Lucene.NET Phrase search returning no results

Question

EDIT

Ok I worked it out. When I was adding the terms one at a time to the PhraseQuery object it was retaining the common words. In the case it was "The".

What I have done instead is used the QueryParser object to parse the query (including the quotation marks). This drops the common words and the phrase query now works like a charm.

List<string> searchList = Regex.Matches(searchTerms, @"(?<match>\w+)|\""(?<match>[\w\s]*)""")
                   .Cast<Match>()
                   .Select(m => m.Groups["match"].Value)
                   .ToList();

QueryParser parser = new QueryParser(LuceneFields.BODY, Analyzer);
BooleanQuery booleanQuery = new BooleanQuery();

// go through each term
foreach (string term in searchList)
{
  Query query = null;
  if (term.Contains(" ")) // multi word phrase
    query = parser.Parse("\"" + term + "\"");
  else
    query = parser.Parse(term);
  if (query.ToString() != "")
    booleanQuery.Add(query, BooleanClause.Occur.MUST);
}

I am creating a simple search using Lucene.NET and I am having a bit of trouble getting phrase searching to work properly as I am combining it with a boolean query.

The following code is being used to search:

List<string> searchList = Regex.Matches(searchTerms, @"(?<match>\w+)|\""(?<match>[\w\s]*)""")
                   .Cast<Match>()
                   .Select(m => m.Groups["match"].Value)
                   .ToList();

QueryParser parser = new QueryParser(LuceneFields.BODY, Analyzer);
BooleanQuery booleanQuery = new BooleanQuery();

// go through each term
foreach (string term in searchList)
{
  Query query = null;

  if (term.Contains(" ")) // multi word phrase
  {
    query = new PhraseQuery();
    foreach (string str in term.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries))
    {
      ((PhraseQuery)query).Add(new Term(LuceneFields.BODY, str));
    }
  }
  else
    query = parser.Parse(term);

  string strQuery = query.ToString();

  if (query.ToString() != "")
    booleanQuery.Add(query, BooleanClause.Occur.MUST);
}

I have checked the query that is being created and it looks OK to me:

+body:"The following table"

And I have also confirmed this text is actually in the Lucene index as you can see from a search result just searching for "table"

enter image description here

I'm at a loss really for what could be the problem.

I have used the following code to create the index:

Directory = FSDirectory.Open(new System.IO.DirectoryInfo(IndexDirectory));
Analyzer = new StandardAnalyzer(Version); 

using (IndexWriter indexWriter = new IndexWriter(Directory, Analyzer, new IndexWriter.MaxFieldLength(Int32.MaxValue)))
{
  Response.Write("Adding document...");
  Document document = new Document();

  // Store the IDDataContent
  document.Add(new Field(LuceneFields.ID, id.ToString(), Field.Store.YES, Field.Index.ANALYZED));

  // store the url to the file itself
  document.Add(new Field(LuceneFields.HREF, FileURL, Field.Store.YES, Field.Index.ANALYZED));

  //document.Add(new Field(LuceneFields.TITLE, Article.Title, Field.Store.YES, Field.Index.ANALYZED));

  // store the text of the PDF
  document.Add(new Field(LuceneFields.BODY, PdfContents, Field.Store.YES, Field.Index.ANALYZED));
  indexWriter.AddDocument(document);
  indexWriter.Optimize();
  indexWriter.Commit();
}

naresh naresh · Accepted Answer · 2012-05-07T09:40:29

Check if you are using same analyzer while indexing and search.
Check whether the terms you are searching for actually exist in index. (using luke)

Lucene.NET Phrase search returning no results

2 Answers