^^&&^^

Edit File: optimizer_trace_features_basic.test

--source include/have_optimizer_trace.inc

SET @start_global_value = @@global.optimizer_trace_features;
SELECT @start_global_value;

#
# exists as global and session
#
select @@global.optimizer_trace_features;
select @@session.optimizer_trace_features;
show global variables like 'optimizer_trace_features';
show session variables like 'optimizer_trace_features';
select * from information_schema.global_variables where variable_name='optimizer_trace_features';
select * from information_schema.session_variables where variable_name='optimizer_trace_features';

#
# show that it's writable
#
set global optimizer_trace_features=2;
select @@global.optimizer_trace_features;
set session optimizer_trace_features=2;
select @@session.optimizer_trace_features;
set global optimizer_trace_features=0;
select @@global.optimizer_trace_features;
set session optimizer_trace_features=0;
select @@session.optimizer_trace_features;
set session optimizer_trace_features=default;
select @@session.optimizer_trace_features;

#
# incorrect assignments
#
--error ER_WRONG_TYPE_FOR_VAR
set global optimizer_trace_features=1.1;
--error ER_WRONG_TYPE_FOR_VAR
set global optimizer_trace_features=1e1;
--error ER_WRONG_VALUE_FOR_VAR
set session optimizer_trace_features="foobar";

SET @@global.optimizer_trace_features = @start_global_value;
SELECT @@global.optimizer_trace_features;