dex_condition_pushdown=on'
影响，如果我们设置optimizer_switch='index_condition_pushdown=off'再来看一下
set? optimizer_switch='index_condition_pushdown=off'
?mysql> explain select * from testicp where a=1 and b<10;
?+----+-------------+---------+-------+---------------+------+---------+------+------+-------------+
?| id | select_type | table? | type? | possible_keys | key? | key_len | ref? | rows | Extra? ? ? |
?+----+-------------+---------+-------+---------------+------+---------+------+------+-------------+
?|? 1 | SIMPLE? ? ? | testicp | range | A? ? ? ? ? ? | A? ? | 10? ? ? | NULL |? ? 1 | Using where |
?+----+-------------+---------+-------+---------------+------+---------+------+------+-------------+
?1 row in set (0.01 sec)
可以看到这里变成了Using where，这代表没有使用icp。