Guillaume Smet not sure if you pinged me about this before or after we discussed it on Gitter. jpa pretty clearly states that subqueries are not supported in the select clause. It's really just a question of whether we want to support that as an extension (and if we do, at the least, this should be protected by JpaCompliance). I do not remember the exact discussion on the EG about why we decided to not support it in the select clause. Conceptually it's fine, some databases may not support it.