Question

我问wrong question所以我会再试一次（对不起）。您不必详细阅读查询，只是为了给您一个想法。

无论如何：有问题的查询是由Doctrine2生成的（我剪切SELECT部分）

FROM
    tbl_story t0_ 
      LEFT JOIN tbl_user t1_ ON t0_.creator_id = t1_.id 
      LEFT JOIN tbl_image t2_  ON t1_.avatar_id = t2_.id 
      LEFT JOIN tbl_image t3_  ON t0_.id = t3_.story_id 
      LEFT JOIN tbl_like t4_ ON t0_.id = t4_.story_id AND (t4_.creator_id = 3) 
      LEFT JOIN tbl_comment t5_ ON t0_.id = t5_.story_id 
      LEFT JOIN tbl_like t6_  ON t5_.id = t6_.comment_id AND (t6_.creator_id = 3) 
      LEFT JOIN tbl_user t7_  ON t5_.creator_id = t7_.id 
      LEFT JOIN tbl_image t8_ ON t7_.avatar_id = t8_.id 
      LEFT JOIN tbl_location_city t9_  ON t0_.city_id = t9_.id 
      LEFT JOIN tbl_location_state t10_ ON t9_.state_id = t10_.id 
      LEFT JOIN tbl_location_country t11_ ON t10_.country_id = t11_.id 
      LEFT JOIN tbl_story t12_ ON t0_.parent_id = t12_.id 
      LEFT JOIN tbl_page t13_ ON t0_.page_id = t13_.id 
      LEFT JOIN tbl_page_type t14_ ON t13_.page_type_id = t14_.id 
      LEFT JOIN tbl_story_tag t25_  ON t0_.id = t25_.story_id 
      LEFT JOIN tbl_tag t15_ ON t15_.id = t25_.tag_id 
      LEFT JOIN tbl_story_linked_user_reference t16_ ON t0_.id = t16_.story_id 
      LEFT JOIN tbl_user t17_ ON t16_.user_id = t17_.id 
      LEFT JOIN tbl_image t18_ ON t17_.avatar_id = t18_.id 
      LEFT JOIN tbl_story t19_  ON t0_.id = t19_.parent_id 
      LEFT JOIN tbl_album t20_ ON t0_.parent_album_id = t20_.id 
      LEFT JOIN tbl_image t21_ ON t20_.id = t21_.album_id 
      LEFT JOIN tbl_image_linked_user t22_ ON t21_.id = t22_.image_id 
      LEFT JOIN tbl_user t23_ ON t22_.user_id = t23_.id 
      LEFT JOIN tbl_image t24_ ON t23_.avatar_id = t24_.id 
WHERE (
    t0_.creator_id = 3 
    OR t0_.id IN 
        (SELECT 
          t26_.id 
        FROM tbl_story t26_ 
          INNER JOIN tbl_story_circle_visibility t28_ ON t26_.id = t28_.story_id 
          INNER JOIN tbl_circle t27_ ON t27_.id = t28_.circle_id 
          INNER JOIN tbl_user_circle_reference t29_ ON t27_.id = t29_.circle_id 
            AND (t29_.user_id = 3))
    OR t0_.is_public = 1
  ) 
  AND t0_.is_draft = 0 
  AND t0_.type IN (0, 3, 2, 21) 
ORDER BY t0_.created_at DESC
LIMIT 7

问题：使用ORDER BY，当tbl_story（主查询）中只有31.000行时，查询需要1.2秒才能执行。如果我删除ORDER BY，它会在6ms内执行，我想所有这些连接需要额外的时间，但仍然无需担心。

我首先thought ORDER BY很慢，但我错了。我试过了

SELECT * FROM `tbl_story` ORDER BY created_at DESC LIMIT 7

（同样但没有连接）并且它在2ms内执行。

我也阅读了其他问题，包括this one，建议删除JOIN个部分。如果我在Doctrine2中可以做到这一点，那可能会有用：

$queryBuilder->select("o.id")->removeLeftJoins()

在我获取ID之后，使用它们克隆原始查询。

如何解决分页问题？

注：

即使我完全删除WHERE子句，查询也会花费相同的1.2秒，因此不会出现问题。

感谢。

Answer 1

我怀疑对type和is_draft进行索引可能不会缩小范围，以便MySQL不会注意到这些索引。

如果你有一个关于creator_id的索引，另一个关于is_public而另一个关于id（我假设你这样做，因为它可能是主要的id），那么这样的3个联合查询可能会有所帮助。

SELECT *
FROM
    tbl_story t0_ 
      LEFT JOIN tbl_user t1_ ON t0_.creator_id = t1_.id 
      LEFT JOIN tbl_image t2_  ON t1_.avatar_id = t2_.id 
      LEFT JOIN tbl_image t3_  ON t0_.id = t3_.story_id 
      LEFT JOIN tbl_like t4_ ON t0_.id = t4_.story_id AND (t4_.creator_id = 3) 
      LEFT JOIN tbl_comment t5_ ON t0_.id = t5_.story_id 
      LEFT JOIN tbl_like t6_  ON t5_.id = t6_.comment_id AND (t6_.creator_id = 3) 
      LEFT JOIN tbl_user t7_  ON t5_.creator_id = t7_.id 
      LEFT JOIN tbl_image t8_ ON t7_.avatar_id = t8_.id 
      LEFT JOIN tbl_location_city t9_  ON t0_.city_id = t9_.id 
      LEFT JOIN tbl_location_state t10_ ON t9_.state_id = t10_.id 
      LEFT JOIN tbl_location_country t11_ ON t10_.country_id = t11_.id 
      LEFT JOIN tbl_story t12_ ON t0_.parent_id = t12_.id 
      LEFT JOIN tbl_page t13_ ON t0_.page_id = t13_.id 
      LEFT JOIN tbl_page_type t14_ ON t13_.page_type_id = t14_.id 
      LEFT JOIN tbl_story_tag t25_  ON t0_.id = t25_.story_id 
      LEFT JOIN tbl_tag t15_ ON t15_.id = t25_.tag_id 
      LEFT JOIN tbl_story_linked_user_reference t16_ ON t0_.id = t16_.story_id 
      LEFT JOIN tbl_user t17_ ON t16_.user_id = t17_.id 
      LEFT JOIN tbl_image t18_ ON t17_.avatar_id = t18_.id 
      LEFT JOIN tbl_story t19_  ON t0_.id = t19_.parent_id 
      LEFT JOIN tbl_album t20_ ON t0_.parent_album_id = t20_.id 
      LEFT JOIN tbl_image t21_ ON t20_.id = t21_.album_id 
      LEFT JOIN tbl_image_linked_user t22_ ON t21_.id = t22_.image_id 
      LEFT JOIN tbl_user t23_ ON t22_.user_id = t23_.id 
      LEFT JOIN tbl_image t24_ ON t23_.avatar_id = t24_.id 
WHERE t0_.creator_id = 3 
  AND t0_.is_draft = 0 
  AND t0_.type IN (0, 3, 2, 21) 
UNION
SELECT *
FROM
    tbl_story t0_ 
      LEFT JOIN tbl_user t1_ ON t0_.creator_id = t1_.id 
      LEFT JOIN tbl_image t2_  ON t1_.avatar_id = t2_.id 
      LEFT JOIN tbl_image t3_  ON t0_.id = t3_.story_id 
      LEFT JOIN tbl_like t4_ ON t0_.id = t4_.story_id AND (t4_.creator_id = 3) 
      LEFT JOIN tbl_comment t5_ ON t0_.id = t5_.story_id 
      LEFT JOIN tbl_like t6_  ON t5_.id = t6_.comment_id AND (t6_.creator_id = 3) 
      LEFT JOIN tbl_user t7_  ON t5_.creator_id = t7_.id 
      LEFT JOIN tbl_image t8_ ON t7_.avatar_id = t8_.id 
      LEFT JOIN tbl_location_city t9_  ON t0_.city_id = t9_.id 
      LEFT JOIN tbl_location_state t10_ ON t9_.state_id = t10_.id 
      LEFT JOIN tbl_location_country t11_ ON t10_.country_id = t11_.id 
      LEFT JOIN tbl_story t12_ ON t0_.parent_id = t12_.id 
      LEFT JOIN tbl_page t13_ ON t0_.page_id = t13_.id 
      LEFT JOIN tbl_page_type t14_ ON t13_.page_type_id = t14_.id 
      LEFT JOIN tbl_story_tag t25_  ON t0_.id = t25_.story_id 
      LEFT JOIN tbl_tag t15_ ON t15_.id = t25_.tag_id 
      LEFT JOIN tbl_story_linked_user_reference t16_ ON t0_.id = t16_.story_id 
      LEFT JOIN tbl_user t17_ ON t16_.user_id = t17_.id 
      LEFT JOIN tbl_image t18_ ON t17_.avatar_id = t18_.id 
      LEFT JOIN tbl_story t19_  ON t0_.id = t19_.parent_id 
      LEFT JOIN tbl_album t20_ ON t0_.parent_album_id = t20_.id 
      LEFT JOIN tbl_image t21_ ON t20_.id = t21_.album_id 
      LEFT JOIN tbl_image_linked_user t22_ ON t21_.id = t22_.image_id 
      LEFT JOIN tbl_user t23_ ON t22_.user_id = t23_.id 
      LEFT JOIN tbl_image t24_ ON t23_.avatar_id = t24_.id 
WHERE t0_.id IN 
        (SELECT 
          t26_.id 
        FROM tbl_story t26_ 
          INNER JOIN tbl_story_circle_visibility t28_ ON t26_.id = t28_.story_id 
          INNER JOIN tbl_circle t27_ ON t27_.id = t28_.circle_id 
          INNER JOIN tbl_user_circle_reference t29_ ON t27_.id = t29_.circle_id 
            AND (t29_.user_id = 3))
  AND t0_.is_draft = 0 
  AND t0_.type IN (0, 3, 2, 21) 
UNION
SELECT *
FROM
    tbl_story t0_ 
      LEFT JOIN tbl_user t1_ ON t0_.creator_id = t1_.id 
      LEFT JOIN tbl_image t2_  ON t1_.avatar_id = t2_.id 
      LEFT JOIN tbl_image t3_  ON t0_.id = t3_.story_id 
      LEFT JOIN tbl_like t4_ ON t0_.id = t4_.story_id AND (t4_.creator_id = 3) 
      LEFT JOIN tbl_comment t5_ ON t0_.id = t5_.story_id 
      LEFT JOIN tbl_like t6_  ON t5_.id = t6_.comment_id AND (t6_.creator_id = 3) 
      LEFT JOIN tbl_user t7_  ON t5_.creator_id = t7_.id 
      LEFT JOIN tbl_image t8_ ON t7_.avatar_id = t8_.id 
      LEFT JOIN tbl_location_city t9_  ON t0_.city_id = t9_.id 
      LEFT JOIN tbl_location_state t10_ ON t9_.state_id = t10_.id 
      LEFT JOIN tbl_location_country t11_ ON t10_.country_id = t11_.id 
      LEFT JOIN tbl_story t12_ ON t0_.parent_id = t12_.id 
      LEFT JOIN tbl_page t13_ ON t0_.page_id = t13_.id 
      LEFT JOIN tbl_page_type t14_ ON t13_.page_type_id = t14_.id 
      LEFT JOIN tbl_story_tag t25_  ON t0_.id = t25_.story_id 
      LEFT JOIN tbl_tag t15_ ON t15_.id = t25_.tag_id 
      LEFT JOIN tbl_story_linked_user_reference t16_ ON t0_.id = t16_.story_id 
      LEFT JOIN tbl_user t17_ ON t16_.user_id = t17_.id 
      LEFT JOIN tbl_image t18_ ON t17_.avatar_id = t18_.id 
      LEFT JOIN tbl_story t19_  ON t0_.id = t19_.parent_id 
      LEFT JOIN tbl_album t20_ ON t0_.parent_album_id = t20_.id 
      LEFT JOIN tbl_image t21_ ON t20_.id = t21_.album_id 
      LEFT JOIN tbl_image_linked_user t22_ ON t21_.id = t22_.image_id 
      LEFT JOIN tbl_user t23_ ON t22_.user_id = t23_.id 
      LEFT JOIN tbl_image t24_ ON t23_.avatar_id = t24_.id 
WHERE t0_.is_public = 1
  AND t0_.is_draft = 0 
  AND t0_.type IN (0, 3, 2, 21) 
ORDER BY t0_.created_at DESC
LIMIT 7

对于具有大量连接的查询，运行顺序较慢

1 个答案: