JoinUtil's numeric join reads a DoubleField or FloatField from field as raw IEEE bits, so a join on a negative value silently misses its matches

Finding LFV-1111Area: join / JoinUtil numeric (point-based) query-time join: multi-valued Float/Double decode of core DoubleField/FloatField doc valuesPriority: mediumImpact: silent wrong resultsNovelty: new

Finding page for LFV-1111

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 one from document with DoubleField("from", -5.0) and one to document with DoubleField("to", -5.0), and count JoinUtil.createJoinQuery("from", true, "to", Double.class, new MatchAllDocsQuery(), fromSearcher, ScoreMode.None) on the to index; you expect 1, because the javadoc lists floats and doubles and allows SORTED_NUMERIC from fields, which is what DoubleField writes. You get 0 with no error: DoubleField stores NumericUtils.doubleToSortableLong(-5.0), but JoinUtil's multi-valued Float/Double path decodes the stored long as raw IEEE bits (Double.longBitsToDouble, Float.intBitsToFloat), so the join looks up -0.8749999999999999 instead of -5.0. Positive values are unaffected because their sortable and raw bits are the same, and FloatField fails the same way.

Expected vs actual

• Expected: 1 hit: the document's from value -5.0 matches its own point -5.0.
• Actual: 0 hits, no error: AssertionError: expected:<1> but was:<0>, with assertions on and off.

Files

• src/org/apache/lucene/search/join/TestJoinNegativeDoubleField.java (JUnit test)

Run it

• Tested on Lucene main e1faeba08bde (2026-11-02): reproduced.
• 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/join/build/libs/lucene-join-$V.jar
CP=$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, default flags
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.search.join.TestJoinNegativeDoubleField

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).

Files shown on the finding page

• TestJoinNegativeDoubleField.java

Formal models and scripts this finding's part of the hunt used: sortednumeric-double-float-sortable-vs-raw-decoding-facet-and-join

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.