apache/druid · error · IllegalStateException

written out already

Error message

written out already

What it means

V3CompressedVSizeColumnarMultiIntsSerializer serializes multi-valued int columns. Once the offsets stream has been finalized (`lastOffsetWritten` is true), no further rows may be added; addValues() throws this IllegalStateException to protect the already-committed serialization state.

Solutions

1. Ensure all rows are added before closing/finalizing the serializer
2. Create a fresh V3ComposedVSizeColumnarMultiIntsSerializer per column instead of reusing finished instances
3. Fix retry/error-handling logic that may re-call addValues after a successful close

Example fix

// before
serializer.close();
serializer.addValues(row); // throws
// after
serializer.close();
V3CompressedVSizeColumnarMultiIntsSerializer fresh = ...; // new serializer for new data
fresh.addValues(row);

if (!serializer.isClosed()) { serializer.addValues(row); } else { serializer = newSerializer(); serializer.addValues(row); }

try { serializer.addValues(ints); } catch (IllegalStateException e) { throw new IOException("multi-int column already finalized; open a new serializer", e); }

When it happens

Trigger: Calling addValues(IndexedInts) after the serializer was closed/finished; reusing the same serializer instance for a second column or file; aggregation feeding rows after finalization.

Common situations: Batch ingestion code that flushes a column then keeps appending rows; test harnesses reusing serializers across cases; error-handling paths that retry writes after close.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• Incompatible serializer for type
• written out already
• Actual Row count mismatch. Expected
• Attempt to add row to swapped-out sink for segment
• Column capacity exceeded

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/c0f5bd07ddefa3c1. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/segment/data/V3CompressedVSizeColumnarMultiIntsSerializer.java:113

  {
    this.columnName = columnName;
    this.offsetWriter = offsetWriter;
    this.valueWriter = valueWriter;
    this.offset = 0;
  }

  @Override
  public void open() throws IOException
  {
    offsetWriter.open();
    valueWriter.open();
  }

  @Override
  public void addValues(IndexedInts ints) throws IOException
  {
    if (lastOffsetWritten) {
      throw new IllegalStateException("written out already");
    }
    offsetWriter.addValue(offset);
    int numValues = ints.size();
    for (int i = 0; i < numValues; i++) {
      valueWriter.addValue(ints.get(i));
    }
    offset += numValues;
    if (offset < 0) {
      throw new ColumnCapacityExceededException(columnName);
    }
  }

  @Override
  public long getSerializedSize() throws IOException
  {
    writeLastOffset();
    return 1 + offsetWriter.getSerializedSize() + valueWriter.getSerializedSize();
  }

View on GitHub (pinned to 9b90983fd2)