apache/druid · error · UnsupportedOperationException

Table decoding not supported for

Error message

Table decoding not supported for %s

What it means

VSizeLongSerde long-column encodings that do not implement table-based decoding throw this UnsupportedOperationException from the default ColumnarLongsSupplier.getLongMulti/getTable default method. It means the requested vectorized 'lookup and replace' decode path is unavailable for the concrete LongValueEncoding in use. It is a 'this encoding doesn't support this operation' guard, not data corruption.

Solutions

1. Verify the segment's long column encoding; re-ingest or re-index the segment with a current Druid version so the column is written with table-decoding-capable encoding
2. Fall back to the non-table decode path: catch UOE and re-run the query with vectorization disabled (set druid.query.vectorize=false or use non-vectorized selectors)
3. Upgrade Druid on the node serving the segment so the encoding implements getTable

Example fix

// before
encoding.getTable(out, outPosition, startIndex, length, table);
// after
try {
  encoding.getTable(out, outPosition, startIndex, length, table);
} catch (UnsupportedOperationException e) {
  encoding.fill(out, outPosition, startIndex, length); // non-table fallback
}

// Java: check if the encoding supports table decoding before use
if (encoding.getClass().getSimpleName().equals("LongEncodingReader")) { /* fall back */ }

boolean supportsTableDecode(ColumnarLongsSerializer encoding) {
  try { encoding.getClass().getMethod("getTable", long[].class, int.class, int.class, int.class, long[].class); return true; }
  catch (NoSuchMethodException e) { return false; }
}

try {
  encoding.getTable(out, outPosition, startIndex, length, table);
} catch (UnsupportedOperationException e) {
  // fall back to non-table decode
  encoding.fill(out, outPosition, startIndex, length);
}

When it happens

Trigger: Calling getTable(long[], int, int, int, long[]) (or vectorized table-based decoding via a LongValueEncoding that only overrides fill/forEach) on a column written with an encoding that lacks table decode support, e.g. a VSizeLongSerde v1-encoded column without table-decoding support.

Common situations: Running vectorized group-by/search queries over older segments whose long column encoding predates table decoding support; mixing Druid versions where a broker routes vectorized work to a historical with older segment files.

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.

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AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/113eed40ab12f135. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/segment/data/VSizeLongSerde.java:464

      for (int i = 0; i < length; i++) {
        int index = indexes[outPosition + i] - indexOffset;
        if (index >= limit) {
          return i;
        }

        out[outPosition + i] = base + get(index);
      }

      return length;
    }

    /**
     * Unpack a contiguous vector of long values at the specified start index of length and lookup and replace stored
     * values based on their index in the supplied value lookup 'table'
     */
    default void getTable(long[] out, int outPosition, int startIndex, int length, long[] table)
    {
      throw new UOE("Table decoding not supported for %s", this.getClass().getSimpleName());
    }

    /**
     * Unpack a contiguous vector of long values at the specified indexes and lookup and replace stored values based on
     * their index in the supplied value lookup 'table'
     */
    default int getTable(
        long[] out,
        int outPosition,
        int[] indexes,
        int length,
        int indexOffset,
        int limit,
        long[] table
    )
    {
      for (int i = 0; i < length; i++) {
        int index = indexes[outPosition + i] - indexOffset;

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