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From "Ard Schrijvers" <a.schrijv...@hippo.nl>
Subject RE: Auto Slop
Date Mon, 02 Jul 2007 15:43:35 GMT

> I just ran into an interesting problem today, and wanted to know if it
> was my understanding or Lucene that was out of whack -- right now I'm
> leaning toward a fault between the chair and the keyboard.
> 
> I attempted to do a simple phrase query using the StandardAnalyzer:
> "United States"

And you also analyzed this the particular field with this same StandardAnalyzer during indexing?
Sounds like you used another analyzer during creating the index

Regards Ard

> 
> Against my corpus of test documents, I got no results returned, which
> surprised me.  I know it's in there.
> 
> So, I ran this same query in Luke, and it also returned no results.
> 
> Luke explains:
>   PhraseQuery: boost=1.0000, slop=0
>   pos[0,1]
>   Term 0: field='contents' text='united'
>   Term 1: field='contents' text='states'
> 
> Now I know Lucene handles phrases, so I tried manually setting the
> slop to 1, given that there were two terms:  "United States"~1
> 
> ...and suddenly I got the results I was expecting!
> 
> In fact, after a little trial and error with larger phrases, I always
> get no results unless I *manually* specify at least slop value of the
> number of terms minus one.
> 
> Isn't this supposed to be the default behavior if no slop is 
> specified?
> 
> Lucene's standard analyzer, which clear knows the number of terms,
> should be able to deduce the minimum slop amount.  Why must it be
> manually specified?
> 
> Could I be missing some configuration setting, have a bad
> understanding of the query syntax, or is there a clever reason (like
> searching for encoding synonyms) that makes more sense as a default
> value for slop that I'm not seeing?
> 
> Many thanks to all that unravel my confusion.
> 
> -wls
> 
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