Thanks Adrien.
I've scraped together a simple program in the Lucene 4.2 idiom (see below).
Does this illustrate what you meant by your last sentence?
The code adds/indexes 5 documents all of whose content is identical, but
whose 'id' field is unique ("v1" through "v5"). It then queries the 'id'
field for the pattern "v*".
While we're at it, what method should I be using to obtain merely the
original document itself after a query? My println of "Document=" +
doc.toString() shows this:
Document=Document<stored,indexed,tokenized,omitNorms,indexOptions=DOCS_ONLY<id:v2>
stored,indexed,tokenized<content:This is a test; for the next 60
seconds...>>
But if I'm interested in just obtaining the "content" field ("This is a
test; for the next..."), what should I do?
-Paul
public class TestLucene
{
public static int id = 0;
public static void main(String[] args)
{
RAMDirectory idx = new RAMDirectory();
try
{
IndexWriterConfig conf = new
IndexWriterConfig(Version.LUCENE_42, new
StandardAnalyzer(Version.LUCENE_42));
IndexWriter writer = new IndexWriter(idx, conf);
for ( int n=0; n < 5; n++ )
{
writer.addDocument(createDocument("This is a test; for the
next 60 seconds..."));
}
writer.close();
IndexReader reader = DirectoryReader.open(idx);
IndexSearcher searcher = new IndexSearcher(reader);
Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_42);
QueryParser parser = new QueryParser(Version.LUCENE_42, "id",
analyzer); // searching on the id field
Query query =
parser.parse("v*");
// look for "v*" within the id field
TopDocs hits = searcher.search(query, null, 100);
for ( ScoreDoc scoreDoc : hits.scoreDocs )
{
Document doc = searcher.doc(scoreDoc.doc);
String idField = doc.get("id");
System.out.println("ID=" + idField);
System.out.println("Document=" + doc.toString());
}
System.out.println("Total hits=" + hits.totalHits);
}
catch(Exception e)
{
System.out.println("CAUGHT EXCEPTION=" +
e.getLocalizedMessage());
}
}
private static Document createDocument(String content)
{
Document doc = new Document();
id++;
StringField strField = new StringField("id", "v" + id,
Field.Store.YES); // give the document a unique identifier
doc.add(strField);
TextField txtField = new TextField("content", content,
Field.Store.YES);
doc.add(txtField);
return doc;
}
}
On Wed, Mar 27, 2013 at 11:37 AM, Adrien Grand <jpou...@gmail.com> wrote:
> Hi Paul,
>
> On Wed, Mar 27, 2013 at 1:58 PM, Paul Bell <arach...@gmail.com> wrote:
> > As to the ideas raised in the links you pointed me to: the first link
> shows
> > the instantiation of a Term object via
> >
> > writer.UpdateDocument(new Term("IDField", *id*), doc);
> >
> > yet in the 4.2.0 docs I see no Term constructor that allows this "id"
> > field.
>
> I think this is this one:
>
> http://lucene.apache.org/core/4_2_0/core/org/apache/lucene/index/Term.html#Term(java.lang.String
> ,
> java.lang.String)
>
> > But this raises an interesting question: is it possible to tell Lucene
> that
> > the Document I've given it to index has a specific identifier? Here's an
> > example of what I mean. Suppose that the DB in question is a NoSQL type
> of
> > the graph flavor. I add a vertex to that graph. The vertex contains some
> > properties, e.g., name and type, whose values are text strings. I want
> > Lucene to index these data AND I want to know some kind of identifier for
> > that vertex Document. I would prefer to give Lucene that ID, though I
> might
> > be able to tolerate it giving it to me.
>
> Lucene has no schema that would allow you to specify a primary key,
> but there is the IndexWriter.updateDocument method that allows for
> atomic updates of documents:
>
> http://lucene.apache.org/core/4_2_0/core/org/apache/lucene/index/IndexWriter.html#updateDocument(org.apache.lucene.index.Term
> ,
> java.lang.Iterable)
>
> You just need to pass a term where the field name is the name of your
> primary key field and the value is the actual ID.
>
> --
> Adrien
>
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