Lucene.Net is not giving any results but Luke does - lucene

Question

I have created a Lucene Index using StandardAnalyzer with following three fields.
StreetName
City
State
I am using below wrapper class to ease out writing boolean queries
public interface IQuery
{
BooleanQuery GetQuery();
}
public class QueryParam : IQuery
{
public string[] Fields { get; set; }
public string Term { get; set; }
private BooleanQuery _indexerQuery;
public QueryParam(string term, params string[] fields)
{
Term = term;
Fields = fields;
}
public BooleanQuery GetQuery()
{
_indexerQuery = new BooleanQuery();
foreach (var field in Fields)
_indexerQuery.Add(new FuzzyQuery(new Term(field, Term)), Occur.SHOULD);
return _indexerQuery;
}
}
public class AndQuery : IQuery
{
private readonly IList<IQuery> _queryParams = new List<IQuery>();
private BooleanQuery _indexerQuery;
public AndQuery(params IQuery[] queryParams)
{
foreach (var queryParam in queryParams)
{
_queryParams.Add(queryParam);
}
}
public BooleanQuery GetQuery()
{
_indexerQuery = new BooleanQuery();
foreach (var query in _queryParams)
_indexerQuery.Add(query.GetQuery(), Occur.MUST);
return _indexerQuery;
}
}
public class OrQuery : IQuery
{
private readonly IList<IQuery> _queryParams = new List<IQuery>();
private readonly BooleanQuery _indexerQuery = new BooleanQuery();
public OrQuery(params IQuery[] queryParams)
{
foreach (var queryParam in queryParams)
{
_queryParams.Add(queryParam);
}
}
public BooleanQuery GetQuery()
{
foreach (var query in _queryParams)
_indexerQuery.Add(query.GetQuery(), Occur.SHOULD);
return _indexerQuery;
}
public OrQuery AddQuery(IQuery query)
{
_queryParams.Add(query);
return this;
}
}
Below query is not giving me any results in Lucene.Net but when i search the same query in Luke,it works flawlessly.
var query = new AndQuery(new QueryParam(city.ToLower(), "city"), new QueryParam(state.ToLower(), "state"), new QueryParam(streetAddress.ToLower(), "streetname"));
Executing query.GetQuery() gives me below resultant query.
{+(city:tampa~0.5) +(state:fl~0.5) +(street:tennis court~0.5)}

Answer 1

You can search using BooleanQuery. Break your term with white space in segments, then create the query and search in index.
EX:-
BooleanQuery booleanQuery = new BooleanQuery()
BooleanQuery searchTermQuery = new BooleanQuery();
foreach (var searchTerm in searchTerms)
{
var searchTermSegments = searchTerm.Split(new[] { " " }, StringSplitOptions.RemoveEmptyEntries);
if (searchTermSegments.Count() > 1)
{
searchTermQuery.Clauses().Clear();
foreach (var SegTex in searchTermSegments)
{
searchTermQuery.Add( new FuzzyQuery(new Term("FieldName", SegTex.ToLower().Trim())),BooleanClause.Occur.MUST);
}
booleanQuery.Add(searchTermQuery, BooleanClause.Occur.MUST);
}
else
{
booleanQuery.Add(new FuzzyQuery(new Term("FieldName", searchTerm.ToLower().Trim())), BooleanClause.Occur.MUST);
}
}

Answer 2

The problem is the treatment of tennis court. You haven't shown how you are indexing these fields, but I will assume they are tokenized in the index, using something like a StandardAnalyzer, for instance. This means, "tennis court" will be split into two separate terms "tennis" and "court". When creating a FuzzyQuery manually, though, there is no analysis or tokenization, and so you will only have a single term "tennis court". There is a large edit distance between "tennis court" and either "tennis" (6 edits) or "court" (7 edits), so neither of them match.
A source of confusion here seems to be that
+(city:tampa~0.5) +(state:fl~0.5) +(street:tennis court~0.5)
Seems to work. It is not safe, however, to assume that the text query output for debugging can be run through the queryparser to generate the same query, and this is a good example. The QueryParser syntax is simply not capable of expressing everything you can do with manually constructed queries. Running that query through the query parser will generate a query more like:
+(city:tampa~0.5) +(state:fl~0.5) +((street:tennis) (defaultField:court~0.5))
Which will find a match, since we can expect it to find city:tampa, state:fl, and street:tennis (See this Lucene Query Parser documentation section for another example explaining this behavior of the query parser). Whether it finds a match on court in the default field I have no idea, but it doesn't really need to.
A PhraseQuery is the typical way to string multiple terms (words) together in a Lucene Query (this would look like street:"tennis court" in a parsed query).