apache/iceberg · error · UnsupportedOperationException

Unsupported RawType.

Error message

Unsupported RawType.

What it means

FlinkTypeVisitor.visit(RawType) throws UnsupportedOperationException because Iceberg cannot store Flink RAW types (opaque serialized user objects). Conversion fails rather than serializing values opaquely into the Iceberg schema.

Solutions

1. Convert the RAW column to a concrete SQL type (STRING, BINARY, ROW<...>) before writing to Iceberg.
2. Have the UDF return a supported type or declare an explicit result DataType.
3. Serialize the object to JSON/Avro bytes into a STRING/BINARY column.

Example fix

// before
column RAW<'com.acme.Payload', 'com.acme.PayloadSerde'> payload;
// after
column STRING payload; // JSON-serialized payload

if (dataType.getLogicalType() instanceof RawType) {
  throw new IllegalArgumentException("Convert RAW columns to SQL types (STRING/BINARY/ROW) before Iceberg write");
}

When it happens

Trigger: Schema conversion over a column typed RAW('class','serializer') — usually produced by UDFs returning user objects or TypeInformation-based RAW columns.

Common situations: UDF outputs or connector columns using custom Java objects without mapping to SQL types, then landing in Iceberg sink table definitions.

Understand the failure class

Background: "is not a compatible type" / "cannot merge" errors: when a value's type doesn't match what the library requires — this error's family across 65 libraries.

Related errors

• Unsupported RawType.
• Unsupported DayTimeIntervalType.
• Unsupported DayTimeIntervalType.
• Unsupported DistinctType.
• Unsupported DistinctType.

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/cc31acfe50e589e4. Report an issue: GitHub.

Appendix: source

Thrown at flink/v2.2/flink/src/main/java/org/apache/iceberg/flink/FlinkTypeVisitor.java:68

  @Override
  public T visit(DistinctType distinctType) {
    throw new UnsupportedOperationException("Unsupported DistinctType.");
  }

  @Override
  public T visit(StructuredType structuredType) {
    throw new UnsupportedOperationException("Unsupported StructuredType.");
  }

  @Override
  public T visit(NullType nullType) {
    throw new UnsupportedOperationException("Unsupported NullType.");
  }

  @Override
  public T visit(RawType<?> rawType) {
    throw new UnsupportedOperationException("Unsupported RawType.");
  }

  @Override
  public T visit(SymbolType<?> symbolType) {
    throw new UnsupportedOperationException("Unsupported SymbolType.");
  }

  @Override
  public T visit(LogicalType other) {
    throw new UnsupportedOperationException("Unsupported type: " + other);
  }
}

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