Here is an excerpt from the documentation <http://docs.jboss.org/hibernate/search/5.0/reference/en-US/html_single/#search-query-querydsl>

> This first example takes a Coffee id and finds the matching coffees across all fields. To be fair, this is not all fields:
> 
> - the id is excluded as it would not make much sense
> - fields storing term vectors are considered
> - fields storing the actual value are considered
> - numeric fields are excluded today but that might change in a future version

More Like This fundamentally looks at similar terms text wise and try to find other documents that have the same terms. If you include text (or later numeric) ids, you add a term that restrict things to one entity and not a similar set of entities. That's the effect I'm trying to avoid basically.