mysql - 如何使用 INNER JOIN 和 ORDER BY 优化 MySQL 查询

Question

鉴于此查询：

EXPLAIN
SELECT mi.*, i1.sizes as tile_photo_sizes,
       i1.filename as tile_photo_filename,
       v.title_cached as venue_title,
       v.subtitle_cached as venue_subtitle,
       v.slug as venue_slug
FROM menuitems mi
INNER JOIN images i1 ON i1.id = mi.tile_photo_id
INNER JOIN menus m ON m.id = mi.menu_id
INNER JOIN venues v ON v.id = m.venue_id
WHERE NOT m.is_deleted AND v.slug="teplo" AND
      m.is_published AND v.is_published
ORDER BY mi.number ASC

我看到以下结果：

我尝试为 , 和 中使用的每一列添加单独的索引join，where但order by它仍然使用临时文件。

我不想优化它，但有时这会导致只能由托管服务提供商修复的错误： Can't create/write to file '/mysql-temp/#sql_64e0_0.MYD' (Errcode: 17)

最大的表是 menuitems (6,867)，然后是图像 (944)、菜单 (85)、场所 (79)。

UPD：删除 ORDER BY 不使用临时文件

Answer 1

尝试更改您的查询，将主要的 JOIN 逻辑放在子查询中，看看 EXPLAIN 的性能是否更好：

EXPLAIN
SELECT * FROM (
    SELECT mi.*, i1.sizes as tile_photo_sizes,
       i1.filename as tile_photo_filename,
       v.title_cached as venue_title,
       v.subtitle_cached as venue_subtitle,
       v.slug as venue_slug
    FROM menuitems mi
    INNER JOIN images i1 ON i1.id = mi.tile_photo_id
    INNER JOIN menus m ON m.id = mi.menu_id
    INNER JOIN venues v ON v.id = m.venue_id
    WHERE NOT m.is_deleted AND v.slug="teplo" AND
        m.is_published AND v.is_published
) as t
ORDER BY t.number ASC

这可能会执行另一种临时情况，但我对您的 EXPLAIN 结果感到好奇。