Fail-fast predicate

Hibernate Search
1

Is it a predicate which guarantees no search results without performing any search?

My use case is: building a query from a complex code hierarchy where I can’y guarantee more predicates won’t be added, but I hit a condition for which the search should return none.

In case there is not, what could be the less expensive no-result predicate?

I am currently using a must for a negative id, but I fear that is a costly way to make my search return nothing.

Thanks

2

This looks like a reasonable use case; I opened [HSEARCH-4489] - Hibernate JIRA to add a matchNone predicate to Hibernate Search.

In the meantime, you can use this code:

List<MyEntity> hits = searchSession.search( MyEntity.class )
        .where( f -> f.bool( b -> { 
            if ( <the query must not match anything> ) {
                b.mustNot( f.matchAll() );
            }
            else { 
                b.must( ... ); // Add regular predicates
            }
        } ) )
        .fetchHits( 20 );

As you can see here, Lucene will optimize this and turn the boolean predicate into a predicate that matches no documents, which is what you want. Elasticsearch uses Lucene under the hood, so it should behave similarly.

3

Awesome! Thank you @yrodiere