[英]Speed up the query when using multiple joins in mysql
我在需要连接5个表的地方有sql查询。 到目前为止,我已经尝试过此查询。 它正在工作,但需要很长时间。 在这里可以做些什么来优化以下查询?
$select_query = 'select ';
$select_query .= "ROUND((
6371 * ACOS(
COS(RADIANS('.$lat.')) COS(RADIANS(lat)) COS(
RADIANS(lng) - RADIANS('.$lng.')
) + SIN(RADIANS('.$lat.')) * SIN(RADIANS(lat))
)
),2) AS property_distance ,";
$select_query .= "
pro.id as id,
pro.user_id,
pro.category_id,
pro.total_price,
pro.size,
pro.lat,
pro.lng,
pro.city,
pro.city_english,
pro.created_at,
pimg.image as property_images,
pimg.property_id,
pa.property_id,
pa.category_attribute_id,
pa.is_multiple_data,
pa.attribute_value,
ca.category_id,
ca.attribute_name,
ct.category_id,
ct.category_name,
cat.attribute_id,
cat.attribute_label,
cat.locale
FROM
property pro FORCE INDEX (property_index)
left join property_images pimg on pro.id=pimg.property_id
JOIN property_attributes pa ON
pa.property_id = pro.id
left JOIN category_attributes ca ON
ca.id = pa.category_attribute_id
left JOIN category_attributes_translations cat ON
ca.id = cat.attribute_id
left JOIN categories_translation ct ON
pro.category_id = ct.category_id
WHERE pro.is_confirm='1' and pro.status='1' and pro.deal_finish='0' and cat.locale='" . $locale . "' and ct.locale='" . $locale . "'
GROUP BY pro.id HAVING property_distance<=10 ORDER by pro.id DESC";
然后最终运行此查询。
请为我建议优化此查询的正确方法。
在进行任何联接之前,我将修改查询以遍历属性表并消除尽可能多的行。 HAVING子句中有关大圆距离计算结果的条件将要求该计算必须在WHERE子句没有消除的每一行上进行。
我只针对property
表编写查询,如下所示:
SELECT ROUND( ( 6371 * ACOS( COS(RADIANS( :lat ) )
* COS(RADIANS(pro.lat))
* COS(RADIANS(pro.lng) - RADIANS( :lng ) )
+ SIN(RADIANS( :lat ))
* SIN(RADIANS(pro.lat))
)
)
,2) AS property_distance
, pro.id
, pro.user_id
, pro.category_id
, pro.total_price
, pro.size
, pro.lat
, pro.lng
, pro.city
, pro.city_english
, pro.created_at
FROM property pro
WHERE pro.is_confirm = '1'
AND pro.status = '1'
AND pro.deal_finish = '0'
HAVING property_distance <= 10
ORDER
BY pro.id DESC
假设id
在property
表中是唯一的。 这应该能够有效地使用具有前导列deal_finish
, status
和is_confirm
的索引,以消除考虑的某些行。
... ON property (deal_finish,status,is_confirm,...)
设置好之后,我们可以在外部查询中将其作为内联视图(派生表)引用,并且外部查询可以将其联接到其他表。
请注意,如果我们在product_images
和product_attributes
有多个匹配的行,则对两个表进行联接将创建一个半笛卡尔乘积, product_image
每一行与product_attribute
每一行都匹配。 即,从20行product_image
交叉连接到从20行product_attribute
将产生一组400个的行。
SELECT c.*
FROM ( -- inline view query
SELECT ROUND( ( 6371 * ACOS( COS(RADIANS( :lat ) )
* COS(RADIANS(pro.lat))
* COS(RADIANS(pro.lng) - RADIANS( :lng ) )
+ SIN(RADIANS( :lat ))
* SIN(RADIANS(pro.lat))
)
)
,2) AS property_distance
, pro.id
, pro.user_id
, pro.category_id
, pro.total_price
, pro.size
, pro.lat
, pro.lng
, pro.city
, pro.city_english
, pro.created_at
FROM property pro
WHERE pro.is_confirm = '1'
AND pro.status = '1'
AND pro.deal_finish = '0'
HAVING property_distance <= 10
ORDER BY pro.id DESC
) c
LEFT
JOIN product_images pimg
ON pimg.product_id = c.id
ORDER BY c.id DESC
现在,出现了使用GROUP BY
折叠行的整个问题,并且表达式在功能上不依赖于ONLY_FULL_GROUP_BY sql_mode等。
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