select 
1p < 2p, 1p <= 2p, cast(null as pgint4) < 1p, cast(null as pgint4) <= 1p,
1p = 2p, 1p != 2p, cast(null as pgint4) = 1p, cast(null as pgint4) != 1p,
1p > 2p, 1p >= 2p, cast(null as pgint4) > 1p, cast(null as pgint4) >= 1p,
1p is distinct from 2p, 
1p is not distinct from 2p, 
cast(null as pgint4) is distinct from cast(null as pgint4),
cast(null as pgint4) is not distinct from cast(null as pgint4),
1p is distinct from cast(null as pgint4),
1p is not distinct from cast(null as pgint4),
cast(null as pgint4) is distinct from 1p,
cast(null as pgint4) is not distinct from 1p;
