apache/druid · error · UnsupportedOperationException

Directory decompression not supported for %s

Error message

Directory decompression not supported for %s

What it means

The CompressionFormat.decompressDirectory default method throws UnsupportedOperationException because not every format can decompress a whole directory stream; only formats with directory support (gzip/tgz, zip) override it. Calling it on a stream-compression-only format such as LZ4 or ZSTD throws this error. Use the format-specific decompression helpers instead.

Source

Thrown at processing/src/main/java/org/apache/druid/utils/CompressionUtils.java:195

     */
    public long compressDirectory(File directory, OutputStream out) throws IOException
    {
      throw new UnsupportedOperationException("Directory compression not supported for " + this.name());
    }

    /**
     * Decompresses a directory from the input stream. Default implementation throws UnsupportedOperationException.
     * Override this method for formats that support directory decompression.
     *
     * @param in The input stream containing compressed data
     * @param outDir The output directory to extract files to
     * @return A FileCopyResult containing information about extracted files
     * @throws IOException if an I/O error occurs
     * @throws UnsupportedOperationException if the format doesn't support directory decompression
     */
    public FileUtils.FileCopyResult decompressDirectory(InputStream in, File outDir) throws IOException
    {
      throw new UnsupportedOperationException("Directory decompression not supported for " + this.name());
    }
  }

  public static final int COMPRESSED_TEXT_WEIGHT_FACTOR = 4;
  private static final Logger log = new Logger(CompressionUtils.class);
  private static final int DEFAULT_RETRY_COUNT = 3;
  private static final int GZIP_BUFFER_SIZE = 8192; // Default is 512

  /**
   * Zip the contents of directory into the file indicated by outputZipFile. Sub directories are skipped
   *
   * @param directory     The directory whose contents should be added to the zip in the output stream.
   * @param outputZipFile The output file to write the zipped data to
   * @param fsync         True if the output file should be fsynced to disk
   *
   * @return The number of bytes (uncompressed) read from the input directory.
   *
   * @throws IOException

View on GitHub (pinned to 9b90983fd2)

Solutions

1. Use the format-specific decompression path, e.g. CompressionUtils.decompress with a LZ4 InputStream factory, for stream-only formats
2. Restrict directory decompression to GZIP/ZIP formats and validate the configured format beforehand
3. Catch UnsupportedOperationException and fall back to stream decompression into the target directory
4. Check the CompressionFormat implementation for your Druid version to confirm directory support

Example fix

// before
format.decompressDirectory(in, outDir); // throws for LZ4/ZSTD
// after
if (format == CompressionUtils.CompressionFormat.LZ4) {
  CompressionUtils.decompress(in, outDir, CompressionUtils.LZ4_STREAM_FACTORY);
} else {
  format.decompressDirectory(in, outDir);
}

try {
  format.decompressDirectory(in, outDir);
} catch (UnsupportedOperationException e) {
  CompressionUtils.decompress(in, outDir, format-specificFactory);
}

When it happens

Trigger: Calling decompressDirectory on a CompressionFormat like LZ4 or ZSTD, or generically dispatching decompression over formats without checking which override decompressDirectory.

Common situations: Restore/load jobs that decompress whatever format a config names; archives written by a stream compressor being fed to decompressDirectory; version drift where a format lacks the directory override.

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

• Directory compression not supported for %s
• NONE compression strategy shouldn't use any decompressor
• NONE compression strategy shouldn't use any compressor
• Reverse lookup not allowed.
• Serialization not supported here

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/3a73e2495e4b7a59. Report an issue: GitHub.