-Note the "binary" migration will not work for the LONGBLOB type in MySQL for the file contents column. You may need to craft a SQL statement for your migration, depending on which database server you are using. Here's an example migration for MySQL:
+Note the "limit" option (when used for MySQL) will create a BLOB of the appropriate size (up to 4.gigabytes will create a LONGBLOB).
To avoid performance problems loading all of the BLOB columns every time you access your ActiveRecord object, a class method is provided on your model called `select_without_file_columns_for`. This is set to a `:select` scope hash that will instruct `ActiveRecord::Base.find` to load all of the columns except the BLOB/file data columns.