text: #
  # only global
  #
  select @@global.ft_stopword_file;
  --error ER_INCORRECT_GLOBAL_LOCAL_VAR
  select @@session.ft_stopword_file;
  show global variables like 'ft_stopword_file';
  show session variables like 'ft_stopword_file';
  select * from information_schema.global_variables where variable_name='ft_stopword_file';
  select * from information_schema.session_variables where variable_name='ft_stopword_file';
  
  #
  # show that it's read-only
  #
  --error ER_INCORRECT_GLOBAL_LOCAL_VAR
  set global ft_stopword_file=1;
  --error ER_INCORRECT_GLOBAL_LOCAL_VAR
  set session ft_stopword_file=1;
  
  