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

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

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

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

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

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

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

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

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

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

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

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