What causes "[%s] is not supported in SUM0" in apache/beam?

Ensure the aggregated column's schema type is INTEGER, INT64, DOUBLE, or DECIMAL before the aggregation is planned.

apache/beam · error · UnsupportedOperationException

[ ] is not supported in SUM0

Error message

[%s] is not supported in SUM0

What it means

createSum0 builds the SUM0 aggregation (SUM where the sum of all-null input is 0 instead of NULL). It supports the same numeric types as SUM — INTEGER-family (FloatSum0/IntSum0), DOUBLE (DoubleSum0), DECIMAL (BigDecimalSum0) — and throws UnsupportedOperationException for any other field type.

Solutions

Ensure the aggregated column's schema type is INTEGER, INT64, DOUBLE, or DECIMAL before the aggregation is planned.
Cast the column to a supported numeric type in the SQL query.
Implement a custom zero-returning CombineFn (mirroring DoubleSum0: extractOutput returns 0 when accumulator empty) for the needed type.

Example fix

// before
CombineFn fn = BeamBuiltinAggregations.createSum0(Schema.FieldType.BOOLEAN); // throws

// after
CombineFn fn = BeamBuiltinAggregations.createSum0(Schema.FieldType.INT64);

Defensive patterns

Strategy: validation

Validate before calling

java.util.Set<Schema.TypeName> ok =
    java.util.Set.of(Schema.TypeName.INTEGER, Schema.TypeName.INT64, Schema.TypeName.DOUBLE, Schema.TypeName.DECIMAL);
if (!ok.contains(fieldType.getTypeName())) {
  throw new IllegalArgumentException("SUM0 unsupported for " + fieldType);
}

Type guard

boolean sum0Supported(Schema.FieldType t) {
  switch (t.getTypeName()) {
    case INTEGER: case INT64: case DOUBLE: case DECIMAL: return true;
    default: return false;
  }
}

Try / catch

try {
  CombineFn fn = BeamBuiltinAggregations.createSum0(fieldType);
} catch (UnsupportedOperationException e) {
  // substitute a custom zero-defaulting combiner
}

Prevention

Ensure SUM0-planned columns resolve to INTEGER/INT64/DOUBLE/DECIMAL.
When constructing aggregates programmatically, validate Schema.FieldType before calling the factory.
Track Beam SQL optimizer rewrites (SUM->SUM0) in query plans when debugging.

When it happens

Trigger: Calling BeamBuiltinAggregations.createSum0(fieldType) with a TypeName outside the supported numeric set (e.g. STRING, BOOLEAN, TIMESTAMP) — reached when Beam SQL plans a SUM0 aggregate (emitted for COUNT-style or null-safe SUM rewrites) over an unsupported column type.

Common situations: Optimizer rewriting SUM into SUM0 internally over a column type that was not validated; users constructing aggregation pipelines programmatically with the wrong Schema.FieldType.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/54e0874b85759995. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/transform/BeamBuiltinAggregations.java:204

   */
  static CombineFn createSum0(Schema.FieldType fieldType) {
    switch (fieldType.getTypeName()) {
      case INT32:
        return new IntegerSum0();
      case INT16:
        return new ShortSum0();
      case BYTE:
        return new ByteSum0();
      case INT64:
        return new LongSum0();
      case FLOAT:
        return new FloatSum0();
      case DOUBLE:
        return new DoubleSum0();
      case DECIMAL:
        return new BigDecimalSum0();
      default:
        throw new UnsupportedOperationException(
            String.format("[%s] is not supported in SUM0", fieldType));
    }
  }

  /** {@link CombineFn} for AVG. */
  static CombineFn createAvg(Schema.FieldType fieldType) {
    switch (fieldType.getTypeName()) {
      case INT32:
        return new IntegerAvg();
      case INT16:
        return new ShortAvg();
      case BYTE:
        return new ByteAvg();
      case INT64:
        return new LongAvg();
      case FLOAT:
        return new FloatAvg();
      case DOUBLE:

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