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

我正在看到以下结果:

我试着添加单独的索引中使用的每一列join,where并且order by,但是仍然使用临时文件.

我不想优化它,但偶尔会导致错误,只能由托管服务提供商修复: Can't create/write to file '/mysql-temp/#sql_64e0_0.MYD' (Errcode: 17)

最大的表是菜单项(6,867),然后是图像(944),菜单(85),场地(79).

UPD:删除ORDER BY不使用临时文件

Answer 1

尝试更改查询以将主 JOIN 逻辑放入子查询中，并查看 EXPLAIN 是否执行得更好：

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，但我很好奇为您解释结果。