In my production enviornment, some feedback entries in feedback module were trimmed since the 'value' field in 'mdl_feedback_value' table is set to varchar(255).

After investigation, it is found that the data type of this field is ''TEXT' in the original installation scripts (both mysql.sql and install.xml). However, in migrate2utf8.xml, following line is found.

<FIELD name="value" method="PHP_FUNCTION" type="varchar" length="255">

I'm not sure if this is the cause of the problem but I have ever run the migration script in production. In my local, i didn't run the migration and the data type of this field is still 'TEXT'.

In fact, not only this table was affected, but also the mdl_log, mdl_log_display and some other tables.