apache/iceberg · error · UnsupportedOperationException

Cannot support vectorized reads for column " + desc + "…

Error message

Cannot support vectorized reads for column " + desc + " with encoding " + dataEncoding + ". Disable vectorized reads to read this table/file

What it means

The vectorized Parquet reader only implements vectorized decoding for a fixed set of encodings (PLAIN, dictionary-based, DELTA_BYTE_ARRAY, BYTE_STREAM_SPLIT, etc.). If a data page uses any other encoding, initDataReader throws UnsupportedOperationException and tells the user to disable vectorized reads. It is a capability limitation, not data corruption.

Solutions

Disable vectorized reads for the scan/table (Spark: SET spark.sql.iceberg.vectorization.enabled=false; or table property read.split.vectorization.enabled=false).
Rewrite the data files with encodings the vectorized reader supports (e.g. via Iceberg rewrite_data_files after adjusting parquet writer settings).
Upgrade Iceberg — newer versions add vectorized support for more encodings (e.g. DELTA_BINARY_PACKED).

Example fix

// before
SELECT ... FROM tbl -- vectorized read hits unsupported encoding
// after
SET spark.sql.iceberg.vectorization.enabled=false;
SELECT ... FROM tbl

Defensive patterns

Strategy: fallback

Validate before calling

// Inspect file encodings before enabling vectorized reads
// parquet-tools meta file.parquet  -> check encodings per column
// If DELTA_BINARY_PACKED or other unsupported encodings are present, disable vectorization

Try / catch

try {
  // vectorized read
} catch (UnsupportedOperationException e) {
  if (e.getMessage().contains("Cannot support vectorized reads")) {
    // retry the read with vectorization disabled
  } else throw e;
}

Prevention

Check file encodings (parquet-tools / metadata) before enabling vectorized reads
Set spark.sql.iceberg.vectorization.enabled=false for tables written by engines using unsupported encodings
Rewrite files with vectorized-supported encodings; upgrade Iceberg for newer encoding support

When it happens

Trigger: initDataReader's encoding switch hits the default branch — e.g. pages encoded with DELTA_BINARY_PACKED, RLE on non-boolean data, or other unsupported encodings read via the vectorized path.

Common situations: Files written by other engines/writers (e.g. delta-binary-packed integer columns from Spark/Parquet-mr defaults) read through Iceberg's vectorized reader.

Related errors

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/354caac0d5749d1b. Report an issue: GitHub.

Appendix: source

Thrown at arrow/src/main/java/org/apache/iceberg/arrow/vectorized/parquet/VectorizedPageIterator.java:116

        case PLAIN:
          valuesReader = new VectorizedPlainValuesReader();
          break;
        case DELTA_BINARY_PACKED:
          valuesReader = new VectorizedDeltaEncodedValuesReader();
          break;
        case DELTA_LENGTH_BYTE_ARRAY:
          valuesReader = new VectorizedDeltaLengthByteArrayValuesReader();
          break;
        case DELTA_BYTE_ARRAY:
          valuesReader = new VectorizedDeltaByteArrayValuesReader();
          break;
        case BYTE_STREAM_SPLIT:
          valuesReader =
              new VectorizedByteStreamSplitValuesReader(
                  byteStreamSplitElementSize(desc.getPrimitiveType()));
          break;
        default:
          throw new UnsupportedOperationException(
              "Cannot support vectorized reads for column "
                  + desc
                  + " with "
                  + "encoding "
                  + dataEncoding
                  + ". Disable vectorized reads to read this table/file");
      }
      try {
        valuesReader.initFromPage(valueCount, in);
      } catch (IOException e) {
        throw new ParquetDecodingException(
            "could not read page " + valueCount + " in col " + desc, e);
      }
      dictionaryDecodeMode = DictionaryDecodeMode.NONE;
    }
    if (CorruptDeltaByteArrays.requiresSequentialReads(writerVersion, dataEncoding)
        && previousReader instanceof RequiresPreviousReader) {
      // previous reader can only be set if reading sequentially

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