apache/iceberg · error · UnsupportedOperationException

Failed to read Variant

Error message

Failed to read Variant %s of type %s as %s

What it means

VariantRowDataWrapper.intValue narrows a Variant to an int, accepting TINYINT, SMALLINT and INT variants; anything else throws UnsupportedOperationException with errMsg(variant, "int"): "Failed to read Variant <value> of type <type> as int". Raised when the Variant's actual type cannot losslessly be read as an int.

Solutions

1. Declare the Flink field as BIGINT (and use getLong) if values exceed int range.
2. Fix the writer so Variant values written for int columns are of type INT.
3. Cast the Variant value in the query to a numeric type before int access.

Example fix

// before
DataTypes.FIELD("n", DataTypes.INT()) // variant holds BIGINT

// after
DataTypes.FIELD("n", DataTypes.BIGINT())

Variant v = ...;
if (!(v.getType() == Variant.Type.TINYINT || v.getType() == Variant.Type.SMALLINT || v.getType() == Variant.Type.INT)) {
  throw new IllegalArgumentException("Variant not int-typed: " + v.getType());
}

boolean isIntVariant(Variant v) {
  switch (v.getType()) {
    case TINYINT: case SMALLINT: case INT: return true;
    default: return false;
  }
}

try {
  int i = rowData.getInt(pos);
} catch (UnsupportedOperationException e) {
  // widen the column to BIGINT or convert the variant value upstream
}

When it happens

Trigger: getInt(pos) or elementValue(...) with an INT LogicalType encountering a Variant of type BIGINT, DOUBLE, STRING, BOOLEAN, etc.

Common situations: Schema/type mismatch where the Flink column declares INT but the stored Variant holds a wider number or a string; mixed-typed arrays/maps with int element declarations.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• errMsg(variant, "double")
• errMsg(variant, "int")
• errMsg(variant, "long")
• errMsg(variant, "timestamp")
• Failed to read Variant

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/85247dc54a84358b. Report an issue: GitHub.

Appendix: source

Thrown at flink/v2.3/flink/src/main/java/org/apache/iceberg/flink/data/VariantRowDataWrapper.java:255

    }

    int arraySize = BinaryVariantAccessorUtils.arraySize(variant);
    Object[] elements = new Object[arraySize];

    for (int i = 0; i < arraySize; i++) {
      Variant element = variant.getElement(i);
      elements[i] = elementValue(element, innerElementType);
    }

    return new GenericArrayData(elements);
  }

  private static int intValue(Variant variant) {
    return switch (variant.getType()) {
      case TINYINT -> variant.getByte();
      case SMALLINT -> variant.getShort();
      case INT -> variant.getInt();
      default -> throw new UnsupportedOperationException(errMsg(variant, "int"));
    };
  }

  private static long longValue(Variant variant) {
    return switch (variant.getType()) {
      case TINYINT -> variant.getByte();
      case SMALLINT -> variant.getShort();
      case INT -> variant.getInt();
      case BIGINT -> variant.getLong();
      default -> throw new UnsupportedOperationException(errMsg(variant, "long"));
    };
  }

  private static double doubleValue(Variant variant) {
    return switch (variant.getType()) {
      case FLOAT -> variant.getFloat();
      case DOUBLE -> variant.getDouble();
      default -> throw new UnsupportedOperationException(errMsg(variant, "double"));

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