Multi-valued range facet counts drop matches when a document's values do not arrive in ascending order (custom MultiLongValuesSource/MultiDoubleValuesSource, or raw-bit doubles with two or more negative values): LongRangeCounter.addMultiValued assumes sorted values

Finding LFV-303Area: facet / range facet counts (LongRangeCounter multi-valued path, exclusive and overlapping counters)Priority: mediumImpact: silent wrong resultsNovelty: new

Finding page for LFV-303

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

What it shows

You compute range facet counts over a multi-valued source, for example the distances from the user to each of a document's locations computed by your own MultiDoubleValuesSource, or doubles stored as raw bits in a SortedNumeric field and read with fromDoubleField or the DoubleRangeFacetCounts(String, ...) constructor. You expect each range to count every document that has at least one value in it, which is exactly what the range's own drill-down query finds. Instead, when a document's values arrive in descending order (a custom source in its natural order, or raw-bit doubles whenever the document has two or more negative values), the counter skips every later value that sorts below an interval it already counted for that document, so a document with distances {3.0, 0.5} is missing from '< 1 km' and '< 2 km'.

The test shows that LongRangeFacetCounts drops a match when a custom MultiLongValuesSource gives one doc the values {30, 5} (not ascending): LongRangeCounter.addMultiValued skips 5 after counting 30.

Expected vs actual

Expected count 1 for range [0, 10) (the range's own drill-down query finds the doc); actual 0 (-ea and -da).

Files

• src/org/apache/lucene/facet/range/TestRangeFacetUnsortedMultiValues.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/facet/build/libs/lucene-facet-$V.jar
CP=$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.facet.range.TestRangeFacetUnsortedMultiValues

The module(s) facet 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).

Formal models and scripts this finding's part of the hunt used: facet-taxonomy-ranges

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.