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From "Robert Muir (JIRA)" <j...@apache.org>
Subject [jira] Created: (LUCENE-2780) optimize spantermquery
Date Thu, 25 Nov 2010 20:29:13 GMT
optimize spantermquery
----------------------

                 Key: LUCENE-2780
                 URL: https://issues.apache.org/jira/browse/LUCENE-2780
             Project: Lucene - Java
          Issue Type: Improvement
          Components: Search
            Reporter: Robert Muir
             Fix For: 3.1, 4.0


Looking at http://www.lucidimagination.com/search/document/c2c6f660ddde4f7f/dismaxqparserplugin_and_tokenization
,
I saw a user building DisjunctionMaxQuery / BooleanQuery with SpanTermQuerys.

I wonder if users know that doing this is much slower than just using TermQuery?
I agree it makes little sense to use SpanTermQuery if you arent going to use it inside a SpanNear
etc,
but on the other hand, I think its a little non-intuitive that it wouldnt be just as fast
in a case like this.

I could see this complicating queryparsing etc for users that want to sometimes use positions
etc.

SpanTermQuery is the same as TermQuery, except tf is computed as (#of spans * sloppyFreq(spanLength)
For this case, #ofspans = tf and spanLength for a single term is always 1.

Maybe we should optimize SpanTermQuery to return TermScorer, with just this special tf computation.
This would avoid reading positions for anyone that does this.



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