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From Scott Ganyo <scott.ga...@etapestry.com>
Subject Re: query matching all documents
Date Wed, 21 May 2003 20:14:19 GMT
Yes.  You must use a dummy field.

(Isn't this in the FAQ?)

newsham@hotu.com wrote:

> Since this question has gone unanswered, should I assume that such a 
> query is not possible with the existing Lucene version?
>
> newsham@hotu.com wrote:
>
>>
>> Is there a query object which can match all documents?
>>
>> As an example, suppose my search supports zero or more search 
>> criteria.  Each criteria, if specified, is required to match the 
>> document.  If no criteria are specified, all documents should be 
>> returned.  Here's an example (NullQuery is an imaginary class which 
>> represents the query type I'm looking for):
>>
>> BooleanQuery query = new BooleanQuery();
>> query.add(new NullQuery(), true, false);
>> if (criteria1exists) {
>>  query.add(..., true, false);
>> }
>> if (criteria2exists) {
>>  query.add(..., true, false);
>> }
>>
>> Without line 2, if no criteria is specified, no documents will be 
>> returned.  Apparently, a boolean query with no boolean elements 
>> matches zero documents.  In my opinion, it would have made more sense 
>> for it to match all documents, since each boolean element represents 
>> a constraint, and no constraints implies all documents.  But for 
>> clarity, maybe there should be an AllQuery and a NoneQuery which 
>> match all documents and no documents respectively.
>>
>> But back to reality, is there a way to achieve this with the existing 
>> query classes?  I'd prefer not to add a dummy field to search by, as 
>> this is not efficient.
>>
>> Thanks,
>> Jim
>>
>>
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>
>
>
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-- 
If the world should blow itself up, the last audible voice would be that of an expert saying
it can't be done. - Peter Ustinov



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