-- timestamp check
CREATE TABLE timestamptmp (a timestamp);
\copy timestamptmp from 'data/timestamp.data'
SET enable_seqscan=on;
SELECT count(*) FROM timestamptmp WHERE a <  '2004-10-26 08:55:08';
 count 
-------
   278
(1 row)

SELECT count(*) FROM timestamptmp WHERE a <= '2004-10-26 08:55:08';
 count 
-------
   279
(1 row)

SELECT count(*) FROM timestamptmp WHERE a  = '2004-10-26 08:55:08';
 count 
-------
     1
(1 row)

SELECT count(*) FROM timestamptmp WHERE a >= '2004-10-26 08:55:08';
 count 
-------
   290
(1 row)

SELECT count(*) FROM timestamptmp WHERE a >  '2004-10-26 08:55:08';
 count 
-------
   289
(1 row)

SELECT a, a <-> '2004-10-26 08:55:08' FROM timestamptmp ORDER BY a <-> '2004-10-26 08:55:08' LIMIT 3;
            a             |              ?column?              
--------------------------+------------------------------------
 Tue Oct 26 08:55:08 2004 | @ 0
 Sun Oct 31 06:35:03 2004 | @ 4 days 21 hours 39 mins 55 secs
 Mon Nov 29 20:12:43 2004 | @ 34 days 11 hours 17 mins 35 secs
(3 rows)

CREATE INDEX timestampidx ON timestamptmp USING gist ( a );
SET enable_seqscan=off;
SELECT count(*) FROM timestamptmp WHERE a <  '2004-10-26 08:55:08'::timestamp;
 count 
-------
   278
(1 row)

SELECT count(*) FROM timestamptmp WHERE a <= '2004-10-26 08:55:08'::timestamp;
 count 
-------
   279
(1 row)

SELECT count(*) FROM timestamptmp WHERE a  = '2004-10-26 08:55:08'::timestamp;
 count 
-------
     1
(1 row)

SELECT count(*) FROM timestamptmp WHERE a >= '2004-10-26 08:55:08'::timestamp;
 count 
-------
   290
(1 row)

SELECT count(*) FROM timestamptmp WHERE a >  '2004-10-26 08:55:08'::timestamp;
 count 
-------
   289
(1 row)

EXPLAIN (COSTS OFF)
SELECT a, a <-> '2004-10-26 08:55:08' FROM timestamptmp ORDER BY a <-> '2004-10-26 08:55:08' LIMIT 3;
                                    QUERY PLAN                                     
-----------------------------------------------------------------------------------
 Limit
   ->  Index Only Scan using timestampidx on timestamptmp
         Order By: (a <-> 'Tue Oct 26 08:55:08 2004'::timestamp without time zone)
(3 rows)

SELECT a, a <-> '2004-10-26 08:55:08' FROM timestamptmp ORDER BY a <-> '2004-10-26 08:55:08' LIMIT 3;
            a             |              ?column?              
--------------------------+------------------------------------
 Tue Oct 26 08:55:08 2004 | @ 0
 Sun Oct 31 06:35:03 2004 | @ 4 days 21 hours 39 mins 55 secs
 Mon Nov 29 20:12:43 2004 | @ 34 days 11 hours 17 mins 35 secs
(3 rows)