1SET @start_global_value = @@global.optimizer_trace_features; 2SELECT @start_global_value; 3@start_global_value 4greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 5select @@global.optimizer_trace_features; 6@@global.optimizer_trace_features 7greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 8select @@session.optimizer_trace_features; 9@@session.optimizer_trace_features 10greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 11show global variables like 'optimizer_trace_features'; 12Variable_name Value 13optimizer_trace_features greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 14show session variables like 'optimizer_trace_features'; 15Variable_name Value 16optimizer_trace_features greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 17select * from information_schema.global_variables where variable_name='optimizer_trace_features'; 18VARIABLE_NAME VARIABLE_VALUE 19OPTIMIZER_TRACE_FEATURES greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 20select * from information_schema.session_variables where variable_name='optimizer_trace_features'; 21VARIABLE_NAME VARIABLE_VALUE 22OPTIMIZER_TRACE_FEATURES greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 23set global optimizer_trace_features=2; 24select @@global.optimizer_trace_features; 25@@global.optimizer_trace_features 26greedy_search=off,range_optimizer=on,dynamic_range=off,repeated_subselect=off 27set session optimizer_trace_features=2; 28select @@session.optimizer_trace_features; 29@@session.optimizer_trace_features 30greedy_search=off,range_optimizer=on,dynamic_range=off,repeated_subselect=off 31set global optimizer_trace_features=0; 32select @@global.optimizer_trace_features; 33@@global.optimizer_trace_features 34greedy_search=off,range_optimizer=off,dynamic_range=off,repeated_subselect=off 35set session optimizer_trace_features=0; 36select @@session.optimizer_trace_features; 37@@session.optimizer_trace_features 38greedy_search=off,range_optimizer=off,dynamic_range=off,repeated_subselect=off 39set session optimizer_trace_features=default; 40select @@session.optimizer_trace_features; 41@@session.optimizer_trace_features 42greedy_search=off,range_optimizer=off,dynamic_range=off,repeated_subselect=off 43set global optimizer_trace_features=1.1; 44ERROR 42000: Incorrect argument type to variable 'optimizer_trace_features' 45set global optimizer_trace_features=1e1; 46ERROR 42000: Incorrect argument type to variable 'optimizer_trace_features' 47set session optimizer_trace_features="foobar"; 48ERROR 42000: Variable 'optimizer_trace_features' can't be set to the value of 'foobar' 49SET @@global.optimizer_trace_features = @start_global_value; 50SELECT @@global.optimizer_trace_features; 51@@global.optimizer_trace_features 52greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on 53