Lucene fuzzy search on a phrase (FuzzyQuery + SpanQuery)
I am looking for a way of coding the lucene fuzzy query that searches all the documents, which are relevant to an exact phrase. If I search "mosa employee appreciata", a document contains "most employees appreciate" will be returned as the result.
I tried to use:
FuzzyQeury = new FuzzyQuery(new Term("contents","mosa employee appreicata"))
Unfortunately, it empirically doesn't work. The FuzzyQuery employs the editor distance, theoretically, "mosa employee appreciata" should be matched with "most employees appreciate" provide the appropriate distance is given. It seems a bit odd.
Any clues? Thank you.
Answer
There are two likely problems here. First: I'm guessing the "contents" field is being analyzed such that "most employees apreciate" is not a term, but rather three terms. Defining as a single term is not appropriate in this case.
However, even if the content listed is a single term, a second likely problem we have is that there is too much distance between the terms to get a match. The Damerau-Levenshtein distance between mosa employee appreicata and most employees appreciate is 4 (the approximate distance, incidentally, between my average first shot at spelling
"Damerau-Levenshtein" and the correct spelling). Fuzzy Query, as of 4.0, handles edit distances of no more than 2, due to performance constraints, and the assumption that larger distances are usually not particularly relevant.
If you need to perform a phrase query with fuzzy terms, you should look into either MultiPhraseQuery, or combine a set of SpanQueries (especially SpanMultiTermQueryWrapper and SpanNearQuery) to meet your needs.
SpanQuery[] clauses = new SpanQuery[3];
clauses[0] = new SpanMultiTermQueryWrapper(new FuzzyQuery(new Term("contents", "mosa")));
clauses[1] = new SpanMultiTermQueryWrapper(new FuzzyQuery(new Term("contents", "employee")));
clauses[2] = new SpanMultiTermQueryWrapper(new FuzzyQuery(new Term("contents", "appreicata")));
SpanNearQuery query = new SpanNearQuery(clauses, 0, true)
And since none of the individual terms have an edit distance greater than 2, this should be more effective.