[LUCENE-9173] SynonymGraphFilter doesn't correctly consume decompounded tokens (branched token graph)

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: modules/analysis
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Tomoko Uchida
• Created: 26/Jan/20 09:59
• Updated: 28/Aug/22 15:56

Description

This is a derived issue from LUCENE-9123.

When the tokenizer that is given to SynonymGraphFilter decompound tokens or emit multiple tokens at the same position, SynonymGraphFilter cannot correctly handle them (an exception will be thrown).

For example, JapaneseTokenizer (mode=SEARCH) would emit a token and two decompounded tokens for the text "株式会社":

株式会社 (positionIncrement=0, positionLength=2)
株式 (positionIncrement=1, positionLength=1)
会社 (positionIncrement=1, positionLength=1)

Then if we give a synonym "株式会社,コーポレーション" by SynonymGraphFilterFactory (set tokenizerFactory=JapaneseTokenizerFactory) this exception is thrown.

Caused by: java.lang.IllegalArgumentException: term: 株式会社 analyzed to a token (株式会社) with position increment != 1 (got: 0)
	at org.apache.lucene.analysis.synonym.SynonymMap$Parser.analyze(SynonymMap.java:325) ~[lucene-analyzers-common-8.4.0.jar:8.4.0 bc02ab906445fcf4e297f4ef00ab4a54fdd72ca2 - jpountz - 2019-12-19 20:16:38]
	at org.apache.lucene.analysis.synonym.SolrSynonymParser.addInternal(SolrSynonymParser.java:114) ~[lucene-analyzers-common-8.4.0.jar:8.4.0 bc02ab906445fcf4e297f4ef00ab4a54fdd72ca2 - jpountz - 2019-12-19 20:16:38]
	at org.apache.lucene.analysis.synonym.SolrSynonymParser.parse(SolrSynonymParser.java:70) ~[lucene-analyzers-common-8.4.0.jar:8.4.0 bc02ab906445fcf4e297f4ef00ab4a54fdd72ca2 - jpountz - 2019-12-19 20:16:38]
	at org.apache.lucene.analysis.synonym.SynonymGraphFilterFactory.loadSynonyms(SynonymGraphFilterFactory.java:179) ~[lucene-analyzers-common-8.4.0.jar:8.4.0 bc02ab906445fcf4e297f4ef00ab4a54fdd72ca2 - jpountz - 2019-12-19 20:16:38]
	at org.apache.lucene.analysis.synonym.SynonymGraphFilterFactory.inform(SynonymGraphFilterFactory.java:154) ~[lucene-analyzers-common-8.4.0.jar:8.4.0 bc02ab906445fcf4e297f4ef00ab4a54fdd72ca2 - jpountz - 2019-12-19 20:16:38]

This isn't only limited to JapaneseTokenizer but a more general issue about handling branched token graph (decompounded tokens in the midstream).

Issue Links

• relates to: LUCENE-9123 JapaneseTokenizer with search mode doesn't work with SynonymGraphFilter