[英]MySql Query Optimization to avoid filesort
我希望有人帮助我优化并避免在以下查询中进行文件排序。 附上其说明的屏幕截图
SELECT DISTINCT(storages.id),
IF(admin_approve = 1
OR storage_free_auctions.user_id = 167
OR ISNULL(storage_free_auctions.user_id),
auction_date, NULL) AS auction_date1
FROM user_list_storage
JOIN storages ON storages.id = user_list_storage.storage_id
JOIN states ON states.id = storages.state
LEFT JOIN storage_auctions ON storage_auctions.id = (
SELECT storage_auctions.id FROM storage_auctions
LEFT JOIN storage_free_auctions
ON storage_free_auctions.storage_auctions_id=storage_auctions.id
WHERE storage_auctions.storage_id = storages.id
AND storage_auctions.status = 'Active'
AND ( ISNULL(storage_free_auctions.user_id)
OR admin_approve = 1
OR storage_free_auctions.user_id = 167)
AND CONCAT(auction_date,' ',start_time) >= CURDATE()
ORDER BY auction_date ASC LIMIT 1)
LEFT JOIN storage_free_auctions
ON storage_free_auctions.storage_auctions_id=storage_auctions.id
LEFT JOIN storage_auction_units
ON storage_auction_units.storage_auction_id = storage_auctions.id
AND storage_auction_units.status='Active'
WHERE storages.storage_status = 'Active'
AND user_list_storage.user_id = 167
AND user_list_storage.user_list_id = 3
AND (storage_free_auctions.user_id = 167
OR admin_approve = 1
OR ISNULL(storage_free_auctions.user_id)
OR user_list_storage.user_id = 167)
GROUP BY storages.id
order by auction_date1
解释结果的第一行如下。
id: 1 Select_type: PRIMARY 表: user_list_storage 类型: ref 可能的 键: idx_user_list_id,idx_storage_id,idx_user_id 密钥: idx_user_id key_len: 5 ref: const
行: 64
额外:在哪里使用; 使用临时; 使用文件排序
更换
LEFT JOIN storage_auctions
ON storage_auctions.id= (SELECT storage_auctions.id
FROM storage_auctions
LEFT JOIN storage_free_auctions
ON storage_free_auctions.storage_auctions_id = storage_auctions.id
WHERE storage_auctions.storage_id = storages.id
AND storage_auctions.status = 'Active'
AND (ISNULL(storage_free_auctions.user_id)
OR admin_approve = 1
OR storage_free_auctions.user_id = 167)
AND CONCAT(auction_date,' ',start_time) >= CURDATE() ORDER BY auction_date ASC LIMIT 1)
同
AND EXISTS (SELECT 1
FROM storage_auctions
WHERE storage_auctions.id = storages.id
AND CONCAT(auction_date,' ',start_time) >= CURDATE())
因为您在左联接中的子句是多余的并且之前已经完成,所以您想要的是将来存在具有相同id的记录,对吗?
其余的联接都可以。 它们都基于整数列,如果它们不是主键和runstats,请确保对所有这些id进行索引。
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