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From Milind <mili...@gmail.com>
Subject Re: Why does this search fail?
Date Wed, 27 Aug 2014 13:54:18 GMT
I see.  This is going to be extremely difficult to explain to end users.
It doesn't work as they would expect.  Some of the tokenizing rules are
already somewhat confusing.  Their expectation is that it should work the
way their searches work in Google.

It's difficult enough to recognize that because the period is surrounded by
a digit and alphabet (as opposed to 2 digits or 2 alphabets), it gets
tokenized.  So I'd have expected that C0001.DevNm00* would effectively
become a search for C0001 OR DevNm00*.  But now, because of the presence of
the wildcard, it's considered as 1 term and the period is not a tokenizer.
That's actually good, but now the fact that it's still considered as 2
terms for wildcard searches makes it very unintuitive.  I don't suppose
that I can do anything about making wildcard search use multiple terms if
joined together with a tokenizer.  But is there any way that I can force it
to go through an analyzer prior to doing the search?




On Tue, Aug 26, 2014 at 4:21 PM, Jack Krupansky <jack@basetechnology.com>
wrote:

> Sorry, but you can only use a wildcard on a single term. "C0001.DevNm001"
> gets indexed as two terms, "c0001" and "devnm001", so your wildcard won't
> match any term (at least in this case.)
>
> Also, if your query term includes a wildcard, it will not be fully
> analyzed. Some filters such as lower case are defined as "multi-term", so
> they will be performed, but the standard tokenizer is not being called, so
> the dot remains and this whole term is treated as one term, unlike the
> index analysis.
>
> -- Jack Krupansky
>
> -----Original Message----- From: Milind
> Sent: Tuesday, August 26, 2014 12:24 PM
> To: java-user@lucene.apache.org
> Subject: Why does this search fail?
>
>
> I have a field with the value C0001.DevNm001.  If I search for
>
>    C0001.DevNm001 --> Get Hit
>    DevNm00*       --> Get Hit
>    C0001.DevNm00*  --> Get No Hit
>
> The field gets tokenized on the period since it's surrounded by a letter
> and and a number.  The query gets evaluated as a prefix query.  I'd have
> thought that this should have found the document.  Any clues on why this
> doesn't work?
>
> The full code is below.
>
>        Directory theDirectory = new RAMDirectory();
>        Version theVersion = Version.LUCENE_47;
>        Analyzer theAnalyzer = new StandardAnalyzer(theVersion);
>        IndexWriterConfig theConfig =
>                            new IndexWriterConfig(theVersion, theAnalyzer);
>        IndexWriter theWriter = new IndexWriter(theDirectory, theConfig);
>
>        String theFieldName = "Name";
>        String theFieldValue = "C0001.DevNm001";
>          Document theDocument = new Document();
>          theDocument.add(new TextField(theFieldName, theFieldValue,
> Field.Store.YES));
>          theWriter.addDocument(theDocument);
>        theWriter.close();
>
>        String theQueryStr = theFieldName + ":C0001.DevNm00*";
>        Query theQuery =
>            new QueryParser(theVersion, theFieldName,
> theAnalyzer).parse(theQueryStr);
>        System.out.println(theQuery.getClass() + ", " + theQuery);
>        IndexReader theIndexReader = DirectoryReader.open(theDirectory);
>        IndexSearcher theSearcher = new IndexSearcher(theIndexReader);
>        TopScoreDocCollector collector = TopScoreDocCollector.create(10,
> true);
>        theSearcher.search(theQuery, collector);
>        ScoreDoc[] theHits = collector.topDocs().scoreDocs;
>        System.out.println("Hits found: " + theHits.length);
>
> Output:
>
> class org.apache.lucene.search.PrefixQuery, Name:c0001.devnm00*
> Hits found: 0
>
>
> --
> Regards
> Milind
>
> ---------------------------------------------------------------------
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>
>


-- 
Regards
Milind

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