Geo3D distance, path and outside-distance sorts (Geo3DDocValuesField) drop hits under IndexSearcher.searchAfter: compareTop compares the cursor, which is in meters, with the document's distance in planet units, so on WGS84 every page after the first loses all finite-distance hits (released since 6.1.0)
Finding LFV-544Area: spatial3d / Geo3DDocValuesField sort comparators (Geo3DPointDistanceComparator, Geo3DPointOutsideDistanceComparator: compareTop under searchAfter paging)Priority: mediumImpact: silent wrong resultsNovelty: new
AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.
What it shows
You sort by Geo3DDocValuesField.newDistanceSort (or the path or outside-distance sorts) on the default WGS84 planet model, take the last FieldDoc of page 1 and call IndexSearcher.searchAfter(last, query, n, sort), expecting the next hits in distance order, as searchAfter documents. Instead the comparator's value() returns the distance in meters (as the factories' javadoc says), but compareTop compares that meters cursor with the document's distance in planet units (distances on a planet of mean radius 1), so every document with a finite distance looks 'already collected on a previous page' and is skipped. With six documents 3 to 8 degrees north of the origin and page size 2, page 2 should be [2, 3, 4, 5] and is []; on PlanetModel.SPHERE, where meters and planet units coincide, the same paging is correct.
The test shows that paging a Geo3D distance sort (Geo3DDocValuesField.newDistanceSort, WGS84) with IndexSearcher.searchAfter loses hits: the cursor is in meters but compareTop compares it with the planet-unit distance.
Expected vs actual
Two points, page size 1: expected page 2 = [doc 1]; actual: no hits (hits on page 2 expected:<1> but was:<0>), with -ea and -da.
Files
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/spatial3d/build/libs/lucene-spatial3d-$V.jar
CP=$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.spatial3d.TestGeo3DDistanceSortSearchAfterGradle 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.