set enable_seqscan=off;
CREATE TABLE test_bpchar (
	i char(10)
);
INSERT INTO test_bpchar VALUES ('a'),('ab'),('abc'),('abc   '),('abb'),('axy'),('xyz'),('xyz  ');
CREATE INDEX idx_bpchar ON test_bpchar USING gin (i);
SELECT * FROM test_bpchar WHERE i<'abc' ORDER BY i;
     i      
------------
 a         
 ab        
 abb       
(3 rows)

SELECT * FROM test_bpchar WHERE i<='abc' ORDER BY i;
     i      
------------
 a         
 ab        
 abb       
 abc       
 abc       
(5 rows)

SELECT * FROM test_bpchar WHERE i='abc' ORDER BY i;
     i      
------------
 abc       
 abc       
(2 rows)

SELECT * FROM test_bpchar WHERE i='abc  ' ORDER BY i;
     i      
------------
 abc       
 abc       
(2 rows)

SELECT * FROM test_bpchar WHERE i>='abc' ORDER BY i;
     i      
------------
 abc       
 abc       
 axy       
 xyz       
 xyz       
(5 rows)

SELECT * FROM test_bpchar WHERE i>'abc' ORDER BY i;
     i      
------------
 axy       
 xyz       
 xyz       
(3 rows)

EXPLAIN (COSTS OFF) SELECT * FROM test_bpchar WHERE i<'abc' ORDER BY i;
                  QUERY PLAN                   
-----------------------------------------------
 Sort
   Sort Key: i
   ->  Bitmap Heap Scan on test_bpchar
         Recheck Cond: (i < 'abc'::bpchar)
         ->  Bitmap Index Scan on idx_bpchar
               Index Cond: (i < 'abc'::bpchar)
(6 rows)

EXPLAIN (COSTS OFF) SELECT * FROM test_bpchar WHERE i<='abc' ORDER BY i;
                   QUERY PLAN                   
------------------------------------------------
 Sort
   Sort Key: i
   ->  Bitmap Heap Scan on test_bpchar
         Recheck Cond: (i <= 'abc'::bpchar)
         ->  Bitmap Index Scan on idx_bpchar
               Index Cond: (i <= 'abc'::bpchar)
(6 rows)

EXPLAIN (COSTS OFF) SELECT * FROM test_bpchar WHERE i='abc' ORDER BY i;
               QUERY PLAN                
-----------------------------------------
 Bitmap Heap Scan on test_bpchar
   Recheck Cond: (i = 'abc'::bpchar)
   ->  Bitmap Index Scan on idx_bpchar
         Index Cond: (i = 'abc'::bpchar)
(4 rows)

EXPLAIN (COSTS OFF) SELECT * FROM test_bpchar WHERE i>='abc' ORDER BY i;
                   QUERY PLAN                   
------------------------------------------------
 Sort
   Sort Key: i
   ->  Bitmap Heap Scan on test_bpchar
         Recheck Cond: (i >= 'abc'::bpchar)
         ->  Bitmap Index Scan on idx_bpchar
               Index Cond: (i >= 'abc'::bpchar)
(6 rows)

EXPLAIN (COSTS OFF) SELECT * FROM test_bpchar WHERE i>'abc' ORDER BY i;
                  QUERY PLAN                   
-----------------------------------------------
 Sort
   Sort Key: i
   ->  Bitmap Heap Scan on test_bpchar
         Recheck Cond: (i > 'abc'::bpchar)
         ->  Bitmap Index Scan on idx_bpchar
               Index Cond: (i > 'abc'::bpchar)
(6 rows)