source sales_flat_order_dump.sql

analyze table sales_flat_order;

explain  

SELECT `main_table`.* FROM `sales_flat_order` AS `main_table` WHERE (`increment_id` >= 238900 AND `increment_id` <= 238907)

;

+------+-------------+------------+------+-----------------------------------+------+---------+------+--------+-------------+

| id   | select_type | table      | type | possible_keys                     | key  | key_len | ref  | rows   | Extra       |

+------+-------------+------------+------+-----------------------------------+------+---------+------+--------+-------------+

|    1 | SIMPLE      | main_table | ALL  | UNQ_SALES_FLAT_ORDER_INCREMENT_ID | NULL | NULL    | NULL | 260559 | Using where |

+------+-------------+------------+------+-----------------------------------+------+---------+------+--------+-------------+

explain  

SELECT `main_table`.* FROM `sales_flat_order` AS `main_table` WHERE (`increment_id` >= '238900' AND `increment_id` <= '238907')

;

+------+-------------+------------+-------+-----------------------------------+-----------------------------------+---------+------+------+-----------------------+

| id   | select_type | table      | type  | possible_keys                     | key                               | key_len | ref  | rows | Extra                 |

+------+-------------+------------+-------+-----------------------------------+-----------------------------------+---------+------+------+-----------------------+

|    1 | SIMPLE      | main_table | range | UNQ_SALES_FLAT_ORDER_INCREMENT_ID | UNQ_SALES_FLAT_ORDER_INCREMENT_ID | 153     | NULL | 3    | Using index condition |

+------+-------------+------------+-------+-----------------------------------+-----------------------------------+---------+------+------+-----------------------+