Question

我的查询正在执行全表扫描。

mysql> explain select dr.* from iflora_delivery_rules dr where dr.order_end_date >= "2013-05-01 09:28:05" and dr.deactive_date is null and ( (brand_id = 1 and dr.source_code in ( '1.1.1.1' , '1.1.1' , '1.1' , '1' )) or (brand_id = 0 and dr.source_code in ( '1.1.1.1' , '1.1.1' , '1.1' , '1' ))) order by precedence desc,brand_id desc,source_code desc;
+----+-------------+-------+------+---------------+------+---------+------+------+-----------------------------+
| id | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra                       |
+----+-------------+-------+------+---------------+------+---------+------+------+-----------------------------+
|  1 | SIMPLE      | dr    | ALL  | NULL          | NULL | NULL    | NULL |  867 | Using where; Using filesort |
+----+-------------+-------+------+---------------+------+---------+------+------+-----------------------------+
1 row in set (0.00 sec)

我在列brand_id，source_code

上创建了索引

mysql> create index idx_brand_n1 on iflora_delivery_rules(brand_id);
Query OK, 0 rows affected (0.08 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql>  create index idx_source_code_n1 on iflora_delivery_rules(source_code);
Query OK, 0 rows affected (0.09 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> explain select dr.* from iflora_delivery_rules dr where dr.order_end_date >= "2013-05-01 09:28:05" and dr.deactive_date is null and ( (brand_id = 1 and dr.source_code in ( '1.1.1.1' , '1.1.1' , '1.1' , '1' )) or (brand_id = 0 and dr.source_code in ( '1.1.1.1' , '1.1.1' , '1.1' , '1' ))) order by precedence desc,brand_id desc,source_code desc;
+----+-------------+-------+------+---------------------------------+------+---------+------+------+-----------------------------+
| id | select_type | table | type | possible_keys                   | key  | key_len | ref  | rows | Extra                       |
+----+-------------+-------+------+---------------------------------+------+---------+------+------+-----------------------------+
|  1 | SIMPLE      | dr    | ALL  | idx_brand_n1,idx_source_code_n1 | NULL | NULL    | NULL |  867 | Using where; Using filesort |
+----+-------------+-------+------+---------------------------------+------+---------+------+------+-----------------------------+
1 row in set (0.00 sec)

表

mysql> show create table iflora_delivery_rules\G
*************************** 1. row ***************************
       Table: iflora_delivery_rules
Create Table: CREATE TABLE `iflora_delivery_rules` (
  `row_mod` datetime DEFAULT NULL,
  `row_create` datetime DEFAULT NULL,
  `delivery_rule_id` int(11) NOT NULL,
  `source_code` varchar(20) COLLATE latin1_bin DEFAULT NULL,
  `rotation_weight` int(11) DEFAULT NULL,
  `order_start_date` datetime DEFAULT NULL,
  `order_end_date` datetime DEFAULT NULL,
  `order_day_of_week` varchar(7) COLLATE latin1_bin DEFAULT NULL,
  `delivery_start_date` datetime DEFAULT NULL,
  `delivery_end_date` datetime DEFAULT NULL,
  `delivery_day_of_week` varchar(7) COLLATE latin1_bin DEFAULT NULL,
  `charge_type` varchar(50) COLLATE latin1_bin NOT NULL,
  `lead_min_days` int(11) NOT NULL,
  `lead_max_days` int(11) NOT NULL,
  `precedence` decimal(12,4) NOT NULL,
  `charge_name` varchar(255) COLLATE latin1_bin DEFAULT NULL,
  `amount` decimal(8,2) NOT NULL,
  `display_colour` varchar(50) COLLATE latin1_bin DEFAULT NULL,
  `display_long_desc` varchar(100) COLLATE latin1_bin DEFAULT NULL,
  `display_short_desc` varchar(50) COLLATE latin1_bin DEFAULT NULL,
  `exec_country_type` varchar(5) COLLATE latin1_bin NOT NULL,
  `shipping_method_id` int(11) DEFAULT NULL,
  `rule_line_id` varchar(20) COLLATE latin1_bin NOT NULL,
  `deactive_date` datetime DEFAULT NULL,
  `version_id` int(11) DEFAULT NULL,
  `delivery_rule_type` varchar(5) COLLATE latin1_bin DEFAULT NULL,
  `brand_id` int(11) DEFAULT NULL,
  KEY `iflora_delivery_rules_n1` (`shipping_method_id`),
  KEY `idx_exec_country_type_n1` (`exec_country_type`),
  KEY `idx_rotation_weight_n1` (`rotation_weight`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_bin
1 row in set (0.00 sec)

Answer 1

我认为WHERE子句中的OR阻止它使用索引。由于dr.source_code在两种情况下都相同，因此不需要在那里。此查询是等效的，应使用其中一个索引。

select dr.* from iflora_delivery_rules dr
where dr.order_end_date >= "2013-05-01 09:28:05"
and dr.deactive_date is null
and brand_id in (0, 1)
and dr.source_code in ( '1.1.1.1' , '1.1.1' , '1.1' , '1' )
order by precedence desc,brand_id desc,source_code desc;

创建复合索引可能更好：

create index idx_brand_id_source_code_n1 on iflora_delivery_rules(brand_id, source_code);

但由于您在两个字段上都使用IN条件，因此我不确定它是否可以使用此字段。

Answer 2

我试试这个

explain 
SELECT dr.* 
FROM iflora_delivery_rules dr 
WHERE
    dr.brand_id IN(1,0) 
    AND dr.source_code in ( '1.1.1.1' , '1.1.1' , '1.1' , '1' )
    AND dr.order_end_date >= "2013-05-01 09:28:05" 
    AND dr.deactive_date is null 
ORDER BY precedence desc, brand_id desc, source_code desc;

Answer 3

虽然我不认为OR会导致问题，但很容易通过使用UNION来删除它以确认

SELECT dr.* 
FROM iflora_delivery_rules dr 
WHERE dr.order_end_date >= "2013-05-01 09:28:05" 
AND dr.deactive_date IS NULL 
AND brand_id = 1 
AND dr.source_code IN ( '1.1.1.1' , '1.1.1' , '1.1' , '1' )
UNION
SELECT dr.* 
FROM iflora_delivery_rules dr 
WHERE dr.order_end_date >= "2013-05-01 09:28:05" 
AND dr.deactive_date IS NULL 
AND brand_id = 0 
AND dr.source_code IN ( '1.1.1.1' , '1.1.1' , '1.1' , '1' )
ORDER BY precedence DESC,brand_id DESC,source_code DESC

但我怀疑问题可能是您选择的索引。 MySQL将仅在查询中的表上使用一个索引，因此它将选择brand_id或source_code上的索引。然而，在猜测你的例子时，选择这些都不会缩小记录的数量，因此很可能忽略了（如果索引大幅缩小了结果，那么只有MySQL才能使用索引，如果不是那么它忽略索引）。

我很想使用覆盖多列的密钥。至少是brand_id和source_code，很可能也是order_end_date。

查询也在创建索引后执行完全扫描

3 个答案: