select @@global.pseudo_thread_id; ERROR HY000: Variable 'pseudo_thread_id' is a SESSION variable select @@session.pseudo_thread_id between 1 and 10000; @@session.pseudo_thread_id between 1 and 10000 1 should be empty show global variables like 'pseudo_thread_id'; Variable_name Value show session variables like 'pseudo_thread_id'; Variable_name Value pseudo_thread_id # should be empty select * from information_schema.global_variables where variable_name='pseudo_thread_id'; VARIABLE_NAME VARIABLE_VALUE select @@session.pseudo_thread_id = variable_value from information_schema.session_variables where variable_name='pseudo_thread_id'; @@session.pseudo_thread_id = variable_value 1 set session pseudo_thread_id=42; select @@session.pseudo_thread_id; @@session.pseudo_thread_id 42 select * from information_schema.global_variables where variable_name='pseudo_thread_id'; VARIABLE_NAME VARIABLE_VALUE select variable_value from information_schema.session_variables where variable_name='pseudo_thread_id'; variable_value 42 set global pseudo_thread_id=1; ERROR HY000: Variable 'pseudo_thread_id' is a SESSION variable and can't be used with SET GLOBAL set session pseudo_thread_id=1.1; ERROR 42000: Incorrect argument type to variable 'pseudo_thread_id' set session pseudo_thread_id=1e1; ERROR 42000: Incorrect argument type to variable 'pseudo_thread_id' set session pseudo_thread_id="foo"; ERROR 42000: Incorrect argument type to variable 'pseudo_thread_id'