CREATE TABLE t1 (
d datetime default NULL
) ENGINE=MyISAM;
INSERT INTO t1 VALUES ('2002-10-24 14:50:32'),('2002-10-24 14:50:33'),('2002-10-24 14:50:34'),('2002-10-24 14:50:34'),('2002-10-24 14:50:34'),('2002-10-24 14:50:35'),('2002-10-24 14:50:35'),('2002-10-24 14:50:35'),('2002-10-24 14:50:35'),('2002-10-24 14:50:36'),('2002-10-24 14:50:36'),('2002-10-24 14:50:36'),('2002-10-24 14:50:36'),('2002-10-24 14:50:37'),('2002-10-24 14:50:37'),('2002-10-24 14:50:37'),('2002-10-24 14:50:37'),('2002-10-24 14:50:38'),('2002-10-24 14:50:38'),('2002-10-24 14:50:38'),('2002-10-24 14:50:39'),('2002-10-24 14:50:39'),('2002-10-24 14:50:39'),('2002-10-24 14:50:39'),('2002-10-24 14:50:40'),('2002-10-24 14:50:40'),('2002-10-24 14:50:40');
flush status;
select * from t1 group by d;
d
2002-10-24 14:50:32
2002-10-24 14:50:33
2002-10-24 14:50:34
2002-10-24 14:50:35
2002-10-24 14:50:36
2002-10-24 14:50:37
2002-10-24 14:50:38
2002-10-24 14:50:39
2002-10-24 14:50:40
show status like "created_tmp%tables";
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_tables	1
drop table t1;
DROP TABLE IF EXISTS t1;
CREATE TEMPORARY TABLE t1(a INT) ENGINE=MyISAM;
INSERT INTO t1 VALUES (1), (2), (3);
OPTIMIZE TABLE t1;
Table	Op	Msg_type	Msg_text
test.t1	optimize	status	OK
INSERT INTO t1 VALUES (1), (2), (3);
REPAIR TABLE t1;
Table	Op	Msg_type	Msg_text
test.t1	repair	status	OK
DROP TABLES t1;