LuceneQueryModifier

Class Overview

This class will clone the org.apache.lucene.search.Query and add a org.apache.lucene.search.MatchAllDocsQuery to the portion of the query that require them. This inspects the query to determine if there are any nodes in the query that are marked as MUST_NOT AND they do not have a positive query to work against. This is because Lucene will drop queries of this kind instead of trying to find the correct result. When we specify a query that is -A || B lucene treats this as equivilent to B. When we specify this query what we mean is (-A && ALL_VALUES) || B which is obviously not equivilent to B. The algorithm for determining if a org.apache.lucene.search.BooleanQuery should have a org.apache.lucene.search.MatchAllDocsQuery added to it with an occur of MUST_NOT is: Case 1: BooleanQuery contains only MUST_NOT clauses THEN add a org.apache.lucene.search.MatchAllDocsQuery Case 2: BooleanQuery contains at least one MUST and no SHOULD THEN do not add a org.apache.lucene.search.MatchAllDocsQuery Case 3: BooleanQuery contains at least one SHOULD THEN add a org.apache.lucene.search.MatchAllDocsQuery to each MUST_NOT portion of the query. This may mean that we need to rewrite the a single term to be a BooleanQuery that contains the single term AND the org.apache.lucene.search.MatchAllDocsQuery. NOTE: A BooleanQuery that contains at least one MUST and at least one SHOULD is the same as Case 2 since the MUST portion of the query will provide a positive set of results.

Summary