UkrainianMorfologikAnalyzer overrides neither normalize() nor initReaderForNormalization, so prefix, wildcard, regexp, range and fuzzy terms from the query parsers skip its lower-casing and its apostrophe, stress-mark, soft-hyphen and ґ mapping and miss words spelled exactly as in the document

Finding LFV-557Area: analysis-morfologik / language analyzers (UkrainianMorfologikAnalyzer normalization: Analyzer#normalize and initReaderForNormalization, used by the query parsers for multi-term queries)Priority: mediumImpact: silent wrong resultsNovelty: new

Finding page for LFV-557

AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.

What it shows

You index Ukrainian text with UkrainianMorfologikAnalyzer, which maps typographic apostrophes to ', removes stress marks and soft hyphens, maps ґ to г and lower-cases every token before lemmatizing, so the document 'м’ясо Lucene' is stored as the terms м'ясо and lucene. A prefix, wildcard, regexp, range or fuzzy query built by a query parser sends its term through Analyzer.normalize, documented to return 'the representation that it would have in the index', but this analyzer overrides neither normalize(String, TokenStream) nor initReaderForNormalization, so normalize returns the text unchanged. As a result 'м’яс*', 'Luc*', 'Luce?e' and '[Lucene TO Lucene]' find nothing while "м'яс*" and 'luc*' find the document, and normalize("Lucene") returns 'Lucene' although the index holds 'lucene'.

UkrainianMorfologikAnalyzer.normalize skips the apostrophe mapping its initReader applies, so normalize("f", "м’ясо") (with U+2019) differs from the indexed term.

Expected vs actual

Expected "м'ясо" (the term the index holds), actual "м’ясо" (input unchanged): expected:<м[']ясо> but was:<м[’]ясо>.

Files

• src/org/apache/lucene/analysis/uk/TestUkrainianAnalyzerNormalizeApostrophe.java (JUnit test)

Run it

• Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
• Tested on Lucene main 645d4fe14a20 (2026-10-28): reproduced.
• Recorded outcome of run 1 on Lucene main 645d4fe14a20: 1 test(s) run, 1 failed.
• How to read the outcome: a failing test is the finding reproducing (the failure message states expected against actual).
• Seeds: a rerun with the same seed replays the same random choices. Assertions off (-da -dsa -Dtests.asserts=false) is the production-like setting.

# Lucene checkout at the tested commit, built with: ./gradlew --no-daemon assemble   (JDK 25)
LUCENE=/path/to/lucene; V=12.0.0-SNAPSHOT
CP=$LUCENE/lucene/core/build/libs/lucene-core-$V.jar
CP=$CP:$LUCENE/lucene/codecs/build/libs/lucene-codecs-$V.jar
CP=$CP:$LUCENE/lucene/test-framework/build/libs/lucene-test-framework-$V.jar
CP=$CP:$LUCENE/lucene/analysis/common/build/libs/lucene-analysis-common-$V.jar
CP=$CP:$LUCENE/lucene/analysis/morfologik/build/libs/lucene-analysis-morfologik-$V.jar
CP=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$CP:junit-platform-console-standalone-6.1.3.jar   # JUnit Platform console launcher (Maven Central)

javac -d classes -cp "$CP" $(find src -name '*.java')

# run 1: assertions on, seed DEADBEEF
java -ea -esa --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=DEADBEEF \
     -cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
     execute --select-class org.apache.lucene.analysis.uk.TestUkrainianAnalyzerNormalizeApostrophe

The module(s) analysis-morfologik also need their third-party runtime jars; ./gradlew -p lucene/<module> dependencies lists them.

Gradle alternative: copy the test into the matching module's src/test/ tree of the checkout and run ./gradlew -p lucene/<module> test --tests <class> -Ptests.seed=<seed> (add -Ptests.asserts=false for a run without assertions).

Feedback

Open an issue in lucene-ai-bug-hunt. Please do not open issues or pull requests in apache/lucene about this finding unless a Lucene committer agrees it should be filed.

Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.