加速OpenCart中的MySQL查询
I don't know that this is a good question or not, but I have this query in one of my module:
SELECT * FROM `product` WHERE upc IN (
SELECT `upc` FROM `product` WHERE `upc` <> '' GROUP BY `upc` HAVING COUNT(*) > 1)
ORDER BY `upc`
the product table is quite big and this query takes about 20 mins to be executed.
I am not a big MySQL expert, but it is possible to speed up this query?
My second heavy query is an UPDATE query:
UPDATE `product` SET `quantity` = '0' WHERE `sku` IN ( SELECT `id_xml_prd` FROM `ixml_prd_map` WHERE `id_xml` = '8' );
Current indexes on the product table:
And on the ixml_prd_map:
我不知道这是一个好问题,但我在我的一个模块中有这个查询 : p>
SELECT * FROM`product` WHERE upc IN(
SELECT`upc` FROM`product` WHERE`upc`&lt;&gt;''GROUP BY`upcc` HADING COUNT(*)&gt; 1)
ORDER BY`upc`
code> pre>
产品表非常大,此查询需要大约20分钟才能执行。 p>
我不是一个大的MySQL专家,但是可以加快这个查询的速度吗? p>
我的第二个重要查询是UPDATE查询:
更新`product` SET`quedity ='0'WHERE`sku`IN(SELECT`id_xml_prd` FROM`ixml_prd_map` WHERE`id_xml` ='8'); \ n code> pre>
产品表上的当前索引: p>
在ixml_prd_map上: p>
You can modify your query with WHERE EXISTS
like below instead of having a IN
clause with a subquery.
SELECT * FROM `product` p
WHERE EXISTS (
SELECT 1 FROM
`product`
WHERE `upc` <> '' AND `upc` = p.`upc`
GROUP BY `upc`
HAVING COUNT(*) > 1)
ORDER BY `upc`;
Also you would want to have index on upc
column.
Perform a normal update join
query rather than having a IN
subquery
UPDATE `product` p
JOIN `ixml_prd_map` i ON p.`sku` = i.`id_xml_prd`
AND i.`id_xml` = '8'
SET p.`quantity` = '0';
Also for this UPDATE
query to be faster have an index on id_xml_prd
and id_xml
column ON ixml_prd_map
table.