SET @start_global_value = @@global.XENGINE_ENABLE_2PC;
SELECT @start_global_value;
@start_global_value
1
"Trying to set variable @@global.XENGINE_ENABLE_2PC to 444. It should fail because it is readonly."
SET @@global.XENGINE_ENABLE_2PC   = 444;
ERROR HY000: Variable 'xengine_enable_2pc' is a read only variable