Understanding default values of general configuration parameters related to resource queue

sachi=# show max_resource_portals_per_transaction;

max_resource_portals_per_transaction 

--------------------------------------

 64

(1 row)

max_resource_portals_per_transaction Sets the maximum number of simultaneously open cursors allowed per transaction. Note that an open cursor will hold an active query slot in a resource queue.

sachi=# show max_resource_queues;

 max_resource_queues 

---------------------

 9

(1 row)

max_resource_queues parameter Sets the maximum number of resource queues.

sachi=# show resource_select_only;

 resource_select_only 

----------------------

 off

(1 row)

a) If resource_select_only parameter is set to on means only SELECT, SELECT INTO, CREATE TABLE AS SELECT, and DECLARE CURSOR commands are evaluated.

b) If resource_select_only parameter is set off means INSERT, UPDATE, and DELETE commands will be evaluated as well.

sachi=# show resource_cleanup_gangs_on_wait;

 resource_cleanup_gangs_on_wait 

--------------------------------

 on

(1 row)

If resource_cleanup_gangs_on_wait is set to on means it cleans up idle segment worker processes before taking a slot in the resource queue.

sachi=# show stats_queue_level;

 stats_queue_level 

-------------------

 off

(1 row)

If set to on, stats_queue_level enables statistics collection on resource queue usage, which can then be viewed by querying the pg_stat_resqueues system view.

sachi=#