apache/druid · error · IllegalStateException

Cannot return null value as double

Error message

Cannot return null value as double

What it means

NilColumnValueSelector represents a column whose every value is null. Since primitives cannot be null in Java, getDouble() throws IllegalStateException instead of returning a value. Callers must check isNull()/getObject() before requesting primitive access on a null column.

Solutions

1. Check selector.isNull() or use getObject() and handle null before calling getDouble()
2. Ensure the queried column exists in the datasource/segment (verify with SegmentMetadataQuery)
3. Use default value handling in the query (e.g. SQL COALESCE) so missing columns are substituted
4. If ingesting, supply a default for the numeric field in the ingestion spec

Example fix

// before
double d = selector.getDouble();
// after
Object val = selector.isNull() ? null : selector.getObject();
double d = val == null ? 0.0 : ((Number) val).doubleValue();

if (selector.getObject() == null) { /* treat as missing */ }

Double safeGetDouble(ColumnValueSelector<?> s) { return s.isNull() ? null : s.getDouble(); }

try {
  double d = selector.getDouble();
} catch (IllegalStateException e) {
  double d = 0.0; // default for null column
}

When it happens

Trigger: Calling getDouble() on a column selector created by NilColumnValueSelector — e.g. querying a numeric column that does not exist in a row/segment, or accessing a typed selector on rows lacking the value.

Common situations: Queries against datasources where a numeric column is absent in some segments; row-based ingestion where rows omit a numeric field; misconfigured query columns pointing at nonexistent metrics.

Related errors

• Cannot return null value as float
• Cannot return null value as long
• A table definition must include a table spec.
• Could not transform value for __time.
• Unexpected null value in BloomFilterMergeAggregator

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/fc44748d36dc2b8a. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/segment/NilColumnValueSelector.java:50

{
  private static final NilColumnValueSelector INSTANCE = new NilColumnValueSelector();

  public static NilColumnValueSelector instance()
  {
    return INSTANCE;
  }

  private NilColumnValueSelector()
  {
  }

  /**
   * always throws an exception, all values in this column are null
   */
  @Override
  public double getDouble()
  {
    throw new IllegalStateException("Cannot return null value as double");
  }

  /**
   * always throws an exception, all values in this column are null
   */
  @Override
  public float getFloat()
  {
    throw new IllegalStateException("Cannot return null value as float");
  }

  /**
   * always throws an exception, all values in this column are null
   */
  @Override
  public long getLong()
  {
    throw new IllegalStateException("Cannot return null value as long");

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