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https://issues.apache.org/jira/browse/LUCENE-2230?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12830160#action_12830160
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Dirk Goldhan commented on LUCENE-2230:
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I have tried your patch on lucene 3.0.0. I had to make a small change to get it
work.
In the current implementation the enumerator is before the first element. This
is no problem in lucene 2.9.1 as it simply does one more iteration in
FuzzyQuery (rewrite). In lucene 3.0.0 FuzzyQuery directly accesses the first
element of the enumeration. As this is null it simply stops further processing
of terms (if (t == null) break;).
I have made a small change in the FuzzyTermEnumNEW class to assign the first
element to the enumerator during creation. I simply appended the following
lines within the constructor:
if (this.termIterator.hasNext()) {
Term firstTerm = new Term(field,
termMap.keySet().iterator().next());
this.currentTerm = firstTerm;
}
Thank you for the patch.
> Lucene Fuzzy Search: BK-Tree can improve performance 3-20 times.
> ----------------------------------------------------------------
>
> Key: LUCENE-2230
> URL: https://issues.apache.org/jira/browse/LUCENE-2230
> Project: Lucene - Java
> Issue Type: Improvement
> Affects Versions: 3.0
> Environment: Lucene currently uses brute force full-terms scanner and
> calculates distance for each term. New BKTree structure improves performance
> in average 20 times when distance is 1, and 3 times when distance is 3. I
> tested with index size several millions docs, and 250,000 terms.
> New algo uses integer distances between objects.
> Reporter: Fuad Efendi
> Attachments: BKTree.java, Distance.java, DistanceImpl.java,
> FuzzyTermEnumNEW.java, FuzzyTermEnumNEW.java
>
> Original Estimate: 0.02h
> Remaining Estimate: 0.02h
>
> W. Burkhard and R. Keller. Some approaches to best-match file searching,
> CACM, 1973
> http://portal.acm.org/citation.cfm?doid=362003.362025
> I was inspired by
> http://blog.notdot.net/2007/4/Damn-Cool-Algorithms-Part-1-BK-Trees (Nick
> Johnson, Google).
> Additionally, simplified algorythm at
> http://www.catalysoft.com/articles/StrikeAMatch.html seems to be much more
> logically correct than Levenstein distance, and it is 3-5 times faster
> (isolated tests).
> Big list od distance implementations:
> http://www.dcs.shef.ac.uk/~sam/stringmetrics.htm
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