FunctionRangeQuery scores a document with its raw, possibly negative, function value although LUCENE-7996 forbids negative scores and FunctionQuery over the same source clamps them to 0; since 10.1.0 a matching document whose value is -Infinity can then disappear from the top-k results of a minimumShouldMatch >= 2 BooleanQuery

Finding LFV-406Area: queries / function queries (ValueSourceScorer behind FunctionRangeQuery, LUCENE-7996 non-negative score rule; the hit loss surfaces in core WANDScorer)Priority: lowImpact: silent wrong resultsNovelty: new

Finding page for LFV-406

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 a document with DoubleDocValuesField("d", -5.0) and search new FunctionRangeQuery(new DoubleFieldSource("d"), -10.0, 10.0, true, true), expecting a non-negative score, because since LUCENE-7996 (8.0) scorers must not produce negative scores and FunctionQuery over the same source scores that document 0. Instead it scores -5.0 (-Infinity and NaN become -Float.MAX_VALUE), because ValueSourceScorer.score() returns the raw value and LUCENE-7996 clamped FunctionQuery, BoostedQuery and FunctionScoreQuery but not this scorer. Since 10.1.0 this also loses hits: with minimumNumberShouldMatch = 2 over SHOULD clauses FunctionRangeQuery(d, open range), body:a and body:b (sparse term clauses; also dense ones since 10.5.0), a matching document whose value is -Infinity is missing from search(q, 10), whose totalHits says '3 hits' while count(q) is 4, because WANDScorer rejects a candidate whose scaled score is below the initial minimum competitive score of 0.

The test shows that FunctionRangeQuery scores a document with its raw negative value (-Infinity becomes -Float.MAX_VALUE), so a minimumNumberShouldMatch = 2 BooleanQuery drops that matching document from top-k results.

Expected vs actual

Expected search(q, 10) to return all count(q) = 2 matches; actual: 1 (expected:<2> but was:<1>) with -da. With -ea the search throws AssertionError at WANDScorer.scaleMaxScore (assert maxScore >= 0).

Files

• src/org/apache/lucene/queries/function/TestFunctionRangeQueryNegativeScoreHitLoss.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/queries/build/libs/lucene-queries-$V.jar
CP=$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.queries.function.TestFunctionRangeQueryNegativeScoreHitLoss

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.