php - 缓慢的搜索查询 - 错误的编码，（左连接）

Question

错误的搜索查询正在使我们的网站崩溃。写这个的人计算了每个子类别，然后将它们加在一起以获得主要类别的总数。对于分页 Next、Last、Pages，然后使用 JOIN/INNER JOIN（该页面的所有产品）编写查询。它创建了太多的步骤，从而减慢了一切，直到超时。帮助！

查询摘要：

SELECT COUNT(DISTINCT node.nid) AS cnt FROM 
content_type_product cp 
LEFT JOIN node node ON node.nid = cp.nid 
LEFT JOIN uc_products uc_products ON node.nid = uc_products.nid 
LEFT JOIN users users ON users.uid = node.uid 
LEFT JOIN files ON files.fid = cp.field_product_image_1_value 
LEFT JOIN content_type_product_tags ct ON ct.field_product_product_id_value = cp.nid 
WHERE 
    (
    node.status <> N
    ) 
AND 
    (
    ct.field_product_tag_id_value = N
    ) 
AND 
    (
    cp.field_deleted_value <> N
    ) 
AND 
    (
    cp.field_stock_level_value > N
    ) 
AND EXISTS 
    (
    SELECT scp.nid FROM content_type_store scp 
    LEFT JOIN node snode ON snode.nid = scp.nid 
    LEFT JOIN users susers ON susers.uid = snode.uid 
    WHERE susers.name = users.name 
        AND scp.field_shop_activated_value = 'S' 
        AND scp.field_shop_suspended_value = 'S') 
ORDER BY cp.field_product_last_changed_value DESC;

查询样本：

SELECT count(Distinct node.nid) as cnt 
FROM content_type_product cp 
LEFT JOIN node node ON node.nid = cp.nid 
LEFT JOIN uc_products uc_products ON node.nid = uc_products.nid 
LEFT JOIN users users ON users.uid = node.uid 
LEFT JOIN files ON files.fid = cp.field_product_image_1_value 
LEFT JOIN content_type_product_tags ct ON ct.field_product_product_id_value = cp.nid
WHERE 
    (
    node.status <> 0
    ) 
    AND 
        (
        ct.field_product_tag_id_value = 478
        ) 
    AND 
        (
        cp.field_deleted_value <> 1
        ) 
    AND 
        (
        cp.field_stock_level_value > 0
        ) 
    AND EXISTS 
        (
        SELECT scp.nid FROM content_type_store scp 
        LEFT JOIN node snode on snode.nid = scp.nid 
        LEFT JOIN users susers on susers.uid = snode.uid 
        WHERE susers.name = users.name 
            AND scp.field_shop_activated_value = '1' 
            AND scp.field_shop_suspended_value = '0'
        ) 
    ORDER BY cp.field_product_last_changed_value DESC

Answer 1

这是需要遵循的以下步骤以避免慢查询

1. 首先从节点开始，而不是从内容表开始。
2. 对于内容表加入vid而不是nid
3. 无需在查询中使用distinct和。group by如果您使用的是您的查询有一些连接问题。

SELECT count(Distinct node.nid) as cnt 
FROM node node 
LEFT JOIN content_type_product cp ON cp.vid = node.vid 
LEFT JOIN uc_products uc_products ON node.vid = uc_products.vid 
LEFT JOIN users users ON users.uid = node.uid 
LEFT JOIN files ON files.fid = cp.field_product_image_1_value 
LEFT JOIN content_type_product_tags ct ON ct.field_product_product_id_value = cp.vid
WHERE 
    (
    node.status <> 0
    ) 
    AND 
        (
        ct.field_product_tag_id_value = 478
        ) 
    AND 
        (
        cp.field_deleted_value <> 1
        ) 
    AND 
        (
        cp.field_stock_level_value > 0
        ) 
    AND EXISTS 
        (
        SELECT scp.nid FROM content_type_store scp 
        LEFT JOIN node snode on snode.nid = scp.nid 
        LEFT JOIN users susers on susers.uid = snode.uid 
        WHERE susers.name = users.name 
            AND scp.field_shop_activated_value = '1' 
            AND scp.field_shop_suspended_value = '0'
        ) 
    ORDER BY cp.field_product_last_changed_value DESC

Answer 2

在主表和连接表中添加索引将加快您的查询。