How can QueryParser from Apache Lucene be used to have a query that either contains term A or term B (or both, but at least one of them). EDIT: Also, it contains other MUST clauses, e.g., it must contain C and it must contain either A or B.
Is this then correct?
+(A OR B) +C
It is simply: A OR B (or just A B)
This will generate two BooleanClauses with Occur.SHOULD. In this case, at least one clause has to match for the whole BooleanQuery to match:
/** Use this operator for clauses that <i>should</i> appear in the
* matching documents. For a BooleanQuery with no <code>MUST</code>
* clauses one or more <code>SHOULD</code> clauses must match a document
* for the BooleanQuery to match.
* @see BooleanQuery#setMinimumNumberShouldMatch
*/
SHOULD { @Override public String toString() { return ""; } },
Answer to the updated question:
(A OR B) AND C should do what you want.
I'm not really sure about +(A OR B) +C since it looks like it should work but you stated that +(A OR B) doesn't work like you expect it to in your original question.
To make sure, you can take a look at what QueryParser generates. You'd need this kind of query structure:
BooleanQuery
BooleanQuery
TermQuery: ATermQuery: BTermQuery: C