原文:http://blog.chinaunix.net/u/29134/showart_493359.html
二、具体测试
1、我们来看一下查询性能比较：
1)、单表查询
mysql> select count(*) from category where parent_id in (22,20);
+----------+
| count(*) |
+----------+
| 17002 |
+----------+
1 row in set (0.03 sec)
mysql> select count(*) from category_part where parent_id in (22,20);
+----------+
| count(*) |
+----------+
| 17002 |
+----------+
1 row in set (0.02 sec)
分区表普通的做了索引的速度上快了一点，不过差别不是很大。
mysql> explain select count(*) from category where parent_id in (22,20);
+----+-------------+----------+-------+---------------+-------------+---------+------+-------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+----------+-------+---------------+-------------+---------+------+-------+--------------------------+
| 1 | SIMPLE | category | range | f_parent_id | f_parent_id | 4 | NULL | 14335 | Using where; Using index |
+----+-------------+----------+-------+---------------+-------------+---------+------+-------+--------------------------+
1 row in set (0.00 sec)
mysql> explain partitions select count(*) from category_part where parent_id in (22,20);
+----+-------------+---------------+------------+-------+---------------+-------------+---------+------+-------+--------------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+------------+-------+---------------+-------------+---------+------+-------+--------------------------+
| 1 | SIMPLE | category_part | p2,p4 | range | f_parent_id | f_parent_id | 4 | NULL | 16893 | Using where; Using index |
+----+-------------+---------------+------------+-------+---------------+-------------+---------+------+-------+--------------------------+
1 row in set (0.00 sec)
mysql> select count(*) from category where parent_id = 25;
+----------+
| count(*) |
+----------+
| 2001 |
+----------+
1 row in set (0.01 sec)
mysql> select count(*) from category_part where parent_id = 25;
+----------+
| count(*) |
+----------+
| 2001 |
+----------+
1 row in set (0.00 sec)
mysql> explain select count(*) from category where parent_id = 25;
+----+-------------+----------+------+---------------+-------------+---------+-------+-------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+----------+------+---------------+-------------+---------+-------+-------+-------------+
| 1 | SIMPLE | category | ref | f_parent_id | f_parent_id | 4 | const | 38240 | Using index |
+----+-------------+----------+------+---------------+-------------+---------+-------+-------+-------------+
1 row in set (0.00 sec)
mysql> explain partitions select count(*) from category_part where parent_id = 25;
+----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+-------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+-------------+
| 1 | SIMPLE | category_part | p5 | ref | f_parent_id | f_parent_id | 4 | const | 4647 | Using index |
+----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+-------------+
1 row in set (0.00 sec)
可以看出，扫描的行数大幅度减少
2)、多表内联性能
mysql> select count(*) from category as a inner join parent as b using(parent_id);
+----------+
| count(*) |
+----------+
| 2048000 |
+----------+
1 row in set (0.84 sec)
mysql> select count(*) from category_part as a inner join parent as b using(parent_id);
+----------+
| count(*) |
+----------+
| 2048000 |
+----------+
1 row in set (0.88 sec)
mysql> explain select count(*) from category as a inner join parent as b using(parent_id);
+----+-------------+-------+-------+---------------+-------------+---------+--------------------+-------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+---------------+-------------+---------+--------------------+-------+-------------+
| 1 | SIMPLE | b | index | PRIMARY | PRIMARY | 4 | NULL | 25 | Using index |
| 1 | SIMPLE | a | ref | f_parent_id | f_parent_id | 4 | t_girl.b.parent_id | 81920 | Using index |
+----+-------------+-------+-------+---------------+-------------+---------+--------------------+-------+-------------+
2 rows in set (0.00 sec)
mysql> explain partitions select count(*) from category_part as a inner join parent as b using(parent_id);
+----+-------------+-------+----------------+-------+---------------+-------------+---------+--------------------+------+-------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+----------------+-------+---------------+-------------+---------+--------------------+------+-------------+
| 1 | SIMPLE | b | NULL | index | PRIMARY | PRIMARY | 4 | NULL | 25 | Using index |
| 1 | SIMPLE | a | p1,p2,p3,p4,p5 | ref | f_parent_id | f_parent_id | 4 | t_girl.b.parent_id | 6421 | Using index |
+----+-------------+-------+----------------+-------+---------------+-------------+---------+--------------------+------+-------------+
2 rows in set (0.00 sec)
可以看出，扫描的行数大幅度减少
mysql> explain select count(*) from category as a inner join parent as b using(parent_id) where a.parent_id =19;
+----+-------------+-------+-------+---------------+-------------+---------+-------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+---------------+-------------+---------+-------+------+-------------+
| 1 | SIMPLE | b | const | PRIMARY | PRIMARY | 4 | const | 1 | Using index |
| 1 | SIMPLE | a | ref | f_parent_id | f_parent_id | 4 | const | 6746 | Using index |
+----+-------------+-------+-------+---------------+-------------+---------+-------+------+-------------+
2 rows in set (0.00 sec)
mysql> explain partitions select count(*) from category_part as a inner join parent as b using(parent_id) where a.parent_id =19;
+----+-------------+-------+------------+-------+---------------+-------------+---------+-------+------+-------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+------------+-------+---------------+-------------+---------+-------+------+-------------+
| 1 | SIMPLE | b | NULL | const | PRIMARY | PRIMARY | 4 | const | 1 | Using index |
| 1 | SIMPLE | a | p5 | ref | f_parent_id | f_parent_id | 4 | const | 5203 | Using index |
+----+-------------+-------+------------+-------+---------------+-------------+---------+-------+------+-------------+
2 rows in set (0.00 sec)
由以上数据可以看出，数据越大，查询性能提升的越明显！
2、下来看看写性能
mysql> insert into category(cname,parent_id) values ('Test',1);
Query OK, 1 row affected (0.01 sec)
mysql> insert into category_part(cname,parent_id) values ('Test',1);
Query OK, 1 row affected (0.00 sec)
mysql> select * from category into outfile '/tmp/a.txt';
ERROR 1086 (HY000): File '/tmp/a.txt' already exists
mysql> select * from category into outfile '/tmp/test.dat';
Query OK, 2048005 rows affected (2.82 sec)
mysql> truncate table category;
Query OK, 0 rows affected (0.06 sec)
mysql> truncate table category_part;
Query OK, 2048005 rows affected (0.10 sec)
mysql> load data infile '/tmp/test.dat' into table category;
Query OK, 2048005 rows affected (17.67 sec)
Records: 2048005 Deleted: 0 Skipped: 0 Warnings: 0
mysql> load data infile '/tmp/test.dat' into table category_part;
Query OK, 2048005 rows affected (21.62 sec)
Records: 2048005 Deleted: 0 Skipped: 0 Warnings: 0
可以看出，写性能损失不了多少。牺牲了少许写的性能却大幅度提高了查询的性能，这个是值得的。
如果我有什么说的不对的地方，欢迎各位提意见！MSN:yueliangdao0608@gmail.com |