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From "Luke Shannon" <lshan...@futurebrand.com>
Subject Re: Negative Match
Date Fri, 11 Feb 2005 14:52:34 GMT
Hey Erik;

The problem with that approach is I get document that don't have a
kcfileupload field. This makes sense because these documents don't match the
prohibited
clause, but doesn't fit with the requirements of the system.

What I like best about this approach is it doesn't require a filter. The
system I integrate with is presently designed to accept a query object. I
wasn't looking forward to having to add the possibility that queries might
require filters. I may have to still do this, but for now I would like to
try this and see how it goes.

Thanks,

Luke

----- Original Message ----- 
From: "Erik Hatcher" <erik@ehatchersolutions.com>
To: "Lucene Users List" <lucene-user@jakarta.apache.org>
Sent: Thursday, February 10, 2005 7:23 PM
Subject: Re: Negative Match


>
> On Feb 10, 2005, at 4:06 PM, Luke Shannon wrote:
>
> > I think I found a pretty good way to do a negative match.
> >
> > In this query I am looking for all the Documents that have a
> > kcfileupload
> > field with any value except for jpg.
> >
> >         Query negativeMatch = new WildcardQuery(new
> > Term("kcfileupload",
> > "*jpg*"));
> >          BooleanQuery typeNegAll = new BooleanQuery();
> >         Query allResults = new WildcardQuery(new Term("kcfileupload",
> > "*"));
> >         IndexSearcher searcher = new IndexSearcher(fsDir);
> >         BooleanClause clause = new BooleanClause(negativeMatch, false,
> > true);
> >         typeNegAll.add(allResults, true, false);
> >         typeNegAll.add(clause);
> >         Hits hits = searcher.search(typeNegAll);
> >
> > With the little testing I have done this *seems* to work. Does anyone
> > see a
> > problem with this approach?
>
> Sure.... do you realize what WildcardQuery does under the covers?  It
> literally expands to a BooleanQuery for all terms that match the
> pattern.  There is an adjustable limit built-in of 1,024 clauses to
> BooleanQuery.  You obviously have not hit that limit ... yet!
>
> You're better off using the advice offered on this thread
> previously.... create a single dummy field with a fixed value for all
> documents.  Combine a TermQuery for that dummy value with a prohibited
> clause like y our negativeMatch above.
>
> Erik
>
>
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