On Feb 11, 2005, at 9:52 AM, Luke Shannon wrote:
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.
Ok, so instead of using the dummy field with a single dummy value, use a dummy field to list the field names. Field.Keyword("fields","kcfileupload"), but only for the documents that should have it, of course. Then use a query like (using QueryParser syntax, but do it with the API as you have since QueryParser doesn't support leading wildcards):
+fields:kcfileupload -kcfileupload:*jpg*
Again, your approach is risky with term expansion. Get more than 1,024 unique kcfileupload values and you'll see!
Erik
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" <[EMAIL PROTECTED]> 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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