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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: [Lucene] Frequencies and positions - are they stored per field?
Date Tue, 04 Oct 2011 09:53:01 GMT
Lucene always uses a field, a query using a term without a field is
impossible. See each field as a parallel inverted index; all statistics are
per field, too. If you pass a query without a field name to QueryParser it
will chose the default field, that’s given when creating the QueryParser.

Uwe

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de


> -----Original Message-----
> From: sol myr [mailto:solmyr72@yahoo.com]
> Sent: Tuesday, October 04, 2011 11:46 AM
> To: lucene
> Subject: [Lucene] Frequencies and positions - are they stored per field?
> 
> 
> 
> Hi,
> 
> I use Lucene, but an not familiar with its internals.
> I'd appreciate help understanding whether Term Frequences and Positions -
are
> stored  per Document of per Field?
> On the one hand, I never ask for "Field.TermVector" because I read it's
only
> required for "MoreLikeThis" (which I don't need).
> On the other hand, my searches *are* based on fields...
> 
> Here's my code:
> // Write (without Field.TermVector):
> 
> Document doc=new Document();
> doc.add(new Field("subject",  "Requisition request", Store.YES,
> Index.ANALYZED)); doc.add(new Field("body",  "Attached is an Urgent
> requisition request", Store.YES, Index.ANALYZED)); write.addDocument(doc);
> 
> // And my Query:
> Query query=parser.parse("subject : urgent");
> 
> Now how does Lucene manage this query?
> I asked it to search the "subject" Field.
> But if the "inverted index" doesn't keep fields, it would only remember
that
> "The term 'Urgent' appears in SOME FIELD of document#1 "...
> Isn't it true?
> 
> If so, how would it make sure to retrieve only documents that match in the
> Subject ?
> 
> Thanks.
> 
> 
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