When running Hibernate Reactive’s ManyToManyTest , the test fails with:

java.util.concurrent.CompletionException: org.hibernate.HibernateException: java.util.concurrent.CompletionException: io.vertx.pgclient.PgException: ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list (42P10)

The problematic part is this which leads to the following generated SQL:

 select distinct a1_0.id, b1_0.Author_id, b1_1.id, b1_1.title, a1_0.name
from MTMAuthor a1_0
         left join (MTMAuthor_MTMBook b1_0 join MTMBook b1_1 on b1_1.id = b1_0.books_id) on a1_0.id = b1_0.Author_id
order by b1_0.books_id

The test worked just fine in Hibernate Reactive’s main branch (using ORM 5.5)

A discussion of the issue can also be found here.