[LUCENE-9123] JapaneseTokenizer with search mode doesn't work with SynonymGraphFilter

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 9.0, 8.5
• Component/s: modules/analysis
• Lucene Fields: New
• Assignee: Tomoko Uchida
• Reporter: Kazuaki Hiraga
• Created: 09/Jan/20 06:41
• Updated: 28/Aug/22 15:55
• Resolved: 01/Feb/20 06:30

Description

JapaneseTokenizer with `mode=search` or `mode=extended` doesn't work with both of SynonymGraphFilter and SynonymFilter when JT generates multiple tokens as an output. If we use `mode=normal`, it should be fine. However, we would like to use decomposed tokens that can maximize to chance to increase recall.

Snippet of schema:

    <fieldType name="text_custom_ja" class="solr.TextField" positionIncrementGap="100" autoGeneratePhraseQueries="false">
      <analyzer>
        <tokenizer class="solr.JapaneseTokenizerFactory" mode="search"/>
        <filter class="solr.SynonymGraphFilterFactory"
                    synonyms="lang/synonyms_ja.txt"
                    tokenizerFactory="solr.JapaneseTokenizerFactory"/>

        <filter class="solr.JapaneseBaseFormFilterFactory"/>
        <!-- Removes tokens with certain part-of-speech tags -->
        <filter class="solr.JapanesePartOfSpeechStopFilterFactory" tags="lang/stoptags_ja.txt" />
        <!-- Normalizes full-width romaji to half-width and half-width kana to full-width (Unicode NFKC subset) -->
        <filter class="solr.CJKWidthFilterFactory"/>
        <!-- Removes common tokens typically not useful for search, but have a negative effect on ranking -->
        <!-- <filter class="solr.StopFilterFactory" ignoreCase="true" words="lang/stopwords_ja.txt" /> -->
        <!-- Normalizes common katakana spelling variations by removing any last long sound character (U+30FC) -->
        <filter class="solr.JapaneseKatakanaStemFilterFactory" minimumLength="4"/>
        <!-- Lower-cases romaji characters -->
        <filter class="solr.LowerCaseFilterFactory"/>
      </analyzer>
    </fieldType>

An synonym entry that generates error:

株式会社,コーポレーション

The following is an output on console:

$ ./bin/solr create_core -c jp_test -d ../config/solrconfs

ERROR: Error CREATEing SolrCore 'jp_test': Unable to create core [jp_test3] Caused by: term: 株式会社 analyzed to a token (株式会社) with position increment != 1 (got: 0)

Issue Links

• is related to: LUCENE-9173 SynonymGraphFilter doesn't correctly consume decompounded tokens (branched token graph)
• is related to: SOLR-14295 Add the parameter description about "discardCompoundToken" for JapaneseTokenizer