我有一个articles500k行的表.一篇文章有一份作者列表.我正在尝试创建一个查询,以获取最新发布的作者列表文章.
我使用了以下HQL查询,它可以获得我想要的但运行速度很慢(~4s)
select author, article
from Article article inner join article.authors author
where (author.id, article.publishedAt) in
(select author.id, max(article.publishedAt)
from Article article join article.authors author
where author.id in (authors_list))
group by author.id
Run Code Online (Sandbox Code Playgroud)
在普通的SQL中可能更好的查询是:
select * from (
select articles.id, author.id
from articles, article_authors, authors
where articles.id = article_authors.article_id and
article_authors.author_id=authors.id
and author.id in (author_list)
order by articles.publishedAt desc
) b
group by authors.id;
Run Code Online (Sandbox Code Playgroud)
但是从Hibernate文档中可以看出,HQL子查询只能出现在select或where子句中. http://docs.jboss.org/hibernate/orm/3.3/reference/en/html/queryhql.html#queryhql-subqueries
有没有办法使用HQL或其他方式来模拟这种查询来增强查询的性能?