Explain SQL statement Performance detection

Typically used to parse how SQL statements are executed, using those keys

Mysql>explain select * FROM table;
+----+-------------+-------+------+---------------+------+---------+------+------+-------+
| ID | Select_type | Table | Type | Possible_keys | Key | Key_len | Ref | Rows | Extra |
+----+-------------+-------+------+---------------+------+---------+------+------+-------+

table           # Displays the table involved in the statement
type            # reflect the quality of the statement, excellent-to-poor: const > Eq_reg > Ref > Range > Indexhe > All
Possible_keys & nbsp #存在表中的所有索引
key              #使用到的索引
key_len          #索引长度, as short as possible
ref              #显示索引的那一列被用到
rows             #语句返回的数据行数
Extra            #语句查询情况的详细信息