I have a native query that does a batch insert into a MySQL database:

    String sql = "insert into t1 (a, b) select x, y from t2 where x = 'foo'";
    EntityTransaction tx = entityManager.getTransaction();
    try {
        tx.begin();
        int rowCount = entityManager.createNativeQuery(sql).executeUpdate();
        tx.commit();
        return rowCount;
    }
    catch(Exception ex) {
        tx.rollback();
        log.error(...);
    }

This query causes a deadlock: while it reads from t2 with insert .. select, another process tries to insert a row into t2.

I don't care about the consistency of reads from t2 when doing an insert .. select and want to set the transaction isolation level to READ_UNCOMMITTED.

How do I go about setting it in JPA?