select pg_sleep(2);
 pg_sleep 
----------
 
(1 row)

insert into cmpTS values(1,current_timestamp);
drop table tx;
insert into cmpTS values(2,current_timestamp);
select true 
from cmpTS a, cmpTS b 
where a.c1 = 1 and b.c1 = 2 and (b.ts-a.ts)>'00:00:02';
 bool 
------
 t
(1 row)

select a.ts as ts1,b.ts as ts2 
from cmpTS a, cmpTS b 
where a.c1 = 1 and b.c1 = 2 and (b.ts-a.ts)>'00:00:02';
--?.*
--?.*
--?.*
(1 row)