SELECT name, type, size IS DISTINCT FROM 0 AS size
FROM pg_dsm_registry_allocations
WHERE name like 'test_dsm_registry%' ORDER BY name;
 name | type | size 
------+------+------
(0 rows)

CREATE EXTENSION test_dsm_registry;
SELECT set_val_in_shmem(1236);
 set_val_in_shmem 
------------------
 
(1 row)

SELECT set_val_in_hash('test', '1414');
 set_val_in_hash 
-----------------
 
(1 row)

\c
SELECT get_val_in_shmem();
 get_val_in_shmem 
------------------
             1236
(1 row)

SELECT get_val_in_hash('test');
 get_val_in_hash 
-----------------
 1414
(1 row)

\c
SELECT name, type, size IS DISTINCT FROM 0 AS size
FROM pg_dsm_registry_allocations
WHERE name like 'test_dsm_registry%' ORDER BY name;
          name          |  type   | size 
------------------------+---------+------
 test_dsm_registry_dsa  | area    | t
 test_dsm_registry_dsm  | segment | t
 test_dsm_registry_hash | hash    | t
(3 rows)