Trigger not working with longtext field - mysql

Question

I have 2 MySQL table name uploads and uploads_log.
uploads table has a field name json_values (datatype: longtext)
uploads_log table has 2 fields old_value, new_value (both datatype: longtext)
On After UPDATE of uploads table I have written a trigger which just put the whole content of uploads.json_values into uploads_log table's old_value, new_value.
trigger is
BEGIN
IF (NEW.json_values != OLD.json_values) THEN
INSERT INTO uploads_log (`file_id`, `user_id`, `field_name`, `old_value`, `new_value`, `ip`, `created_at`)
VALUES (OLD.`file_id`,
OLD.`user_id`,
'json_values',
OLD.json_values,
NEW.json_values,
NEW.user_ip,
NOW());
END IF;
END
My issue is: When I'm editing small string in uploads.json_values my trigger is working fine, but when Im editting some realy long string like 378369 characters long. I'm getting the following error.
SQLSTATE[42000]: Syntax error or access violation: 1118 Row size too large (> 8126). Changing some columns to TEXT or BLOB or using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED may help. In current row format, BLOB prefix of 768 bytes is stored inline.
I try to debug the issue I removed the trigger and EDITED uploads.json_values with long string it workes fine, and I manually INSERTED that long string into uploads_log.old_value then also it works fine, So the issue is with the trigger.
Is trigger has some limitataion of length?
Both the table uses Storage Engine: InnoDB and MySQL Version is 5.6.21.
uploads table Structure
CREATE TABLE `uploads` (
`file_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`user_id` int(11) unsigned NOT NULL,
`json_values` longtext COLLATE utf8_unicode_ci NOT NULL,
`read_values` longtext COLLATE utf8_unicode_ci,
`user_ip` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,
PRIMARY KEY (`file_id`),
KEY `user_id` (`user_id`)
) ENGINE=InnoDB AUTO_INCREMENT=34444 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
uploads_log table Structure
CREATE TABLE `uploads_log` (
`action_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`file_id` int(11) unsigned DEFAULT NULL,
`user_id` int(11) unsigned DEFAULT NULL,
`field_name` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`old_value` longtext COLLATE utf8_unicode_ci,
`new_value` longtext COLLATE utf8_unicode_ci,
`ip` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
`created_at` datetime DEFAULT NULL,
PRIMARY KEY (`action_id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
I found this question and this one, but it is not related to UPDATE trigger.
Any help/suggestion will be very much appreciated.
Thanks.

Answer 1

I also had some similar issue but not with trigger this question helped me out.
Change innodb_log_file_size value located in C:\xampp\mysql\bin\my.ini (if you are using XAMPP) to something higher than 5M.
or as pointed out by #Vatev you can set innodb_log_file_size = 128M
You can use this MySQL command to get the innodb_log_file_size value, it will give you the result in Byte.