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; [...]