--source include/not_embedded.inc SET @start_global_value = @@global.slave_checkpoint_group; SELECT @start_global_value; # # exists as global only # select @@global.slave_checkpoint_group; --error ER_INCORRECT_GLOBAL_LOCAL_VAR select @@session.slave_checkpoint_group; show global variables like 'slave_checkpoint_group'; show session variables like 'slave_checkpoint_group'; select * from information_schema.global_variables where variable_name='slave_checkpoint_group'; select * from information_schema.session_variables where variable_name='slave_checkpoint_group'; # # show that it's writable # set global slave_checkpoint_group=1024; select @@global.slave_checkpoint_group; --error ER_GLOBAL_VARIABLE set session slave_checkpoint_group=1024; # # incorrect types # --error ER_WRONG_TYPE_FOR_VAR set global slave_checkpoint_group=1.1; --error ER_WRONG_TYPE_FOR_VAR set global slave_checkpoint_group=1e1; --error ER_WRONG_TYPE_FOR_VAR set global slave_checkpoint_group="foo"; # # min/max values # set global slave_checkpoint_group=0; set global slave_checkpoint_group=cast(-1 as unsigned int); select @@global.slave_checkpoint_group as "truncated to the maximum" ; SET @@global.slave_checkpoint_group = @start_global_value; SELECT @@global.slave_checkpoint_group;