Mysql 执行时间相同。@jela在内部联接中使用p1.shop\u id=86或shops.shop\u id=86是否有任何更改？此外，请发布SHOW WARNINGS的输出，以便优化的查询可用。这通过使用外部查询消除内部查询返回的不相关结果来解决问题。我暂时不
Mysql 执行时间相同。@jela在内部联接中使用p1.shop\u id=86或shops.shop\u id=86是否有任何更改？此外，请发布SHOW WARNINGS的输出，以便优化的查询可用。这通过使用外部查询消除内部查询返回的不相关结果来解决问题。我暂时不,mysql,Mysql,执行时间相同。@jela在内部联接中使用p1.shop\u id=86或shops.shop\u id=86是否有任何更改？此外，请发布SHOW WARNINGS的输出，以便优化的查询可用。这通过使用外部查询消除内部查询返回的不相关结果来解决问题。我暂时不提这个问题，希望有人能建议重新构造只返回所需结果的内部查询，并比我的292秒版本执行得更高效。我更改了内部连接条件并删除了WHERE子句。查询在283秒内执行。我想知道如何强制慢速查询正确使用主键。我用您建议的对连接条件的更改更新了原始问题。我
执行时间相同。@jela在内部联接中使用p1.shop\u id=86或shops.shop\u id=86是否有任何更改？此外，请发布SHOW WARNINGS的输出，以便优化的查询可用。这通过使用外部查询消除内部查询返回的不相关结果来解决问题。我暂时不提这个问题，希望有人能建议重新构造只返回所需结果的内部查询，并比我的292秒版本执行得更高效。我更改了内部连接条件并删除了WHERE子句。查询在283秒内执行。我想知道如何强制慢速查询正确使用主键。我用您建议的对连接条件的更改更新了原始问题。我还观察到，查询执行时间似乎取决于products.shop_id等于指定shops.shop_id的products表中的行数。products表中约有34K行products.shop_id=86，执行时间为292秒。对于products.shop_id=50，大约有28K行，执行时间为210秒。对于products.shop_id=175，大约有2K行，执行时间为2.8秒。我不确定如何修改查询以纠正这种行为。由于同一查询的速度存在巨大差异，我的第一个猜测是您的排序缓冲区太小。MySQL的性能在不够大的时候急剧下降。我已经修补了一段时间了。这个查询比我的查询快得多：原始查询为0.13秒，而我的原始查询为3.4秒（在比我以前使用的数据集稍大的数据集上）。我对sxFav.Product\u ID=sex.Product\u ID子句中的
加入sex感到困惑。添加此子句似乎会检索非预期的结果，因为查询的目的是仅检索sex.sex=0
的结果，但该子句还将添加sex.sex=1
的行，只要与sxFav.Product\u ID=sex.Product\u ID
匹配。我验证了这增加了11个原始查询未返回的额外行。从您的查询中删除sxFav.Product_ID=sex.Product_IDsex.sex=1连接产品p感到困惑，因为在创建sxFav时已经发生了此连接，所以我似乎可以从sxFav表中的产品表中选择相关列。删除此子句似乎不会更改执行时间。“我可能误解了这两个条款在做什么。”杰拉，继续在聊天室里说吗？我将继续。我已经在@jela创建了聊天室，这里有一个链接，用于我在聊天室中向您提到的复杂sqlvariables问题。。。
SET @num :=0, @current_shop_id := NULL, @current_product_id := NULL;
#this query limits the results of the query within it by row number (so that only 250 products get displayed per store)
SELECT * FROM (
#this query adds row numbers to the query within it
SELECT *, @num := IF( @current_shop_id = shop_id, IF(@current_product_id=product_id,@num,@num+1), 0) AS row_number, @current_shop_id := shop_id AS shop_dummy, @current_product_id := product_id AS product_dummy FROM (
SELECT shop, shops.shop_id AS
shop_id, p1.product_id AS
product_id
FROM products p1 LEFT JOIN #this LEFT JOIN gets the favorites count for each product
(
SELECT fav3.product_id AS product_id, SUM(CASE
WHEN fav3.current = 1 AND fav3.closeted = 1 THEN 1
WHEN fav3.current = 1 AND fav3.closeted = 0 THEN -1
ELSE 0
END) AS favorites_count
FROM favorites fav3
GROUP BY fav3.product_id
) AS fav4 ON p1.product_id=fav4.product_id
INNER JOIN sex ON sex.product_id=p1.product_id AND
sex.sex=0 AND
sex.date >= SUBDATE(NOW(),INTERVAL 1 DAY)
INNER JOIN shops ON shops.shop_id = p1.shop_id
ORDER BY shop, sex.DATE, product_id
) AS testtable
) AS rowed_results WHERE
rowed_results.row_number>=0 AND
rowed_results.row_number<(7)
SET @num :=0, @current_shop_id := NULL, @current_product_id := NULL;
#this query limits the results of the query within it by row number (so that only 250 products get displayed per store)
SELECT * FROM (
#this query adds row numbers to the query within it
SELECT *, @num := IF( @current_shop_id = shop_id, IF(@current_product_id=product_id,@num,@num+1), 0) AS row_number, @current_shop_id := shop_id AS shop_dummy, @current_product_id := product_id AS product_dummy FROM (
SELECT shop, shops.shop_id AS
shop_id, p1.product_id AS
product_id
FROM products p1 LEFT JOIN #this LEFT JOIN gets the favorites count for each product
(
SELECT fav3.product_id AS product_id, SUM(CASE
WHEN fav3.current = 1 AND fav3.closeted = 1 THEN 1
WHEN fav3.current = 1 AND fav3.closeted = 0 THEN -1
ELSE 0
END) AS favorites_count
FROM favorites fav3
GROUP BY fav3.product_id
) AS fav4 ON p1.product_id=fav4.product_id
INNER JOIN sex ON sex.product_id=p1.product_id AND
sex.sex=0 AND
sex.date >= SUBDATE(NOW(),INTERVAL 1 DAY)
INNER JOIN shops ON shops.shop_id = p1.shop_id AND
shops.shop_id=86
ORDER BY shop, sex.DATE, product_id
) AS testtable
) AS rowed_results WHERE
rowed_results.row_number>=0 AND
rowed_results.row_number<(7)
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 1203 100.00 Using where
2 DERIVED <derived3> ALL NULL NULL NULL NULL 1203 100.00
3 DERIVED sex ALL product_id_2,product_id NULL NULL NULL 526846 75.00 Using where; Using temporary; Using filesort
3 DERIVED p1 eq_ref PRIMARY,shop_id,shop_id_2,product_id,shop_id_3 PRIMARY 4 mydatabase.sex.product_id 1 100.00
3 DERIVED <derived4> ALL NULL NULL NULL NULL 14752 100.00
3 DERIVED shops eq_ref PRIMARY PRIMARY 4 mydatabase.p1.shop_id 1 100.00
4 DERIVED fav3 ALL NULL NULL NULL NULL 15356 100.00 Using temporary; Using filesort
-----+
| Note | 1003 | select `rowed_results`.`shop` AS `shop`,`rowed_results`.`shop_id` AS `shop_id`,`rowed_results`.`product_id` AS `product_id`,`rowed_results`.`row_number` AS `row_number`,`rowed_results`.`shop_dummy` AS `shop_dummy`,`rowed_results`.`product_dummy` AS `product_dummy` from (select `testtable`.`shop` AS `shop`,`testtable`.`shop_id` AS `shop_id`,`testtable`.`product_id` AS `product_id`,(@num:=if(((@current_shop_id) = `testtable`.`shop_id`),if(((@current_product_id) = `testtable`.`product_id`),(@num),((@num) + 1)),0)) AS `row_number`,(@current_shop_id:=`testtable`.`shop_id`) AS `shop_dummy`,(@current_product_id:=`testtable`.`product_id`) AS `product_dummy` from (select `mydatabase`.`shops`.`shop` AS `shop`,`mydatabase`.`shops`.`shop_id` AS `shop_id`,`mydatabase`.`p1`.`product_id` AS `product_id` from `mydatabase`.`products` `p1` left join (select `mydatabase`.`fav3`.`product_id` AS `product_id`,sum((case when ((`mydatabase`.`fav3`.`current` = 1) and (`mydatabase`.`fav3`.`closeted` = 1)) then 1 when ((`mydatabase`.`fav3`.`current` = 1) and (`mydatabase`.`fav3`.`closeted` = 0)) then -(1) else 0 end)) AS `favorites_count` from `mydatabase`.`favorites` `fav3` group by `mydatabase`.`fav3`.`product_id`) `fav4` on(((`mydatabase`.`p1`.`product_id` = `mydatabase`.`sex`.`product_id`) and (`fav4`.`product_id` = `mydatabase`.`sex`.`product_id`))) join `mydatabase`.`sex` join `mydatabase`.`shops` where ((`mydatabase`.`sex`.`sex` = 0) and (`mydatabase`.`p1`.`product_id` = `mydatabase`.`sex`.`product_id`) and (`mydatabase`.`shops`.`shop_id` = `mydatabase`.`p1`.`shop_id`) and (`mydatabase`.`sex`.`date` >= (now() - interval 1 day))) order by `mydatabase`.`shops`.`shop`,`mydatabase`.`sex`.`date`,`mydatabase`.`p1`.`product_id`) `testtable`) `rowed_results` where ((`rowed_results`.`row_number` >= 0) and (`rowed_results`.`row_number` < 7)) |
+------
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 36 100.00 Using where
2 DERIVED <derived3> ALL NULL NULL NULL NULL 36 100.00
3 DERIVED shops const PRIMARY PRIMARY 4 1 100.00 Using temporary; Using filesort
3 DERIVED p1 ref PRIMARY,shop_id,shop_id_2,product_id,shop_id_3 shop_id 4 11799 100.00
3 DERIVED <derived4> ALL NULL NULL NULL NULL 14752 100.00
3 DERIVED sex eq_ref product_id_2,product_id product_id_2 5 mydatabase.p1.product_id 1 100.00 Using where
4 DERIVED fav3 ALL NULL NULL NULL NULL 15356 100.00 Using temporary; Using filesort
----+
| Note | 1003 | select `rowed_results`.`shop` AS `shop`,`rowed_results`.`shop_id` AS `shop_id`,`rowed_results`.`product_id` AS `product_id`,`rowed_results`.`row_number` AS `row_number`,`rowed_results`.`shop_dummy` AS `shop_dummy`,`rowed_results`.`product_dummy` AS `product_dummy` from (select `testtable`.`shop` AS `shop`,`testtable`.`shop_id` AS `shop_id`,`testtable`.`product_id` AS `product_id`,(@num:=if(((@current_shop_id) = `testtable`.`shop_id`),if(((@current_product_id) = `testtable`.`product_id`),(@num),((@num) + 1)),0)) AS `row_number`,(@current_shop_id:=`testtable`.`shop_id`) AS `shop_dummy`,(@current_product_id:=`testtable`.`product_id`) AS `product_dummy` from (select 'shop.nordstrom.com' AS `shop`,'86' AS `shop_id`,`mydatabase`.`p1`.`product_id` AS `product_id` from `mydatabase`.`products` `p1` left join (select `mydatabase`.`fav3`.`product_id` AS `product_id`,sum((case when ((`mydatabase`.`fav3`.`current` = 1) and (`mydatabase`.`fav3`.`closeted` = 1)) then 1 when ((`mydatabase`.`fav3`.`current` = 1) and (`mydatabase`.`fav3`.`closeted` = 0)) then -(1) else 0 end)) AS `favorites_count` from `mydatabase`.`favorites` `fav3` group by `mydatabase`.`fav3`.`product_id`) `fav4` on(((`fav4`.`product_id` = `mydatabase`.`p1`.`product_id`) and (`mydatabase`.`sex`.`product_id` = `mydatabase`.`p1`.`product_id`))) join `mydatabase`.`sex` join `mydatabase`.`shops` where ((`mydatabase`.`sex`.`sex` = 0) and (`mydatabase`.`sex`.`product_id` = `mydatabase`.`p1`.`product_id`) and (`mydatabase`.`p1`.`shop_id` = 86) and (`mydatabase`.`sex`.`date` >= (now() - interval 1 day))) order by 'shop.nordstrom.com',`mydatabase`.`sex`.`date`,`mydatabase`.`p1`.`product_id`) `testtable`) `rowed_results` where ((`rowed_results`.`row_number` >= 0) and (`rowed_results`.`row_number` < 7)) |
+-----
Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop PRIMARY BTREE Yes No shop_id 163 A
SET @num :=0, @current_shop_id := NULL, @current_product_id := NULL;
#this query limits the results of the query within it by row number (so that only 250 products get displayed per store)
SELECT * FROM (
#this query adds row numbers to the query within it
SELECT *, @num := IF( @current_shop_id = shop_id, IF(@current_product_id=product_id,@num,@num+1), 0) AS row_number, @current_shop_id := shop_id AS shop_dummy, @current_product_id := product_id AS product_dummy FROM (
SELECT shop, shops.shop_id AS
shop_id, p1.product_id AS
product_id
FROM products p1 LEFT JOIN #this LEFT JOIN gets the favorites count for each product
(
SELECT fav3.product_id AS product_id, SUM(CASE
WHEN fav3.current = 1 AND fav3.closeted = 1 THEN 1
WHEN fav3.current = 1 AND fav3.closeted = 0 THEN -1
ELSE 0
END) AS favorites_count
FROM favorites fav3
GROUP BY fav3.product_id
) AS fav4 ON p1.product_id=fav4.product_id
INNER JOIN sex ON sex.product_id=p1.product_id AND sex.sex=0
INNER JOIN shops ON shops.shop_id = p1.shop_id
WHERE sex.date >= SUBDATE(NOW(),INTERVAL 1 DAY)
ORDER BY shop, sex.DATE, product_id
) AS testtable
) AS rowed_results WHERE
rowed_results.row_number>=0 AND
rowed_results.row_number<(7) AND
rowed_results.shop_dummy=86;
SELECT
PreQuery.*,
@num := IF( @current_shop_id = PreQuery.shop_id, @num +1, 1 ) AS RowPerShop,
@current_shop_id := PreQuery.shop_id AS shop_dummy
from
( SELECT
sxFav.product_id,
sxFav.shop_id,
sxFav.Favorites_Count
from
( SELECT
sex.product_id,
MAX( p.shop_id ) shop_id,
SUM( CASE WHEN F.current = 1 AND F.closeted = 1 THEN 1
WHEN F.current = 1 AND F.closeted = 0 THEN -1
ELSE 0 END ) AS favorites_count
from
sex
JOIN products p
ON sex.Product_ID = p.Product_ID
LEFT JOIN Favorites F
ON sex.product_id = F.product_ID
where
sex.date >= subdate( now(), interval 1 day)
and sex.sex = 0
group by
sex.product_id ) sxFav
JOIN sex
ON sxFav.Product_ID = sex.Product_ID
JOIN products p
ON sxFav.Product_ID = p.Product_ID
order by
sxFav.shop_id,
sex.date,
sxFav.product_id ) PreQuery,
( select @num :=0,
@current_shop_id := 0 ) as SQLVars
select * from ( entire query above ) where RowPerShop between 1 and 7
RowPerShop between RowsPerPage*PageYouAreShowing and RowsPerPage*(PageYouAreShowing +1)
....
INNER JOIN shops ON shops.shop_id = p1.shop_id AND shops.shop_id=86
....
...
INNER JOIN shops ON shops.shop_id = p1.shop_id
AND sex.date >= SUBDATE(NOW(),INTERVAL 1 DAY)
...
3 DERIVED p1 eq_ref PRIMARY,shop_id,shop_id_2,product_id,shop_id_3 PRIMARY 4 mydatabase.sex.product_id 1 100.00
3 DERIVED p1 ref PRIMARY,shop_id,shop_id_2,product_id,shop_id_3 shop_id 4 11799 100.00