#
# only global
#
select @@global.thread_concurrency;
--error ER_INCORRECT_GLOBAL_LOCAL_VAR
select @@session.thread_concurrency;
show global variables like 'thread_concurrency';
show session variables like 'thread_concurrency';
select * from information_schema.global_variables where variable_name='thread_concurrency';
select * from information_schema.session_variables where variable_name='thread_concurrency';

#
# show that it's read-only
#
--error ER_INCORRECT_GLOBAL_LOCAL_VAR
set global thread_concurrency=1;
--error ER_INCORRECT_GLOBAL_LOCAL_VAR
set session thread_concurrency=1;
