CREATE SCHEMA shared_connection_stats;
SET search_path TO shared_connection_stats;
-- set the cached connections to zero
-- and execute a distributed query so that
-- we end up with zero cached connections afterwards
ALTER SYSTEM SET citus.max_cached_conns_per_worker TO 0;
SELECT pg_reload_conf();
 pg_reload_conf
---------------------------------------------------------------------
 t
(1 row)

-- disable deadlock detection and re-trigger 2PC recovery
-- once more when citus.max_cached_conns_per_worker is zero
-- so that we can be sure that the connections established for
-- maintanince daemon is closed properly.
-- this is to prevent random failures in the tests (otherwise, we
-- might see connections established for this operations)
ALTER SYSTEM SET citus.distributed_deadlock_detection_factor TO -1;
ALTER SYSTEM SET citus.recover_2pc_interval TO '1ms';
SELECT pg_reload_conf();
 pg_reload_conf
---------------------------------------------------------------------
 t
(1 row)

SELECT pg_sleep(0.1);
 pg_sleep
---------------------------------------------------------------------

(1 row)

-- now that last 2PC recovery is done, we're good to disable it
ALTER SYSTEM SET citus.recover_2pc_interval TO '1h';
SELECT pg_reload_conf();
 pg_reload_conf
---------------------------------------------------------------------
 t
(1 row)

SET citus.shard_count TO 32;
SET citus.shard_replication_factor TO 1;
CREATE TABLE test (a int);
SELECT create_distributed_table('test', 'a');
 create_distributed_table
---------------------------------------------------------------------

(1 row)

INSERT INTO test SELECT i FROM generate_series(0,100)i;
-- show that no connections are cached
SELECT
	connection_count_to_node
FROM
	citus_remote_connection_stats()
WHERE
	port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
	database_name = 'regression'
ORDER BY
	hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        0
                        0
(2 rows)

-- single shard queries require single connection per node
BEGIN;
	SELECT count(*) FROM test WHERE a = 1;
 count
---------------------------------------------------------------------
     1
(1 row)

	SELECT count(*) FROM test WHERE a = 2;
 count
---------------------------------------------------------------------
     1
(1 row)

	SELECT
		connection_count_to_node
	FROM
		citus_remote_connection_stats()
	WHERE
		port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
		database_name = 'regression'
	ORDER BY
		hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        1
                        1
(2 rows)

COMMIT;
-- show that no connections are cached
SELECT
	connection_count_to_node
FROM
	citus_remote_connection_stats()
WHERE
	port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
	database_name = 'regression'
ORDER BY
	hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        0
                        0
(2 rows)

-- executor is only allowed to establish a single connection per node
BEGIN;
	SET LOCAL citus.max_adaptive_executor_pool_size TO 1;
	SELECT count(*) FROM test;
 count
---------------------------------------------------------------------
   101
(1 row)

	SELECT
		connection_count_to_node
	FROM
		citus_remote_connection_stats()
	WHERE
		port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
		database_name = 'regression'
	ORDER BY
		hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        1
                        1
(2 rows)

COMMIT;
-- show that no connections are cached
SELECT
	connection_count_to_node
FROM
	citus_remote_connection_stats()
WHERE
	port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
	database_name = 'regression'
ORDER BY
	hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        0
                        0
(2 rows)

-- sequential mode is allowed to establish a single connection per node
BEGIN;
	SET LOCAL citus.multi_shard_modify_mode TO 'sequential';
	SELECT count(*) FROM test;
 count
---------------------------------------------------------------------
   101
(1 row)

	SELECT
		connection_count_to_node
	FROM
		citus_remote_connection_stats()
	WHERE
		port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
		database_name = 'regression'
	ORDER BY
		hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        1
                        1
(2 rows)

COMMIT;
-- show that no connections are cached
SELECT
	connection_count_to_node
FROM
	citus_remote_connection_stats()
WHERE
	port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
	database_name = 'regression'
ORDER BY
	hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        0
                        0
(2 rows)

-- now, decrease the shared pool size, and prevent
-- establishing all the required connections
ALTER SYSTEM SET citus.max_shared_pool_size TO 5;
SELECT pg_reload_conf();
 pg_reload_conf
---------------------------------------------------------------------
 t
(1 row)

SELECT pg_sleep(0.1);
 pg_sleep
---------------------------------------------------------------------

(1 row)

BEGIN;
	SET LOCAL citus.node_connection_timeout TO 1000;
	SET LOCAL citus.connection_retry_timeout TO 2000;
	SET LOCAL citus.force_max_query_parallelization TO ON;
	SELECT count(*) FROM test;
ERROR:  citus.max_shared_pool_size number of connections are already established to the node localhost:xxxxx,so cannot establish any more connections
HINT:  consider increasing citus.max_shared_pool_size or citus.connection_retry_timeout
COMMIT;
-- pg_sleep forces almost 1 connection per placement
-- now, some of the optional connections would be skipped,
-- and only 5 connections are used per node
BEGIN;
	SELECT count(*), pg_sleep(0.1) FROM test;
 count | pg_sleep
---------------------------------------------------------------------
   101 |
(1 row)

	SELECT
		connection_count_to_node
	FROM
		citus_remote_connection_stats()
	WHERE
		port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
		database_name = 'regression'
	ORDER BY
		hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                        5
                        5
(2 rows)

COMMIT;
SHOW citus.max_shared_pool_size;
 citus.max_shared_pool_size
---------------------------------------------------------------------
 5
(1 row)

-- by default max_shared_pool_size equals to max_connections;
ALTER SYSTEM RESET citus.max_shared_pool_size;
SELECT pg_reload_conf();
 pg_reload_conf
---------------------------------------------------------------------
 t
(1 row)

SELECT pg_sleep(0.1);
 pg_sleep
---------------------------------------------------------------------

(1 row)

SHOW citus.max_shared_pool_size;
 citus.max_shared_pool_size
---------------------------------------------------------------------
 100
(1 row)

SHOW max_connections;
 max_connections
---------------------------------------------------------------------
 100
(1 row)

-- now, each node gets 16 connections as we force 1 connection per placement
BEGIN;
	SET LOCAL citus.force_max_query_parallelization TO ON;
	SELECT count(*) FROM test;
 count
---------------------------------------------------------------------
   101
(1 row)

	SELECT
		connection_count_to_node
	FROM
		citus_remote_connection_stats()
	WHERE
		port IN (SELECT node_port FROM master_get_active_worker_nodes()) AND
		database_name = 'regression'
	ORDER BY
		hostname, port;
 connection_count_to_node
---------------------------------------------------------------------
                       16
                       16
(2 rows)

COMMIT;
-- connection_retry_timeout cannot be smaller than node_connection_timeout
SET citus.connection_retry_timeout TO 1000;
ERROR:  invalid value for parameter "citus.connection_retry_timeout": 1000
DETAIL:  citus.connection_retry_timeout cannot be smaller than citus.node_connection_timeout.
-- in case other tests relies on these setting, reset them
ALTER SYSTEM RESET citus.distributed_deadlock_detection_factor;
ALTER SYSTEM RESET citus.recover_2pc_interval;
ALTER SYSTEM RESET citus.max_cached_conns_per_worker;
SELECT pg_reload_conf();
 pg_reload_conf
---------------------------------------------------------------------
 t
(1 row)

DROP SCHEMA shared_connection_stats CASCADE;
NOTICE:  drop cascades to table test