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From Walter Underwood <wun...@wunderwood.org>
Subject Re: "[VOTE] Lucene/Solr 4.3 Take 2 (RC2)"
Date Mon, 22 Apr 2013 00:34:45 GMT
Don't use a stemmer with edge ngrams.

Edge ngrams are a tool for matching the surface word. Stemmers are a tool for matching the
root. Those are logically incompatible transforms. 

wunder

On Apr 21, 2013, at 5:21 PM, Steve Rowe wrote:

> Karol has uncovered a bug introduced by LUCENE-4810 <https://issues.apache.org/jira/browse/LUCENE-4810>,
included in Lucene/Solr 4.3.0.
> 
> The problem is an interaction between the Morfologik stemmer, which can produce multiple
stems per input term, all but the first having a position increment of zero, and EdgeNGramTokenFilter,
which only outputs ngrams for input terms that are at least as long as the minimum configured
length, and passes through unchanged the position increment for the first ngram output for
any given input term.
> 
> So what happens in Karol's case is that "T." has the period stripped by StandardTokenizer,
then is stemmed by Morfologik to produce terms "to", "tom" and "tona".  The first term "to"
has a position increment of 1, but is not output by EdgeNGramTokenFilter, because it's length
is below the configured minimum of 3.  The second term "tom" is given a position increment
of 0 by Morfologik, and meets EdgeNGramTokenFilter's minimum length, so gets output, and since
it's the first output term for the input term "tom", the input position increment is left
as-is in the output term: 0.  That's how the first output term gets a position increment of
0.
> 
> Before LUCENE-4810 was committed and included in Lucene/Solr 4.3.0, EdgeNGramTokenFilter
indiscriminately set all output terms' position increments to 1, so that explains why this
behavior didn't occur with previously released versions.
> 
> I think the fix is a check in EdgeNGramTokenFilter when outputting the first term, that
the position increment is greater than 0, and if it's not, then it should be set it to 1.
> 
> Does anybody know if this could also be an issue for other filters?
> 
> I'll work on a patch for EdgeNGramTokenFilter.
> 
> Steve
> 
> On Apr 21, 2013, at 9:21 AM, Karol Sikora <karol.sikora@laboratorium.ee> wrote:
> 
>> hi,
>> 
>> I extracted minimal failing example, solr configs(schema, solrconfig.xml) and data
are in attached archive.
>> I try to import simple document:
>> [
>>    {
>>        "publisher": [
>>            "T. Gl\u00fccksberg"
>>        ],  
>>        "uid": "1000881" 
>>    }, 
>>    {
>>        "publisher": [
>>      "Ala a kota"
>>        ],
>>        "uid": "1000894"
>>    }
>> ]
>> first fails on copyfield destination publisher_hl with exception (trace: https://gist.github.com/anonymous/5429558),
second is added without any problems.
>> schema.xml is here: https://gist.github.com/anonymous/5429562
>> 
>> When someone will trying to reproduce this behaviour remember to copy libs related
with morfologik and icu filters.
>> 
>> This extracted example works fine with solr 4.0 - 4.2.1.
>> 
>> Regards,
>> Karol
>> 
>> 
>> 
>> W dniu 21.04.2013 09:03, Simon Willnauer pisze:
>>> hey karol,
>>> 
>>> can you reproduce this behaviour in a small test-case (curl command or
>>> something like this) that we can reproduce?
>>> 
>>> @solr guys any idea what this could be?
>>> 
>>> simon
>>> 
>>> On Sun, Apr 21, 2013 at 1:52 AM, Karol Sikora
>>> 
>>> <karol.sikora@laboratorium.ee>
>>> wrote:
>>> 
>>>> Hi all,
>>>> 
>>>> I have problem with solr 4.3 RC2 on my testing data for searching
>>>> application which i'm developing.
>>>> A lot of importing records fails with exception
>>>> "java.lang.IllegalArgumentException: first position increment must be >
0
>>>> (got 0)". On versions from early 4.0 to 4.2.1 all documents was added
>>>> successfully, so I'm thinking that something is broken in new release.
>>>> I'll try examine tomorrow what is broken.
>>>> 
>>>> 
>>>> Regards,
>>>> Karol
>>>> 
>>>> W dniu 20.04.2013 21:07, Andi Vajda pisze:
>>>> 
>>>> 
>>>>> On Sat, 20 Apr 2013, Simon Willnauer wrote:
>>>>> 
>>>>> 
>>>>>> Here is the RC:
>>>>>> 
>>>>>> 
>>>>>> http://people.apache.org/~simonw/staging_area/lucene-solr-4.3.0-RC2-rev1470054
>>>>>> 
>>>>>> 
>>>>>> happy voting...
>>>>>> 
>>>>>> here is my +1
>>>>>> 
>>>>> 
>>>>> PyLucene 4.3 builds and passes its tests.
>>>>> 
>>>>> +1 !
>>>>> 
>>>>> Andi..
>>>>> 
>>>>> ---------------------------------------------------------------------
>>>>> To unsubscribe, e-mail: 
>>>>> dev-unsubscribe@lucene.apache.org
>>>>> 
>>>>> For additional commands, e-mail: 
>>>>> dev-help@lucene.apache.org
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>> --
>>>> Karol Sikora
>>>> +48 781 493 788
>>>> 
>>>> Laboratorium EE
>>>> ul. Mokotowska 46A/23 | 00-543 Warszawa |
>>>> 
>>>> www.laboratorium.ee | www.laboratorium.ee/facebook
>>>> 
>>>> 
>>>> 
>>>> 
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>>>> 
>>>> 
>>>> 
>>> ---------------------------------------------------------------------
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>>> 
>>> 
>>> 
>> 
>> -- 
>> 
>> Karol Sikora
>> Kierownik Informatyczny Projektu CBN - Interfejs 2.0
>> +48 781 493 788
>> 
>> Laboratorium EE
>> ul. Mokotowska 46A/23 | 00-543 Warszawa |
>> 
>> www.laboratorium.ee | www.laboratorium.ee/facebook
> 
> 
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> 

--
Walter Underwood
wunder@wunderwood.org




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