Thanks for the reference. This is indeed an interesting piece of documentation, but as far as I understand it, we should be able to increase the value to 65,535 - 3, because the LHS of the IN predicate is a path that can be composed of 3 identifiers (catalog, table, column).

Also, it’s nice that you changed the limit in the PR, but I’d like to see a test that creates a list of size LIMIT * 2 to see that this actually works.

I think a simple test that just runs something like the following should be enough:

entityManager.createQuery( "select p from Person p where p.id in :ids" )
      .setParameter( "ids", IntStream.range( 0, MAX_COUNT * 2 ).boxed().collect( Collectors.toList() ) )
      .getResultList()
);

You can take inspiration for this from e.g. org.hibernate.orm.test.query.MaxInExpressionParameterPaddingTest