我有一个疑问 其中 8 个连接中的每一个单独需要 0.0007 秒，但是当我将它们组合起来时，查询所需的时间呈指数级增长，最终查询时间为 3 秒。
基本上，我有一种灵活的方式来请求带有附加字段的 field 。前三个字段看起来相当不错，但后来我注意到当我达到 7 时，它需要很长的时间。 我随机化了附加字段的顺序，但事实证明添加什么字段并不重要。
无附加字段[0.52 毫秒]
SELECT
`v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags
FROM
`listing_venue` AS `v`
INNER JOIN
`listing_venue_tag_rel` AS `vtr` ON vtr.venue_id = v.venue_id WHERE (v.venue_id = 79) AND (v.published = 1)
GROUP BY
`venue_id`
1 个附加字段 [0.72 毫秒]
SELECT
`v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags, `addressvalue`.`value` AS `address`
FROM
`listing_venue` AS `v`
INNER JOIN
`listing_venue_tag_rel` AS `vtr` ON vtr.venue_id = v.venue_id
INNER JOIN
`listing_field` AS `addressfield`
LEFT JOIN
`listing_venue_field_rel` AS `addressvalue` ON addressvalue.venue_id = v.venue_id AND addressvalue.field_id = addressfield.field_id
WHERE
(v.venue_id = 79) AND (v.published = 1) AND (addressfield.field_nm = 'address')
GROUP BY
`venue_id`
2 个附加字段 [1.42 毫秒]
SELECT `v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags, `addressvalue`.`value` AS `address`, `address_zhvalue`.`value` AS `address_zh` FROM `listing_venue` AS `v` INNER JOIN `listing_venue_tag_rel` AS `vtr` ON vtr.venue_id = v.venue_id INNER JOIN `listing_field` AS `addressfield` LEFT JOIN `listing_venue_field_rel` AS `addressvalue` ON addressvalue.venue_id = v.venue_id AND addressvalue.field_id = addressfield.field_id INNER JOIN `listing_field` AS `address_zhfield` LEFT JOIN `listing_venue_field_rel` AS `address_zhvalue` ON address_zhvalue.venue_id = v.venue_id AND address_zhvalue.field_id = address_zhfield.field_id WHERE (v.venue_id = 79) AND (v.published = 1) AND (addressfield.field_nm = 'address') AND (address_zhfield.field_nm = 'address_zh') GROUP BY `venue_id`
3 -> 1.13 毫秒
SELECT `v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags, `addressvalue`.`value` AS `address`, `address_zhvalue`.`value` AS `address_zh`, `address_nearvalue`.`value` AS `address_near` FROM `listing_venue` AS `v` INNER JOIN `listing_venue_tag_rel` AS `vtr` ON vtr.venue_id = v.venue_id INNER JOIN `listing_field` AS `addressfield` LEFT JOIN `listing_venue_field_rel` AS `addressvalue` ON addressvalue.venue_id = v.venue_id AND addressvalue.field_id = addressfield.field_id INNER JOIN `listing_field` AS `address_zhfield` LEFT JOIN `listing_venue_field_rel` AS `address_zhvalue` ON address_zhvalue.venue_id = v.venue_id AND address_zhvalue.field_id = address_zhfield.field_id INNER JOIN `listing_field` AS `address_nearfield` LEFT JOIN `listing_venue_field_rel` AS `address_nearvalue` ON address_nearvalue.venue_id = v.venue_id AND address_nearvalue.field_id = address_nearfield.field_id WHERE (v.venue_id = 79) AND (v.published = 1) AND (addressfield.field_nm = 'address') AND (address_zhfield.field_nm = 'address_zh') AND (address_nearfield.field_nm = 'address_near') GROUP BY `venue_id`
4 -> 1.94 毫秒
SELECT `v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags, `addressvalue`.`value` AS `address`, `address_zhvalue`.`value` AS `address_zh`, `address_nearvalue`.`value` AS `address_near`, `phone_numbervalue`.`value` AS `phone_number` FROM `listing_venue` AS `v` INNER JOIN `listing_venue_tag_rel` AS `vtr` ON vtr.venue_id = v.venue_id INNER JOIN `listing_field` AS `addressfield` LEFT JOIN `listing_venue_field_rel` AS `addressvalue` ON addressvalue.venue_id = v.venue_id AND addressvalue.field_id = addressfield.field_id INNER JOIN `listing_field` AS `address_zhfield` LEFT JOIN `listing_venue_field_rel` AS `address_zhvalue` ON address_zhvalue.venue_id = v.venue_id AND address_zhvalue.field_id = address_zhfield.field_id INNER JOIN `listing_field` AS `address_nearfield` LEFT JOIN `listing_venue_field_rel` AS `address_nearvalue` ON address_nearvalue.venue_id = v.venue_id AND address_nearvalue.field_id = address_nearfield.field_id INNER JOIN `listing_field` AS `phone_numberfield` LEFT JOIN `listing_venue_field_rel` AS `phone_numbervalue` ON phone_numbervalue.venue_id = v.venue_id AND phone_numbervalue.field_id = phone_numberfield.field_id WHERE (v.venue_id = 79) AND (v.published = 1) AND (addressfield.field_nm = 'address') AND (address_zhfield.field_nm = 'address_zh') AND (address_nearfield.field_nm = 'address_near') AND (phone_numberfield.field_nm = 'phone_number') GROUP BY `venue_id`
5->9.7 毫秒
SELECT `v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags, `addressvalue`.`value` AS `address`, `address_zhvalue`.`value` AS `address_zh`, `address_nearvalue`.`value` AS `address_near`, `phone_numbervalue`.`value` AS `phone_number`, `websitevalue`.`value` AS `website` FROM `listing_venue` AS `v` INNER JOIN `listing_venue_tag_rel` AS `vtr` ON vtr.venue_id = v.venue_id INNER JOIN `listing_field` AS `addressfield` LEFT JOIN `listing_venue_field_rel` AS `addressvalue` ON addressvalue.venue_id = v.venue_id AND addressvalue.field_id = addressfield.field_id INNER JOIN `listing_field` AS `address_zhfield` LEFT JOIN `listing_venue_field_rel` AS `address_zhvalue` ON address_zhvalue.venue_id = v.venue_id AND address_zhvalue.field_id = address_zhfield.field_id INNER JOIN `listing_field` AS `address_nearfield` LEFT JOIN `listing_venue_field_rel` AS `address_nearvalue` ON address_nearvalue.venue_id = v.venue_id AND address_nearvalue.field_id = address_nearfield.field_id INNER JOIN `listing_field` AS `phone_numberfield` LEFT JOIN `listing_venue_field_rel` AS `phone_numbervalue` ON phone_numbervalue.venue_id = v.venue_id AND phone_numbervalue.field_id = phone_numberfield.field_id INNER JOIN `listing_field` AS `websitefield` LEFT JOIN `listing_venue_field_rel` AS `websitevalue` ON websitevalue.venue_id = v.venue_id AND websitevalue.field_id = websitefield.field_id WHERE (v.venue_id = 79) AND (v.published = 1) AND (addressfield.field_nm = 'address') AND (address_zhfield.field_nm = 'address_zh') AND (address_nearfield.field_nm = 'address_near') AND (phone_numberfield.field_nm = 'phone_number') AND (websitefield.field_nm = 'website') GROUP BY `venue_id`
6 -> 230.52 毫秒
SELECT `v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags, `addressvalue`.`value` AS `address`, `address_zhvalue`.`value` AS `address_zh`, `address_nearvalue`.`value` AS `address_near`, `phone_numbervalue`.`value` AS `phone_number`, `websitevalue`.`value` AS `website`, `price_maxvalue`.`value` AS `price_max` FROM `listing_venue` AS `v` INNER JOIN `listing_venue_tag_rel` AS `vtr` ON vtr.venue_id = v.venue_id INNER JOIN `listing_field` AS `addressfield` LEFT JOIN `listing_venue_field_rel` AS `addressvalue` ON addressvalue.venue_id = v.venue_id AND addressvalue.field_id = addressfield.field_id INNER JOIN `listing_field` AS `address_zhfield` LEFT JOIN `listing_venue_field_rel` AS `address_zhvalue` ON address_zhvalue.venue_id = v.venue_id AND address_zhvalue.field_id = address_zhfield.field_id INNER JOIN `listing_field` AS `address_nearfield` LEFT JOIN `listing_venue_field_rel` AS `address_nearvalue` ON address_nearvalue.venue_id = v.venue_id AND address_nearvalue.field_id = address_nearfield.field_id INNER JOIN `listing_field` AS `phone_numberfield` LEFT JOIN `listing_venue_field_rel` AS `phone_numbervalue` ON phone_numbervalue.venue_id = v.venue_id AND phone_numbervalue.field_id = phone_numberfield.field_id INNER JOIN `listing_field` AS `websitefield` LEFT JOIN `listing_venue_field_rel` AS `websitevalue` ON websitevalue.venue_id = v.venue_id AND websitevalue.field_id = websitefield.field_id INNER JOIN `listing_field` AS `price_maxfield` LEFT JOIN `listing_venue_field_rel` AS `price_maxvalue` ON price_maxvalue.venue_id = v.venue_id AND price_maxvalue.field_id = price_maxfield.field_id WHERE (v.venue_id = 79) AND (v.published = 1) AND (addressfield.field_nm = 'address') AND (address_zhfield.field_nm = 'address_zh') AND (address_nearfield.field_nm = 'address_near') AND (phone_numberfield.field_nm = 'phone_number') AND (websitefield.field_nm = 'website') AND (price_maxfield.field_nm = 'price_max') GROUP BY `venue_id`
7-> 3375.29 毫秒
SELECT
`v`.`venue_id`, `v`.`venue_nm`, GROUP_CONCAT(DISTINCT vtr.tag_id SEPARATOR ",") tags, `addressvalue`.`value` AS `address`, `address_zhvalue`.`value` AS `address_zh`, `address_nearvalue`.`value` AS `address_near`, `phone_numbervalue`.`value` AS `phone_number`, `websitevalue`.`value` AS `website`, `price_maxvalue`.`value` AS `price_max`, `price_minvalue`.`value` AS `price_min`
FROM
`listing_venue` AS `v`
INNER JOIN
`listing_venue_tag_rel` AS `vtr`
ON
vtr.venue_id = v.venue_id
INNER JOIN
`listing_field` AS `addressfield`
LEFT JOIN
`listing_venue_field_rel` AS `addressvalue`
ON
addressvalue.venue_id = v.venue_id AND addressvalue.field_id = addressfield.field_id
INNER JOIN
`listing_field` AS `address_zhfield`
LEFT JOIN
`listing_venue_field_rel` AS `address_zhvalue`
ON
address_zhvalue.venue_id = v.venue_id AND address_zhvalue.field_id = address_zhfield.field_id
INNER JOIN
`listing_field` AS `address_nearfield`
LEFT JOIN
`listing_venue_field_rel` AS `address_nearvalue`
ON
address_nearvalue.venue_id = v.venue_id AND address_nearvalue.field_id = address_nearfield.field_id
INNER JOIN
`listing_field` AS `phone_numberfield`
LEFT JOIN
`listing_venue_field_rel` AS `phone_numbervalue`
ON
phone_numbervalue.venue_id = v.venue_id AND phone_numbervalue.field_id = phone_numberfield.field_id
INNER JOIN
`listing_field` AS `websitefield`
LEFT JOIN
`listing_venue_field_rel` AS `websitevalue`
ON
websitevalue.venue_id = v.venue_id AND websitevalue.field_id = websitefield.field_id
INNER JOIN
`listing_field` AS `price_maxfield`
LEFT JOIN
`listing_venue_field_rel` AS `price_maxvalue`
ON
price_maxvalue.venue_id = v.venue_id AND price_maxvalue.field_id = price_maxfield.field_id
INNER JOIN
`listing_field` AS `price_minfield`
LEFT JOIN
`listing_venue_field_rel` AS `price_minvalue`
ON
price_minvalue.venue_id = v.venue_id AND price_minvalue.field_id = price_minfield.field_id
WHERE
(v.venue_id = 79)
AND (v.published = 1)
AND (addressfield.field_nm = 'address')
AND (address_zhfield.field_nm = 'address_zh')
AND (address_nearfield.field_nm = 'address_near')
AND (phone_numberfield.field_nm = 'phone_number')
AND (websitefield.field_nm = 'website')
AND (price_maxfield.field_nm = 'price_max')
AND (price_minfield.field_nm = 'price_min') GROUP BY `venue_id`
显然我可以将查询分成 7 个，但我不明白为什么会发生这种奇怪的时间增长。
此外，我不确定我是否使用了正确的连接。字段可能是空的，所以这就是为什么我要加入venue_field_rel...
这是表结构
listing_field:
field_id | field_nm
listing_venue_field_rel
venue_id | field_id| value
listing_venue
venue_id | venue_nm
解释一下
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE v const PRIMARY,item_id_UNIQUE PRIMARY 4 const 1
1 SIMPLE addressfield ALL NULL NULL NULL NULL 7 Using where
1 SIMPLE addressvalue ref field_value_venue,fk_mnc_listing_venue_field_rel_venue_id,fk_mnc_listing_venue_field_rel_field_id field_value_venue 4 const 6 Using index
1 SIMPLE address_zhfield ALL NULL NULL NULL NULL 7 Using where; Using join buffer
1 SIMPLE address_zhvalue ref field_value_venue,fk_mnc_listing_venue_field_rel_venue_id,fk_mnc_listing_venue_field_rel_field_id field_value_venue 4 const 6 Using index
1 SIMPLE address_nearfield ALL NULL NULL NULL NULL 7 Using where; Using join buffer
1 SIMPLE address_nearvalue ref field_value_venue,fk_mnc_listing_venue_field_rel_venue_id,fk_mnc_listing_venue_field_rel_field_id field_value_venue 4 const 6 Using index
1 SIMPLE phone_numberfield ALL NULL NULL NULL NULL 7 Using where; Using join buffer
1 SIMPLE phone_numbervalue ref field_value_venue,fk_mnc_listing_venue_field_rel_venue_id,fk_mnc_listing_venue_field_rel_field_id field_value_venue 4 const 6 Using index
1 SIMPLE websitefield ALL NULL NULL NULL 7 Using where; Using join buffer
1 SIMPLE websitevalue ref field_value_venue,fk_mnc_listing_venue_field_rel_venue_id,fk_mnc_listing_venue_field_rel_field_id field_value_venue 4 const 6 Using index
1 SIMPLE price_maxfield ALL NULL NULL NULL 7 Using where; Using join buffer
1 SIMPLE price_maxvalue ref field_value_venue,fk_mnc_listing_venue_field_rel_venue_id,fk_mnc_listing_venue_field_rel_field_id field_value_venue 4 const 6 Using index
1 SIMPLE price_minfield ALL NULL NULL NULL 7 Using where; Using join buffer
1 SIMPLE price_minvalue ref field_value_venue,fk_mnc_listing_venue_field_rel_venue_id,fk_mnc_listing_venue_field_rel_field_id field_value_venue 4 const 6 Using index
1 SIMPLE vtr ref item_tag,fk_venue_id fk_venue_id 4 const 11 Using index
编辑我“索引唯一”field_nm，这将速度降低到7毫秒
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE v const PRIMARY,item_id_UNIQUE PRIMARY 4 const 1
1 SIMPLE addressfield const field_nm,field_nm_2 field_nm 137 const 1 Using index
1 SIMPLE address_zhfield const field_nm,field_nm_2 field_nm 137 const 1 Using index
1 SIMPLE address_nearfield const field_nm,field_nm_2 field_nm 137 const 1 Using index
1 SIMPLE phone_numberfield const field_nm,field_nm_2 field_nm 137 const 1 Using index
1 SIMPLE websitefield const field_nm,field_nm_2 field_nm 137 const 1 Using index
1 SIMPLE price_maxfield const field_nm,field_nm_2 field_nm 137 const 1 Using index
1 SIMPLE addressvalue ref field_value_venue,... field_value_venue 4 const 7 Using index
1 SIMPLE address_zhvalue ref field_value_venue,... field_value_venue 4 const 7 Using index
1 SIMPLE address_nearvalue ref field_value_venue,... field_value_venue 4 const 7 Using index
1 SIMPLE phone_numbervalue ref field_value_venue,... field_value_venue 4 const 7 Using index
1 SIMPLE websitevalue ref field_value_venue,... field_value_venue 4 const 7 Using index
1 SIMPLE price_maxvalue ref field_value_venue,... field_value_venue 4 const 7 Using index
1 SIMPLE vtr ref item_tag,fk_venue_id fk_venue_id 4 const 17 Using index
但是我确信查询可以进一步优化
最佳答案
我认为您可能在这里进行交叉连接
内连接 listing_field AS address_zhfield 左连接
您没有 ON 子句，因此您会得到与其他所有内容的笛卡尔积，这可能会导致指数级减速。
关于mysql - 添加的联接越多，选择所需的时间就越长，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/4508538/