SELECT pgperf._get_server_version() >= 90;
 ?column? 
----------
 t
(1 row)

SELECT pgperf._get_server_version() <= 94;
 ?column? 
----------
 t
(1 row)

SELECT pgperf._get_server_version() < 90;
 ?column? 
----------
 f
(1 row)

SELECT pgperf._get_server_version() > 94;
 ?column? 
----------
 f
(1 row)