src/test/isolation2/expected/resource_queue_cancel.out

-- Simple test for cancellation of a query stuck on a resource queue when the
-- active statements limit is reached.

0:CREATE RESOURCE QUEUE rq_cancel WITH (active_statements = 1);
CREATE
0:CREATE ROLE role_cancel RESOURCE QUEUE rq_cancel;
CREATE

-- Consume an active statement in session 1.
1:SET ROLE role_cancel;
SET
1:BEGIN;
BEGIN
1:DECLARE c CURSOR FOR SELECT 0;
DECLARE

-- Make session 2 wait on the resource queue lock.
2:SET ROLE role_cancel;
SET
2&:SELECT 100;  <waiting ...>

-- Cancel SELECT from session 2.
0:SELECT pg_cancel_backend(pid) FROM pg_stat_activity WHERE query='SELECT 100;';
 pg_cancel_backend 
-------------------
 t                 
(1 row)

-- Now once we end session 1's transaction, we should be able to consume the
-- vacated active statement slot in session 2.
1:END;
END

2<:  <... completed>
ERROR:  canceling statement due to user request
2:END;
END
2:BEGIN;
BEGIN
2:DECLARE c CURSOR FOR SELECT 0;
DECLARE

2:END;
END

-- Sanity check: Ensure that the resource queue is now empty.
0:SELECT rsqcountlimit, rsqcountvalue FROM pg_resqueue_status WHERE rsqname = 'rq_cancel';
 rsqcountlimit | rsqcountvalue 
---------------+---------------
 1             | 0             
(1 row)

-- Cleanup
0:DROP ROLE role_cancel;
DROP
0:DROP RESOURCE QUEUE rq_cancel;
DROP