# # 2010-01-20 - OBN - Added check for variable value sameas I_S table # after variable value change # SET @start_global_value = @@global.max_join_size; SELECT @start_global_value; # # exists as global and session # select @@global.max_join_size; select @@session.max_join_size; show global variables like 'max_join_size'; show session variables like 'max_join_size'; select * from information_schema.global_variables where variable_name='max_join_size'; select * from information_schema.session_variables where variable_name='max_join_size'; # # show that it's writable # set global max_join_size=10; set session max_join_size=20; select @@global.max_join_size; select @@session.max_join_size; show global variables like 'max_join_size'; show session variables like 'max_join_size'; select * from information_schema.global_variables where variable_name='max_join_size'; select * from information_schema.session_variables where variable_name='max_join_size'; # # incorrect types # --error ER_WRONG_TYPE_FOR_VAR set global max_join_size=1.1; --error ER_WRONG_TYPE_FOR_VAR set global max_join_size=1e1; --error ER_WRONG_TYPE_FOR_VAR set global max_join_size="foo"; # # affects OPTION_BIG_SELECTS # select @@sql_big_selects; set max_join_size=cast(-1 as unsigned int); select @@sql_big_selects; set max_join_size=100; select @@sql_big_selects; SET @@global.max_join_size = @start_global_value; SELECT @@global.max_join_size;