SELECT pgperf.create_snapshot_pg_locks(0);
 create_snapshot_pg_locks 
--------------------------
 t
(1 row)

SELECT count(*) FROM pgperf.snapshot_pg_locks;
 count 
-------
     4
(1 row)

SELECT pgperf.create_snapshot_pg_locks(1);
 create_snapshot_pg_locks 
--------------------------
 t
(1 row)

SELECT count(*) FROM pgperf.snapshot_pg_locks;
 count 
-------
     8
(1 row)

SELECT pgperf.create_snapshot_pg_locks(2);
 create_snapshot_pg_locks 
--------------------------
 t
(1 row)

SELECT count(*) FROM pgperf.snapshot_pg_locks;
 count 
-------
    12
(1 row)

SELECT pgperf.delete_snapshot_pg_locks(1);
 delete_snapshot_pg_locks 
--------------------------
 t
(1 row)

SELECT count(*) FROM pgperf.snapshot_pg_locks;
 count 
-------
     8
(1 row)

SELECT pgperf.delete_snapshot_pg_locks(2);
 delete_snapshot_pg_locks 
--------------------------
 t
(1 row)

SELECT count(*) FROM pgperf.snapshot_pg_locks;
 count 
-------
     4
(1 row)

SELECT pgperf.delete_snapshot_pg_locks(0);
 delete_snapshot_pg_locks 
--------------------------
 t
(1 row)

SELECT count(*) FROM pgperf.snapshot_pg_locks;
 count 
-------
     0
(1 row)