--source include/not_embedded.inc let $var= slave_parallel_workers; eval set @save.$var= @@global.$var; # # exists as global only # --error ER_INCORRECT_GLOBAL_LOCAL_VAR eval select @@session.$var; select variable_name from information_schema.global_variables where variable_name='$var'; select variable_name from information_schema.session_variables where variable_name='$var'; # # show that it's writable # let $value= 0; eval set @@global.$var= $value; eval select @@global.$var; # # incorrect types # --error ER_WRONG_TYPE_FOR_VAR eval set @@global.$var= 1.1; --error ER_WRONG_TYPE_FOR_VAR eval set @@global.$var= "foo"; # # min/max values # eval set @@global.$var= 0; eval set @@global.$var= cast(-1 as unsigned int); eval select @@global.$var as "truncated to the maximum"; # cleanup eval set @@global.$var= @save.$var;