MemoryIndex stores binaryValue() instead of IndexableField.storedValue(), so stored StringField/KeywordField values built from a String and stored IntField/LongField/FloatField/DoubleField values come back as binary bytes (Document.get and numericValue() return null), and a StoredField built from a StoredFieldDataInput is dropped (released since 9.6.0)

Finding LFV-330Area: memory / MemoryIndex stored fieldsPriority: 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 build a MemoryIndex from a document with StringField("id", "doc-1", Store.YES), a KeywordField(String, Store.YES) or an IntField("count", 5, Store.YES) and read it back through storedFields().document(0), expecting the same stored values IndexWriter returns, since MemoryIndex has supported stored fields since 9.5.0 (#11999). Instead MemoryIndex stores the field's binaryValue() rather than its storedValue(): the String comes back as its UTF-8 bytes, so Document.get("id") returns null, and the numbers come back as their sortable point bytes (IntField 5 as [80 00 00 05]), so numericValue() returns null. A StoredField built from a StoredFieldDataInput is not stored at all; the BytesRef constructors and plain StoredField values are unaffected.

The test shows that MemoryIndex stores a StringField(String, Store.YES) as its term bytes (binaryValue()) instead of its storedValue(), so the stored String is lost.

Expected vs actual

Expected: storedFields().document(0).get("id") is "doc-1", as with IndexWriter. Actual: null.

Files

src/org/apache/lucene/index/memory/TestMemoryIndexStoredStringField.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/memory/build/libs/lucene-memory-$V.jar
CP=$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.index.memory.TestMemoryIndexStoredStringField

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.