Luke: a sorted search ignores exactHitsCount, so a sorted Search-tab query with more than 1,000 hits shows a lower-bound total ('1001+ hits') although the Sort tab forces 'exact hits count' on

Finding LFV-1036Area: luke / Search model, sorted search (SearchImpl.search) behind the Luke Search tabPriority: lowImpact: minorNovelty: new

Finding page for LFV-1036

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

What it shows

You open an index in Luke, pick a sort field in the Sort tab (Luke then ticks and greys out 'exact hits count') and run a search that matches more than 1,000 documents; you expect the exact total, as the javadoc of the Sort overload of Search.search promises ('if set to true, the exact total hits count is returned'). Instead Luke shows a lower bound such as '1001+ hits', and there is no way to get the exact count of a sorted search. The cause is that SearchImpl.search() passes exactHitsCount only to the unsorted collector; the sorted branch calls IndexSearcher.searchAfter(after, query, pageSize, sort), which counts exactly only up to 1,000 hits.

Expected vs actual

• Expected: TotalHits(1001, EQUAL_TO), shown in Luke as "1001 hits".
• Actual: AssertionError: expected:<1001 hits> but was:<1001+ hits>, with assertions on and off, on main and 10.6.0.

Files

• src/org/apache/lucene/luke/models/search/TestSortedSearchExactHitsCount.java (JUnit test)

Run it

• Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
• Tested on Lucene main 645d4fe14a20 (2026-10-28): 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/luke/build/libs/lucene-luke-$V.jar
CP=$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.luke.models.search.TestSortedSearchExactHitsCount

The module(s) luke 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).

Files shown on the finding page

• TestSortedSearchExactHitsCount.java

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 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.