Spring Data JPA + openjpa: Is it possible to join a table not in OR-Hierarchy?

Question

So, the following usecase:

I've got two tables and the corresponding entities, lets call them table A (the left) and table B (the right). Both tables have a column "size", but at my OR-Model, table a has no reference to an object of table b. Now what I want to achieve (via Spring Data JPA @Query-Annotation / JPQL, not using native SQL) is something like the following (a little simplified) Query:

@Query("select a from TheLeftTable a join TheRightTable b" +
       "where b.size = a.size ")
Page<TheLeftTable> findAllAvailableEntries(Pageable p);

but i get the following exception cause when trying to start my tomcat:

...Caused by: org.apache.openjpa.persistence.ArgumentException: Encountered "join TheRightTable b" at character 48, but expected: [".", "FETCH", "INNER", "JOIN", "LEFT", ]

So my Question is: Is this generally possible or not to create such a query with JPQL / JPA only? Please remember: In My OR-Model, TableA has no Object from Table B. My simplified Entitiy-Properties are looking just like this:

@Column(name = "size")
String size;

If it is not possible, any other ideas would be great. (Except changing my Entity for Table A to have the object of Entity B, which is sadly not possible)

Answer 1

No problem, it is possible to do that:

SELECT a FROM TheLeftTable a, TheRightTable b WHERE b.size = a.size

It is called cross join, but if the columns size are indexed, you won't notice it any performance issues.