mysql 5.6 rails active_record migration text max lengths for a database created with utf8

mysql_max_text_limits_active_record.rb

# just an active_record migration example for reference
# source of this logic: https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

class CreateMetaTexts < ActiveRecord::Migration
  def up
    create_table :meta_texts do |t|

      t.text :default_text_63KB, limit: 63.kilobytes # 64512 < 65535 limit for when text datatype changes to mediumtext datatype 
      t.text :medium_text_64KB, limit: 64.kilobytes # 65536 > 65535 limit and triggers text datatype to mediumtext datatype
      t.text :medium_text_15MB, limit: 15.megabytes # 15728640 < 16777215 limit for when mediumtext changes to longtext datatype
      t.text :long_text_16MB, limit: 16.megabytes # 16777216 > 16777215 limit and triggers mediumtext datatype to longtext datatype

    end
  end
  
  def down
    drop_table :meta_texts
  end  
end

=begin

CREATE TABLE `meta_texts` (`id` int(11) DEFAULT NULL auto_increment PRIMARY KEY,
`default_text_63KB` text, 
`medium_text_64KB` mediumtext, 
`medium_text_15MB` mediumtext, 
`long_text_16MB` longtext) ENGINE=InnoDB
=end