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From Yonik Seeley <ysee...@gmail.com>
Subject Re: need some advice/help with negative query.
Date Fri, 06 Jan 2006 19:57:39 GMT
Should we should detect the case of all negative clauses and throw in
a MatchAllDocsQuery?

I guess this would be done in the QueryParser, but one could also make
a case for doing it in the BooleanQuery.

-Yonik

On 1/6/06, Erik Hatcher <erik@ehatchersolutions.com> wrote:
> With Lucene's trunk, there is a MatchAllDocsQuery.   You could use
> this in a BooleanQuery with your negative-only query.
>
> Another option, if you're at Lucene 1.4.3 is to index the same value
> for a dummy field for every document (say like "dummy:all") and use a
> TermQuery in a BooleanQuery with the negative-only query.
>
> As for BitSet's, if you need to go that route a QueryFilter would
> give you the BitSet back that you could easily complement, but that
> might be a bit overkill for what you need given the option above.
>
>         Erik
>
>
> On Jan 6, 2006, at 12:04 PM, Beady Geraghty wrote:
>
> > I would like to do queries that are negative. I mean a query with
> > only negative terms and phrases.  For example, retrieve all
> > documents that do not contain the term "apple".
> >
> > For now, I have a limited set of documents (say, 10000) to index.
> > I can create a bitset that represents the search result of hits on
> > "apple".
> > Then I complement (XOR) the result.
> > Each bit corresponds to a document ID.
> > My question is :
> > Inside Lucene, are the hits represented in some form of a bitset.
> > Can I get at it directly.   I saw the BitSet class.  (I now use
> > Java's Bitset class).
> > Assuming that hits are internally represented as bitset, for a
> > small number of documets, the bitset won't be very big,
> > and if there are plenty of hits and many many more documents,
> > is the bitset still  kept entirely
> > in memory as well ?
> >
> > Thank you
>
>
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