Question

我有一个超过100k行的表格，所以下面的查询非常慢（4秒 - 平均）。

SELECT cat1.id AS cat1id, 
    cat1.title_gr AS title, 
    cat1.order

    FROM categories_groups_cat1 AS cat1

    INNER JOIN 
      ( SELECT categories_id, categories_groups_cat1_id FROM
        categories_vs_groups
        GROUP BY categories_groups_cat1_id ) AS vs
    ON vs.categories_groups_cat1_id=cat1.id

    INNER JOIN 
      ( SELECT id, title_gr FROM
        categories
        GROUP BY title_gr ) AS cats
    ON cats.id=vs.categories_id

   INNER JOIN 
      ( SELECT category_gr FROM
        offers
        GROUP BY category_gr ) AS offers
    ON offers.category_gr=cats.title_gr

    GROUP BY cat1.id
    ORDER BY cat1.order ASC

表格提供

`id` int(11) NOT NULL,
`title` text NOT NULL,
`description` text NOT NULL,
`image` text NOT NULL,
`price` float NOT NULL,
`start_price` float NOT NULL,
`brand` text NOT NULL
`category_gr` text NOT NULL

table categories_groups_cat1

`id` int(11) NOT NULL,
`order` int(11) NOT NULL,
`title_gr` text NOT NULL

table categories_vs_groups

`id` int(11) NOT NULL,
`categories_groups_cat1_id` int(11) NOT NULL,
`categories_id` int(11) NOT NULL

表类别

`id` int(11) NOT NULL,
`title_gr` char(255) NOT NULL

我尝试从categories_groups_cat1中选择存在的商品，这就是我使用内部联接的原因。我不知道它是否完全正确。如果有另一个更快（性能）的解决方案，我将不胜感激

Answer 1

您应该避免创建临时表的子查询。这肯定会提高性能。在内存中创建临时表的子查询会导致性能下降，尽量避免使用。

我修改了你的代码。可能存在小的语法错误。

  SELECT cat1.id AS cat1id, 
        cat1.title_gr AS title, 
        cat1.order

        FROM categories_groups_cat1 AS cat1

        INNER JOIN 
          categories_groups_cat1_id  AS vs
        ON vs.categories_groups_cat1_id=cat1.id

        INNER JOIN 

            categories
             AS cats
        ON cats.id=vs.categories_id

       INNER JOIN 

            offers

        ON offers.category_gr=cats.title_gr

        GROUP BY cat1.id,cats.title_gr, offers.category_gr
        ORDER BY cat1.order ASC

内连接慢性能

1 个答案: