mysql 设置optimizer_switch属性值报错

mysql> set optimizer_switch='mrr=on,mrr_cost_based=on,batched_key_access=on';
1231 - Variable 'optimizer_switch' can't be set to the value of 'mrr=on,mrr_cost_based=on,batched_key_access=on'
mysql>

参考：http://blog.csdn.net/aeolus_pu/article/details/9120771

还是报错，我用的mysql6.0版本的：
set global optimizer_switch='mrr=on,mrr_cost_based=on,batched_key_access=on';
1231 - Variable 'optimizer_switch' can't be set to the value of 'mrr=on,mrr_cost_based=on,batched_key_access=on'