SQL优化：提高查询效率的技巧

优化后的SQL如下：

SELECT post.id,
       post.vote_id,
       post.title,
       post.user_id,
       post.user_nickname,
       post.ctime,
       post_text.content,
       post.ptime,
       post.ptime_ms,
       post.view_count,
       post.status,
       post.like_count,
       post.forward_count,
       post.comment_count,
       post.type,
       post.origin_type,
       post.origin_post_id,
       post.last_post_id,
       post.favorite_count,
       post.post_source,
       post.fund_forum_id,
       post.weight_v2
FROM `post`
JOIN post_text ON post.id = post_text.post_id
LEFT JOIN community.post_file ON post.id = post_file.post_id AND post_file.type = 1 AND post_file.status = 0
WHERE post.status = 2
  AND post.id NOT IN (4682, 2844, 2669)
  AND (post.app_module = 0 OR (post.app_module = 1 AND post.recommended = 1))
  AND post_file.post_id IS NULL
GROUP BY post.id
ORDER BY post.weight_v2 DESC, post.ptime_ms DESC, post.id DESC
LIMIT 20;

SELECT post.id,
       post.vote_id,
       post.title,
       post.user_id,
       post.user_nickname,
       post.ctime,
       post_text.content,
       post.ptime,
       post.ptime_ms,
       post.view_count,
       post.status,
       post.like_count,
       post.forward_count,
       post.comment_count,
       post.type,
       post.origin_type,
       post.origin_post_id,
       post.last_post_id,
       post.favorite_count,
       post.post_source,
       post.fund_forum_id,
       post.weight_v2
FROM `post`
JOIN post_text ON post.id = post_text.post_id
INNER JOIN community.post_file ON post.id = post_file.post_id AND post_file.type = 1 AND post_file.status = 0
WHERE post.status = 2
  AND post.id NOT IN (4682, 2844, 2669)
  AND (post.app_module = 0 OR (post.app_module = 1 AND post.recommended = 1))
GROUP BY post.id
ORDER BY post.weight_v2 DESC, post.ptime_ms DESC, post.id DESC
LIMIT 10;

优化说明：

将左连接（LEFT JOIN）改为内连接（INNER JOIN），提高查询效率。
修改表连接顺序，先连接主表post，再连接关联表post_text和community.post_file，可以减小连接的数据规模，提高查询效率。
将子查询中的post_file.post_id IS NULL条件移至主查询的WHERE语句中，避免使用子查询，简化SQL语句。
对JOIN和WHERE条件进行逻辑判断时，使用括号将条件分组，提高查询语句的可读性。