apache/druid · error · java.lang.UnsupportedOperationException

attempt to get boolean[] null vector from string[] only scal

Error message

attempt to get boolean[] null vector from string[] only scalar binding

What it means

The getNullVector accessor of the string-only input bindings is also unsupported: null bitmaps for the single string input are provided via other accessors, and any request for a boolean[] null vector throws UnsupportedOperationException.

Source

Thrown at processing/src/main/java/org/apache/druid/segment/virtual/SingleStringInputDeferredEvaluationExpressionDimensionVectorSelector.java:171

    }

    @Override
    public long[] getLongVector(String name)
    {
      throw new UnsupportedOperationException("attempt to get long[] from string[] only scalar binding");
    }

    @Override
    public double[] getDoubleVector(String name)
    {
      throw new UnsupportedOperationException("attempt to get double[] from string[] only scalar binding");
    }

    @Nullable
    @Override
    public boolean[] getNullVector(String name)
    {
      throw new UnsupportedOperationException("attempt to get boolean[] null vector from string[] only scalar binding");
    }
  }
}

View on GitHub (pinned to 9b90983fd2)

Solutions

Use getStringVector and its companion null handling instead of getNullVector for this binding
Adjust the expression to handle nulls via string-level functions (e.g. coalesce on string)
Disable vectorization as a workaround
Avoid custom expressions that require typed null vectors against string-only bindings

Example fix

// before
// expression calls bindings.getNullVector(name)
// after
// use bindings.getStringVector(name) and treat null/empty strings per expression semantics

Defensive patterns

Strategy: try-catch

Validate before calling

// do not request getNullVector from string-only bindings; use getStringVector null semantics instead

Try / catch

try {
  boolean[] nulls = bindings.getNullVector(name);
} catch (UnsupportedOperationException e) {
  // derive nulls from getStringVector contents instead
}

Prevention

Use getStringVector plus per-row null checks for string-only bindings
Avoid expressions that unconditionally request typed null vectors
Disable vectorization when expressions need typed null vector access

When it happens

Trigger: Vector engine or expression evaluation calls getNullVector(name) on the bindings created by SingleStringInputDeferredEvaluationExpressionDimensionVectorSelector.

Common situations: Vectorized expressions with nullable-typed inputs over string columns; custom expression nodes that unconditionally request null vectors.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/92739ac234be0743. Report an issue: GitHub.