c# - 如何使用 Azure 函数将数据附加到 Azure blob 中的 parquet 文件

Question

我正在尝试使用 Azure 函数 c# 脚本附加到 Azure blob 中的 parquet 文件。

我已经能够使用 Parquet.net 包附加到本地创建的 parquet 文件。但是，当我尝试执行代码以附加到 Azure 中的 Parquet 文件时，我收到错误。

下面的代码适用于本地 Parquet 文件附加。

var ds = new DataSet(new DataField<int>("id"),new DataField<string>("city"));
ds.Add(1, "London");
using (Stream fileStream = File.Open(file, FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
   ParquetWriter.Write(ds, fileStream,CompressionMethod.None,null,null, true);
   Console.Write("File writing completed successfully\n");
}

但是，下面的代码不适用于 Azure parquet 文件附加

var ds = new DataSet(new DataField<int>("id"),new DataField<string>("city"));
ds.Add(1, "London");
Stream stream = new MemoryStream();
ParquetWriter.Write(ds, stream,CompressionMethod.None,null,null, false);
parquetBlob.AppendBlock(stream); //this line fails with error

我收到以下错误:

2018-07-05T05:07:14.479 [Info] Parquet file writing started
2018-07-05T05:07:14.667 [Info] Parquet file writing : successfully written to memory stream
2018-07-05T05:07:14.686 [Info] Exception  while appending to parquet file: Microsoft.WindowsAzure.Storage.StorageException: The remote server returned an error: (400) Bad Request. ---> System.Net.WebException: The remote server returned an error: (400) Bad Request.
   at System.Net.HttpWebRequest.GetResponse()
   at Microsoft.WindowsAzure.Storage.Core.Executor.Executor.ExecuteSync[T](RESTCommand`1 cmd, IRetryPolicy policy, OperationContext operationContext) in c:\Program Files (x86)\Jenkins\workspace\release_dotnet_master\Lib\ClassLibraryCommon\Core\Executor\Executor.cs:line 677
   --- End of inner exception stack trace ---
   at Microsoft.WindowsAzure.Storage.Core.Executor.Executor.ExecuteSync[T](RESTCommand`1 cmd, IRetryPolicy policy, OperationContext operationContext) in c:\Program Files (x86)\Jenkins\workspace\release_dotnet_master\Lib\ClassLibraryCommon\Core\Executor\Executor.cs:line 604
   at Microsoft.WindowsAzure.Storage.Blob.CloudAppendBlob.AppendBlock(Stream blockData, String contentMD5, AccessCondition accessCondition, BlobRequestOptions options, OperationContext operationContext) in c:\Program Files (x86)\Jenkins\workspace\release_dotnet_master\Lib\ClassLibraryCommon\Blob\CloudAppendBlob.cs:line 2145
   at Submission#0.writeParquet(String data, CloudAppendBlob parquetBlob, TraceWriter log) in D:\home\site\wwwroot\EventHubTriggerCSharp2\run.csx:line 189
   at Submission#0.WriteToBlob(String fileName, String data, TraceWriter log) in D:\home\site\wwwroot\EventHubTriggerCSharp2\run.csx:line 158
Request Information
RequestID:45299e54-001e-009d-7d1e-143e91000000
RequestDate:Thu, 05 Jul 2018 05:07:13 GMT
StatusMessage:The value for one of the HTTP headers is not in the correct format.
ErrorCode:InvalidHeaderValue

任何帮助将不胜感激。

Answer 1

@Gaurav 为我们指明了道路。

The value for one of the HTTP headers is not in the correct format.如果我们检查RequestInformation，我们会发现Content-Length为0。

在将流附加到 blob 之前，您需要先将流返回到开头。

添加stream.Position = 0之前parquetBlob.AppendBlock(stream);