MySQL - 非常慢的查询(在一张表上简单选择)

Question

冷运行此查询需要 200 - 400 毫秒。当我重新运行它时，它是即时的。但我认为冷查询非常慢。我可以做些什么来提高速度？数据库在具有足够 DDR2 内存的 core2duo 3,16ghz 上运行。

SELECT * from item_has_category
        WHERE category_category_id = 18
        LIMIT 10 OFFSET 2000

表中没有太多条目

        mysql> SELECT COUNT(*) from item_has_category;
        +----------+
        | COUNT(*) |
        +----------+
        |   111611 |
        +----------+

我的类型是:

        mysql> describe item_has_category;
        +----------------------+---------+------+-----+---------+-------+
        | Field                | Type    | Null | Key | Default | Extra |
        +----------------------+---------+------+-----+---------+-------+
        | item_item_id         | int(11) | NO   | MUL | NULL    |       |
        | category_category_id | int(11) | NO   | MUL | NULL    |       |
        +----------------------+---------+------+-----+---------+-------+

索引是:

        mysql> SHOW INDEX from item_has_category;
        +-------------------+------------+----------------------+--------------+----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
        | Table             | Non_unique | Key_name             | Seq_in_index | Column_name          | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
        +-------------------+------------+----------------------+--------------+----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
        | item_has_category |          1 | category_category_id |            1 | category_category_id | A         |          56 |     NULL | NULL   |      | BTREE      |         |               |
        | item_has_category |          1 | item_item_id_2       |            1 | item_item_id         | A         |      111855 |     NULL | NULL   |      | BTREE      |         |               |
        +-------------------+------------+----------------------+--------------+----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

解释:

        mysql> EXPLAIN SELECT * from item_has_category WHERE category_category_id = 18 LIMIT 10,2000;
        +----+-------------+-------------------+------+----------------------+----------------------+---------+-------+------+-------+
        | id | select_type | table             | type | possible_keys        | key                  | key_len | ref   | rows | Extra |
        +----+-------------+-------------------+------+----------------------+----------------------+---------+-------+------+-------+
        |  1 | SIMPLE      | item_has_category | ref  | category_category_id | category_category_id | 4       | const | 2840 |       |
        +----+-------------+-------------------+------+----------------------+----------------------+---------+-------+------+-------+

Answer 1

您可以尝试将其作为存储过程运行，因为它们已被缓存并且可能会为您运行得更快一些。

DELIMITER $$

CREATE PROCEDURE `database_name`.`procedure_name` (
IN category_id INT,
IN rows_limit INT,
IN records_offset INT)
BEGIN
        SELECT * from item_has_category
        WHERE category_category_id = category_id
        LIMIT rows_limit OFFSET records_offset
END

然后调用它

CALL procedure_name(18,10,2000);