set enable_seqscan=off;
CREATE TABLE test_float8 (
	i float8
);
INSERT INTO test_float8 VALUES (-2),(-1),(0),(1),(2),(3);
CREATE INDEX idx_float8 ON test_float8 USING gin (i);
SELECT * FROM test_float8 WHERE i<1::float8 ORDER BY i;
 i  
----
 -2
 -1
  0
(3 rows)

SELECT * FROM test_float8 WHERE i<=1::float8 ORDER BY i;
 i  
----
 -2
 -1
  0
  1
(4 rows)

SELECT * FROM test_float8 WHERE i=1::float8 ORDER BY i;
 i 
---
 1
(1 row)

SELECT * FROM test_float8 WHERE i>=1::float8 ORDER BY i;
 i 
---
 1
 2
 3
(3 rows)

SELECT * FROM test_float8 WHERE i>1::float8 ORDER BY i;
 i 
---
 2
 3
(2 rows)

explain (costs off)
SELECT * FROM test_float8 WHERE i<1::float4 ORDER BY i;
                 QUERY PLAN                  
---------------------------------------------
 Sort
   Sort Key: i
   ->  Bitmap Heap Scan on test_float8
         Recheck Cond: (i < '1'::real)
         ->  Bitmap Index Scan on idx_float8
               Index Cond: (i < '1'::real)
(6 rows)

SELECT * FROM test_float8 WHERE i<1::float4 ORDER BY i;
 i  
----
 -2
 -1
  0
(3 rows)

SELECT * FROM test_float8 WHERE i<=1::float4 ORDER BY i;
 i  
----
 -2
 -1
  0
  1
(4 rows)

SELECT * FROM test_float8 WHERE i=1::float4 ORDER BY i;
 i 
---
 1
(1 row)

SELECT * FROM test_float8 WHERE i>=1::float4 ORDER BY i;
 i 
---
 1
 2
 3
(3 rows)

SELECT * FROM test_float8 WHERE i>1::float4 ORDER BY i;
 i 
---
 2
 3
(2 rows)