mysql> CREATE TABLE data_time (id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, data VARCHAR(64), ts TIMESTAMP);

mysql> CREATE TABLE data_random (id CHAR(32) NOT NULL PRIMARY KEY, data VARCHAR(64), ts TIMESTAMP);

mysql> INSERT INTO data_time VALUES ( NULL, 'Row 1', NULL); SELECT SLEEP(1);
mysql> INSERT INTO data_time VALUES ( NULL, 'Row 2', NULL); SELECT SLEEP(1);
mysql> INSERT INTO data_time VALUES ( NULL, 'Row 3', NULL); SELECT SLEEP(1);

mysql> INSERT INTO data_random VALUES ( MD5(CURRENT_TIMESTAMP()), 'Row 1', NULL); SELECT SLEEP(1);
mysql> INSERT INTO data_random VALUES ( MD5(CURRENT_TIMESTAMP()), 'Row 2', NULL); SELECT SLEEP(1);
mysql> INSERT INTO data_random VALUES ( MD5(CURRENT_TIMESTAMP()), 'Row 3', NULL); SELECT SLEEP(1);

mysql> CREATE TABLE `data_time` (
  `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `data` VARCHAR(64) DEFAULT NULL,
  `ts` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4

mysql> CREATE TABLE `data_random` (
  `id` CHAR(32) NOT NULL,
  `data` VARCHAR(64) DEFAULT NULL,
  `ts` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT

mysql> SELECT * FROM data_time;

[...]

mysql> SELECT * FROM data_random;

[...]