[Fix PostgreSQL Table Locks] #sql #postgresql

blocked_blocking.sql

-- The following query may be helpful to see what processes or applications are
-- blocking SQL statements (these only find row-level locks, not object-level locks).
SELECT blocked_locks.pid                    AS blocked_pid,
       blocked_activity.usename             AS blocked_user,
       blocking_locks.pid                   AS blocking_pid,
       blocking_activity.usename            AS blocking_user,
       blocked_activity.query               AS blocked_statement,
       blocking_activity.query              AS current_statement_in_blocking_process,
       blocked_activity.application_name    AS blocked_application,
       blocking_activity.application_name   AS blocking_application
  FROM pg_catalog.pg_locks                  blocked_locks
  JOIN pg_catalog.pg_stat_activity          blocked_activity
       ON blocked_activity.pid = blocked_locks.pid
  JOIN pg_catalog.pg_locks                  blocking_locks 
       ON blocking_locks.locktype = blocked_locks.locktype
       AND blocking_locks.DATABASE IS NOT DISTINCT FROM blocked_locks.DATABASE
       AND blocking_locks.relation IS NOT DISTINCT FROM blocked_locks.relation
       AND blocking_locks.page IS NOT DISTINCT FROM blocked_locks.page
       AND blocking_locks.tuple IS NOT DISTINCT FROM blocked_locks.tuple
       AND blocking_locks.virtualxid IS NOT DISTINCT FROM blocked_locks.virtualxid
       AND blocking_locks.transactionid IS NOT DISTINCT FROM blocked_locks.transactionid
       AND blocking_locks.classid IS NOT DISTINCT FROM blocked_locks.classid
       AND blocking_locks.objid IS NOT DISTINCT FROM blocked_locks.objid
       AND blocking_locks.objsubid IS NOT DISTINCT FROM blocked_locks.objsubid
       AND blocking_locks.pid != blocked_locks.pid
 
  JOIN pg_catalog.pg_stat_activity blocking_activity
       ON blocking_activity.pid = blocking_locks.pid
   WHERE NOT blocked_locks.GRANTED;

pg_locks_view.sql

-- Looking at pg_locks shows you what locks are granted and what
-- processes are waiting for locks to be acquired. A good query
-- to start looking for lock problems: 
SELECT relation::regclass, *
  FROM pg_locks
 WHERE NOT GRANTED;

terminate.sql

-- What are the running processes
SELECT * FROM pg_stat_activity WHERE state = 'active' ORDER BY query_start;

-- Cancel process
SELECT pg_cancel_backend(<pid of the process>);

-- Kill process
SELECT pg_terminate_backend(<pid of the process>);