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From Jonathan Rochkind <>
Subject Re: lucene parser, negative OR operands
Date Thu, 19 May 2011 14:25:30 GMT
On 5/18/2011 9:07 PM, Chris Hostetter wrote:
> You could implement a parser like that relatively easily -- just make sure
> you put a MatchAllDocsQuery in every BooleanQuery object thta you
> construct, and only ever use the PROHIBITED and MANDATORY clause types
> (never OPTIONAL) ...  the thing is, a parser like that isn't as useful
> as you think it might be when dealing with search results.  "OPTIONAL"
> clauses are where most of the useful factors of scoring documents ocme
> into play.

Thanks for the background and ideas, very helpful.

Hmm, but what if it DID use OPTIONAL clause types.... but just turned 
all pure-negative clauses into the alternative combination with 
MatchAllDocsQuery ( "*:* AND $pure_negative")?  Just like lucene query 
parser does now, but not only for top-level clauses. Seems like that 
might maintain the power of optional clauses for scoring, but still 
allow negative clauses to work the 'boolean logic' way people expect -- 
same rationale that has the query parser doing this at top-level, why 
not do it for sub-clauses as well? Does that have any promise do you think?


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