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

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

SELECT * FROM test_text WHERE i='abc' ORDER BY i;
  i  
-----
 abc
(1 row)

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

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