private int IndexingText(int documentId, string text, string fieldName)
        {
            var numberOfTokens = 0;
            var tokens         = _tokinizer.GetTokens(text);
            var invertedIndex  = _fieldIndex.GetIndexer(fieldName);

            foreach (var token in tokens)
            {
                var wordId   = _vocabulary.GetOrAddIndex(token.Term.ToLower());
                var termInfo = new TermInformation()
                {
                    TermIndex = token.Index, StartIndex = 0, StopIndex = 0
                };
                invertedIndex.Insert(wordId, documentId, termInfo);
                numberOfTokens++;
            }
            return(numberOfTokens);
        }