SQL：

        SELECT
            COUNT(usr.id) as `total_results`
        FROM
            users as usr
            LEFT JOIN profile as prof
                ON prof.uid = usr.uid
        WHERE
            usr.username LIKE '%a%'
            OR
            prof.name LIKE '%a%'

用户索引：

uid - uid
username - username

个人资料索引

index1 - uid
index2 - uid,name
index3 - name

解释 ：

id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra
1   PRIMARY     usr     ALL     NULL    NULL    NULL    NULL    18387   
1   PRIMARY     prof    ref     index2,index1   index2  8   site.usr.uid    1   Using where
2   DEPENDENT SUBQUERY  sub     ref     i3,index1,index2    i3  16  site.usr.uid,const  1   Using index

上面的查询大约需要0.1221

我怎样才能使其运行更快？