Listing 2: The Decompression Function

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.IO;
using System.IO.Compression;

public partial class UserDefinedFunctions
{
  [Microsoft.SqlServer.Server.SqlFunction(IsDeterministic = true, 
    DataAccess = DataAccessKind.None)]
  public static SqlBytes fn_decompress(SqlBytes compressedBlob)
    {
      if (compressedBlob.IsNull)
        return compressedBlob;
      // Prepare to read the data from the compressed stream.
      DeflateStream decompressor = new DeflateStream(compressedBlob.Stream,
        CompressionMode.Decompress, true);
// BEGIN CALLOUT A
      // Initialize the variables.
      int bytesRead = 1;
      int chunkSize = 10000;
      byte[] chunk = new byte[chunkSize];
      // Prepare the destination stream to hold the decompressed data.
      MemoryStream decompressedData = new MemoryStream();
      try
      {
        // Read from the compressed stream.
        while ((bytesRead = decompressor.Read(chunk, 0, chunkSize)) > 0)
        {
          // Write the decompressed data.
          decompressedData.Write(chunk, 0, bytesRead); 
        }
      }
// END CALLOUT A
      catch (Exception)
      {
        throw; 
      }
      finally
      {
        // Clean up.
        decompressor.Close();
        decompressor = null;
      }
      // Return a decompressed BLOB.
      return new SqlBytes(decompressedData);
    }
};