下面我们为表t2创建一个索引：
[SQL] 纯文本查看 复制代码
001002003004005006007008009010011
| mysql> createindexin_id ont2(id);Query OK, 0 rowsaffected (0.01 sec)Records: 0 Duplicates: 0 Warnings: 0
mysql> show indexfromt2;+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+| Table| Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null| Index_type | Comment |+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+| t2 | 1 | in_id | 1 | id | A | NULL| NULL| NULL| YES | BTREE | |+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+1 row inset(0.00 sec) |
并插入1000万行的数据。
然后再用：
[SQL] 纯文本查看 复制代码
001
| explain select* fromt2 whereid=1; |
或者
[SQL] 纯文本查看 复制代码
001
| descselect* fromt2 whereid=1; |
查询其影响行数。决定其是否需要优化
http://www.sodu666.com/ZhuShenQi/
http://tieba.sodu666.com/
下面我们为表t2创建一个索引：
[SQL] 纯文本查看 复制代码
001002003004005006007008009010011
| mysql> createindexin_id ont2(id);Query OK, 0 rowsaffected (0.01 sec)Records: 0 Duplicates: 0 Warnings: 0
mysql> show indexfromt2;+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+| Table| Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null| Index_type | Comment |+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+| t2 | 1 | in_id | 1 | id | A | NULL| NULL| NULL| YES | BTREE | |+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+1 row inset(0.00 sec) |
并插入1000万行的数据。
然后再用：
[SQL] 纯文本查看 复制代码
001
| explain select* fromt2 whereid=1; |
或者
[SQL] 纯文本查看 复制代码
001
| descselect* fromt2 whereid=1; |
查询其影响行数。决定其是否需要优化
http://www.sodu666.com/ZhuShenQi/
http://tieba.sodu666.com/
