TEXT列的MySQL默认值行为异常，为什么？

我试图做的是避免在INSERT中列出我的TEXT列，它们将具有默认的''（空字符串）。

我设法为TEXT列设置了一个默认的''值，但是它生成了警告，并且我看不到表结构上发生了什么变化。

请检查下面的代码以重现该问题。

DROP TABLE IF EXISTS `text_test`;

CREATE TABLE `text_test` (
    `id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
    `text` TEXT NOT NULL,
    PRIMARY KEY (`id`)
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
;
-- created OK

SHOW CREATE TABLE `text_test`;
-- CREATE TABLE `text_test` (
--   `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
--   `text` text COLLATE utf8_unicode_ci NOT NULL,
--   PRIMARY KEY (`id`)
-- ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
-- no surprises here...

INSERT INTO `text_test` () VALUES ();
-- warning: text has no default value

SELECT * FROM `text_test`;
-- id=1, text=''

ALTER TABLE `text_test` 
    CHANGE COLUMN `text` `text` TEXT NOT NULL DEFAULT '' COLLATE 'utf8_unicode_ci' AFTER `id`;
-- warning: blob/text cannot have default...

SHOW CREATE TABLE `text_test`;
-- CREATE TABLE `text_test` (
--   `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
--   `text` text COLLATE utf8_unicode_ci NOT NULL,
--   PRIMARY KEY (`id`)
-- ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
-- no surprises, seems like the table did not change at all...

INSERT INTO `text_test` () VALUES ();
-- no warning generated, but why if the table structure is still the same??

SELECT * FROM `text_test`;
-- id=1, text=''
-- id=2, text=''

我的服务器信息：

SHOW VARIABLES LIKE "%version%";
-- "Variable_name"           "Value"
-- "innodb_version"          "5.1.73-14.6"
-- "protocol_version"        "10"
-- "version"                 "5.1.73-rel14.11-log"
-- "version_comment"         "(Percona Server (GPL), 14.11)"
-- "version_compile_machine" "x86_64"
-- "version_compile_os"      "debian-linux-gnu"