如何使用超过100k的记录优化查询

Question

我的查询运行超过25秒，我无法理解为什么

SELECT transactions . * , m.member_id, m.group_id, m.username,    preffered_currency, transactions.payment_method
FROM `transactions`
JOIN `members` `m` ON `m`.`member_id` = `transactions`.`member_id`
ORDER BY `paid_microtime`
LIMIT 25 

这是来自事务（~100k记录）表

的索引

transactions    0   PRIMARY     1   transaction_id  A   92304   NULL    NULL        BTREE       
transactions    1   member_id   1   member_id   A   44  NULL    NULL        BTREE       
transactions    1   payment_method  1   payment_method  A   70  NULL    NULL        BTREE       
transactions    1   child_method    1   child_method    A   234     NULL    NULL        BTREE       
transactions    1   check_ballance  1   check_ballance  A   2   NULL    NULL        BTREE       
transactions    1   transaction_status  1   transaction_status  A   18  NULL    NULL        BTREE       
transactions    1   dt  1   dt  A   92304   NULL    NULL        BTREE       
transactions    1   transaction_type    1   transaction_type    A   2   NULL    NULL        BTREE   
transactions    1   paid_microtime  1   paid_microtime  A   92317   NULL    NULL        BTREE       

来自会员（30条记录）表

members     0   PRIMARY     1   member_id   A   28  NULL    NULL        BTREE       
members     1   username    1   username    A   28  NULL    NULL        BTREE       
members     1   ban     1   ban     A   4   NULL    NULL        BTREE       
members     1   active  1   active  A   4   NULL    NULL        BTREE   

你能看到我的查询有什么问题吗？这需要25秒吗？

编辑： 解释结果

id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra 
1   SIMPLE  m   ALL     PRIMARY     NULL    NULL    NULL    28  Using temporary; Using filesort
1   SIMPLE  transactions    ref     member_id   member_id   4   tadam.m.member_id   2097    Using index condition

Answer 1

这是缺乏RAM问题。