我在 MySQL 中有下表：
CREATE TABLE tweetdb(
tweetid BIGINT(18) UNSIGNED NOT NULL,
userid INT(10) UNSIGNED NOT NULL,
timestamp CHAR(14),
tweet TEXT,
score TINYINT,
PRIMARY KEY(tweetid, userid)
) ENGINE=MYISAM PARTITION BY KEY(userid) PARTITIONS 101;
+-----------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+---------------------+------+-----+---------+-------+
| tweetid | bigint(18) unsigned | NO | PRI | NULL | |
| userid | int(10) unsigned | NO | PRI | NULL | |
| timestamp | char(14) | YES | | NULL | |
| tweet | text | YES | | NULL | |
| score | tinyint(4) | YES | | NULL | |
+-----------+---------------------+------+-----+---------+-------+
5 rows in set (0.29 sec)
我在这个表中有 2.1 亿行。我的 Undertow 服务器（Java 应用程序）发送带有以下选择查询的 GET：
"SELECT test.tweetdb.tweetid, test.tweetdb.tweet, test.tweetdb.score FROM test.tweetdb WHERE test.tweetdb.userid = 287543000 AND test.tweetdb.timestamp = 20140420000829;"
我使用用户 ID 和时间戳来获取结果，因为它是我唯一可用于测试数据库的数据。该数据库用于只读目的，没有写入/更新。
我还在桌子上使用了索引。
mysql> SHOW INDEX FROM tweetdb;
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| tweetdb | 1 | id_index | 1 | userid | A | 1 | NULL | NULL | YES | BTREE | | |
| tweetdb | 1 | id_index | 2 | timestamp | A | 1 | NULL | NULL | YES | BTREE | | |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)
现在，即使在使用分区和应用主键之后，也需要将近 1 秒才能得到正确的响应，这非常长。我的应用程序的吞吐量必须至少为每秒 6000 个请求。
硬件配置：
我正在运行 Undertow 服务器（前端）来查询 Amazon M1.large 实例上的 Mysql 服务器（后端）。为了避免延迟，我在同一个实例上运行两台服务器。
谁能帮我吗？我的想法不多了。谢谢！
更新
mysql> EXPLAIN SELECT * FROM test.tweetdb LIMIT 1;
+----+-------------+---------+------+---------------+------+---------+------+-----------+-------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------+------+---------------+------+---------+------+-----------+-------+
| 1 | SIMPLE | tweetdb | ALL | NULL | NULL | NULL | NULL | 270119913 | |
+----+-------------+---------+------+---------------+------+---------+------+-----------+-------+
1 row in set (3.67 sec)
mysql> EXPLAIN SELECT * FROM test.tweetdb WHERE test.tweetdb.userid=287543000 AND test.tweetdb.timestamp=20140420000829;
+----+-------------+---------+------+---------------+------+---------+------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------+------+---------------+------+---------+------+---------+-------------+
| 1 | SIMPLE | tweetdb | ALL | NULL | NULL | NULL | NULL | 2657601 | Using where |
+----+-------------+---------+------+---------------+------+---------+------+---------+-------------+
1 row in set (0.00 sec)
Undertow 前端服务器的时间
