# 2010-01-27 - Added # --source include/have_innodb.inc SET @start_global_value = @@global.innodb_read_ahead_threshold; SELECT @start_global_value; # # exists as global only # --echo Valid values are between 0 and 64 select @@global.innodb_read_ahead_threshold between 0 and 64; select @@global.innodb_read_ahead_threshold; --error ER_INCORRECT_GLOBAL_LOCAL_VAR select @@session.innodb_read_ahead_threshold; show global variables like 'innodb_read_ahead_threshold'; show session variables like 'innodb_read_ahead_threshold'; select * from information_schema.global_variables where variable_name='innodb_read_ahead_threshold'; select * from information_schema.session_variables where variable_name='innodb_read_ahead_threshold'; # # show that it's writable # set global innodb_read_ahead_threshold=10; select @@global.innodb_read_ahead_threshold; select * from information_schema.global_variables where variable_name='innodb_read_ahead_threshold'; select * from information_schema.session_variables where variable_name='innodb_read_ahead_threshold'; --error ER_GLOBAL_VARIABLE set session innodb_read_ahead_threshold=1; # # incorrect types # --error ER_WRONG_TYPE_FOR_VAR set global innodb_read_ahead_threshold=1.1; --error ER_WRONG_TYPE_FOR_VAR set global innodb_read_ahead_threshold=1e1; --error ER_WRONG_TYPE_FOR_VAR set global innodb_read_ahead_threshold="foo"; set global innodb_read_ahead_threshold=-7; select @@global.innodb_read_ahead_threshold; select * from information_schema.global_variables where variable_name='innodb_read_ahead_threshold'; set global innodb_read_ahead_threshold=96; select @@global.innodb_read_ahead_threshold; select * from information_schema.global_variables where variable_name='innodb_read_ahead_threshold'; # # min/max values # set global innodb_read_ahead_threshold=0; select @@global.innodb_read_ahead_threshold; set global innodb_read_ahead_threshold=64; select @@global.innodb_read_ahead_threshold; SET @@global.innodb_read_ahead_threshold = @start_global_value; SELECT @@global.innodb_read_ahead_threshold;