So here’s a very interesting one that came up here: https://stackoverflow.com/questions/76073151/incorrect-sql-where-clause-generated-from-hql-since-hibernate-6-using-test-on-le

Please ignore the actual query that the user displays, as you can see in my answer, it’s not a reasonable query to write.

Instead just focus on the change in behavior.

Given the query:

SELECT book
FROM Book book
   LEFT JOIN book.author a
WHERE a is not null

We optimize this to the SQL:

select
    b1_0.id,
    b1_0.author_id,
    b1_0.publishingHouse_id,
    b1_0.title 
from
    Book b1_0 
where
    b1_0.author_id is not null

which is frankly pretty awesome.

But now consider this variation:

SELECT book 
FROM Book book 
   LEFT JOIN book.author a WITH a.alive = true 
WHERE a is not null

Now the generated SQL is:

select
    b1_0.id,
    b1_0.author_id,
    b1_0.publishingHouse_id,
    b1_0.title 
from
    Book b1_0 
left join
    Author a1_0 
        on a1_0.id=b1_0.author_id 
        and a1_0.alive=true 
where
    b1_0.author_id is not null

and, after reflection, I’m inclined to agree with the user that this is not quite correct.

I think they’re probably right to say that a is not null should translate to {{a1_0.id is not null}}in this particular case.