I have a very simple situation: Invoice has a collection of InvoiceItem(s).
I have to fetch invoice items only. The question is: what will work faster:

a) return em.createNamedQuery(InvoiceItem.FIND_BY_INVOICE_ID).
setParameter(1, invoiceId).
getResultList();

b) return em.find(Invoice.class, invoiceId).getInvoiceItems();