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From "Christian Moen (Commented) (JIRA)" <>
Subject [jira] [Commented] (SOLR-3056) Introduce Japanese field type in schema.xml
Date Wed, 01 Feb 2012 16:58:58 GMT


Christian Moen commented on SOLR-3056:

Robert, Let's enable stop-words and stop-tags by default.

The stopwords list in the Lucene analyzer looks too small unless it's always used in combination
with a stoptags filter.  I'll look into both of these.

Also, if we're using search mode, part-of-speech F will decrease so we might want to rely
more on stopwords rather than stoptags if it goes down by a whole lot.  However, since tokens
agree in 99.7% of the cases based on the tests I did earlier and the part-of-speech tags we'd
typically use as stop tags aren't involved with tokens split by search mode, I don't expect
this to be a real issue, but it's something to keep in mind.

I'll do some testing to verify this and I'll follow up with further improvements to configuration.

I'll also open up a separate JIRA for stopwords and stoptags, and aligning the Solr and Lucene
default configuration.
> Introduce Japanese field type in schema.xml
> -------------------------------------------
>                 Key: SOLR-3056
>                 URL:
>             Project: Solr
>          Issue Type: New Feature
>          Components: Schema and Analysis
>    Affects Versions: 3.6, 4.0
>            Reporter: Christian Moen
>         Attachments: SOLR-3056_move.patch, SOLR-3056_schema40.patch, SOLR-3056_schema40.patch
> Kuromoji (LUCENE-3305) is now on both on trunk and branch_3x (thanks again Robert, Uwe
and Simon). It would be very good to get a default field type defined for Japanese in {{schema.xml}}
so we can good Japanese out-of-the-box support in Solr.
> I've been playing with the below configuration today, which I think is a reasonable starting
point for Japanese.  There's lot to be said about various considerations necessary when searching
Japanese, but perhaps a wiki page is more suitable to cover the wider topic?
> In order to make the below {{text_ja}} field type work, Kuromoji itself and its analyzers
need to be seen by the Solr classloader.  However, these are currently in contrib and I'm
wondering if we should consider moving them to core to make them directly available.  If there
are concerns with additional memory usage, etc. for non-Japanese users, we can make sure resources
are loaded lazily and only when needed in factory-land.
> Any thoughts?
> {code:xml}
> <!-- Text field type is suitable for Japanese text using morphological analysis
>      NOTE: Please copy files
>        contrib/analysis-extras/lucene-libs/lucene-kuromoji-x.y.z.jar
>        dist/apache-solr-analysis-extras-x.y.z.jar
>      to your Solr lib directory (i.e. example/solr/lib) before before starting Solr.
>      (x.y.z refers to a version number)
>      If you would like to optimize for precision, default operator AND with
>        <solrQueryParser defaultOperator="AND"/>
>      below (this file).  Use "OR" if you would like to optimize for recall (default).
> -->
> <fieldType name="text_ja" class="solr.TextField" positionIncrementGap="100" autoGeneratePhraseQueries="false">
>   <analyzer>
>     <!-- Kuromoji Japanese morphological analyzer/tokenizer
>          Use search-mode to get a noun-decompounding effect useful for search.
>          Example:
>            関西国際空港 (Kansai International Airpart) becomes 関西 (Kansai)
国際 (International) 空港 (airport)
>            so we get a match for 空港 (airport) as we would expect from a good search
>          Valid values for mode are:
>             normal: default segmentation
>             search: segmentation useful for search (extra compound splitting)
>           extended: search mode with unigramming of unknown words (experimental)
>          NOTE: Search mode improves segmentation for search at the expense of part-of-speech
>     -->
>     <tokenizer class="solr.KuromojiTokenizerFactory" mode="search"/>
>     <!-- Reduces inflected verbs and adjectives to their base/dectionary forms (辞書形)
>     <filter class="solr.KuromojiBaseFormFilterFactory"/>
>     <!-- Optionally remove tokens with certain part-of-speeches
>     <filter class="solr.KuromojiPartOfSpeechStopFilterFactory" tags="stopTags.txt"
enablePositionIncrements="true"/> -->
>     <!-- Normalizes full-width romaji to half-with and half-width kana to full-width
(Unicode NFKC subset) -->
>     <filter class="solr.CJKWidthFilterFactory"/>
>     <!-- Lower-case romaji characters -->
>     <filter class="solr.LowerCaseFilterFactory"/>
>   </analyzer>
> </fieldType>
> {code}

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