid,
a.usename AS blocked_user,
ka.current_query AS blocking_statement,
now() - ka.query_start AS blocking_duration,
kl.pid AS blocking_pid,
ka.usename AS blocking_user,
a.current_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 a.procpid = bl.pid
JOIN pg_catalog.pg_locks kl ON kl.transactionid = bl.transactionid AND kl.pid != bl.pid
JOIN pg_catalog.pg_stat_activity ka ON ka.procpid = kl.pid
WHERE NOT bl.granted;
For PostgreSQL >= 9.2:
SELECT bl.pid AS blocked_pid,
a.usename AS blocked_user,
ka.query AS blocking_statement,
now() - ka.query_start AS blocking_duration,
kl.pid AS blocking_pid,
ka.usename AS blocking_user,
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 a.pid = bl.pid
JOIN pg_catalog.pg_locks kl ON kl.transactionid = bl.transactionid AND kl.pid != bl.pid
JOIN pg_catalog.pg_stat_activity ka ON ka.pid = kl.pid
WHERE NOT bl.granted;