apache/iceberg · error · UnsupportedOperationException

ORC cannot read default value for field

Error message

ORC cannot read default value for field %s (%s): %s

What it means

During buildOrcProjection, an Iceberg field missing from the ORC file is handled by writing a column filled with the field's default value. ORC's VectorizedRowBatch machinery cannot materialize Iceberg initial-default values, so if the field declares a non-null initialDefault an UnsupportedOperationException with the field name, type, and default is thrown. The error occurs at read planning time, not mid-scan of data.

Solutions

1. Add the column without an initialDefault (or use write-default only), then rewrite data files so old files contain the column.
2. Rewrite old ORC data files (e.g. rewrite_data_files / Spark rewrite) so the added column physically exists and no default back-fill is needed.
3. Drop the requirement/default for the field, or use a file format whose reader supports initial-default materialization (Parquet).

Example fix

// before
ALTER TABLE t ADD COLUMN status STRING NOT NULL WITH default 'new';
// old ORC files: UnsupportedOperationException

// after
ALTER TABLE t ADD COLUMN status STRING; -- nullable, no initialDefault
-- then backfill data via rewrite/update instead of relying on reader-side defaults

// detect problematic evolved fields before scanning
Types.NestedField f = schema.findField(fieldId);
if (f != null && f.isOptional() == false && f.initialDefault() != null && !fileContainsColumn) {
  throw new UnsupportedOperationException("Rewrite files before scan: " + f.name());
}

try {
  CloseableIterable<Record> rows = read.build();
} catch (UnsupportedOperationException e) {
  if (e.getMessage().startsWith("ORC cannot read default value")) {
    // trigger rewrite_data_files or fall back to Parquet path
  }
}

When it happens

Trigger: Reading (projection building for) an ORC data file whose schema predates an Iceberg schema evolution that ADDED a required field with an initialDefault; the missing field must be back-filled and its initialDefault() is non-null.

Common situations: Schema evolution: ALTER TABLE ADD COLUMN with a default value on an ORC table, then scanning old ORC files written before the column existed; ORC format does not support default-value materialization the way Parquet readers do.

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

• Batch reading is not supported in non-vectorized reader
• Can't get Stripe's length from the file writer with path
• Failed to get ORC rows for file
• Failed to get statistics from writer
• Failed to get stripe information from writer for

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/0be69cf3358459fa. Report an issue: GitHub.

Appendix: source

Thrown at orc/src/main/java/org/apache/iceberg/orc/ORCSchemaUtil.java:408

            Preconditions.checkArgument(
                isSameType(originalType, type),
                "Can not promote %s type to %s",
                originalType.getCategory(),
                type.typeId().name());
            orcType = originalType.clone();
          }
        } else {
          Types.NestedField field = root.findField(fieldId);
          if (isRequired) {
            Preconditions.checkArgument(
                field.initialDefault() != null,
                "Missing required field: %s (%s)",
                root.findColumnName(fieldId),
                type);
          }

          if (field.initialDefault() != null) {
            throw new UnsupportedOperationException(
                String.format(
                    "ORC cannot read default value for field %s (%s): %s",
                    root.findColumnName(fieldId), type, field.initialDefault()));
          }

          orcType = convert(fieldId, type, false);
        }
    }

    if (orcType != null) {
      orcType.setAttribute(ICEBERG_ID_ATTRIBUTE, fieldId.toString());
    }

    return orcType;
  }

  private static Map<Integer, OrcField> icebergToOrcMapping(String name, TypeDescription orcType) {
    Map<Integer, OrcField> icebergToOrc = Maps.newHashMap();

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