在Azure存储中删除批处理操作

Question

我一直在尝试为Azure存储实体的删除操作实现DAO方法。使用TableOperation删除可以。

TableOperation deleteEntity = TableOperation.delete(entity); 

但是，当我尝试使用批处理操作，它不被支持。

任何建议来解决这个问题是高度赞赏。

Answer 1

但是，当我尝试使用批量操作，它不支持。

我认为你可以将你的项目按分区键进行分组，然后执行TableBatchOperation。

在这里，我写了通过C＃语言的一个辅助类为实现这一目的，你可以参考一下吧：

public class TableBatchHelper<T> where T : ITableEntity 
{ 
    const int batchMaxSize = 100; 

    public static IEnumerable<TableBatchOperation> GetBatchesForDelete(IEnumerable<T> items) 
    { 
     var list = new List<TableBatchOperation>(); 
     var partitionGroups = items.GroupBy(arg => arg.PartitionKey).ToArray(); 
     foreach (var group in partitionGroups) 
     { 
      T[] groupList = group.ToArray(); 
      int offSet = batchMaxSize; 
      T[] entities = groupList.Take(offSet).ToArray(); 
      while (entities.Any()) 
      { 
       var tableBatchOperation = new TableBatchOperation(); 
       foreach (var entity in entities) 
       { 
        tableBatchOperation.Add(TableOperation.Delete(entity)); 
       } 
       list.Add(tableBatchOperation); 
       entities = groupList.Skip(offSet).Take(batchMaxSize).ToArray(); 
       offSet += batchMaxSize; 
      } 
     } 
     return list; 
    } 

    public static async Task BatchDeleteAsync(CloudTable table, IEnumerable<T> items) 
    { 
     var batches = GetBatchesForDelete(items); 
     await Task.WhenAll(batches.Select(table.ExecuteBatchAsync)); 
    } 
} 

然后，你可能在你执行批处理删除如下：

await TableBatchHelper<ClassName>.BatchDeleteAsync(cloudTable,items); 

或

var batches = TableBatchHelper<ClassName>.GetBatchesForDelete(entities); 
Parallel.ForEach(batches, new ParallelOptions() 
{ 
    MaxDegreeOfParallelism = 5 
}, (batchOperation) => 
    { 
     try 
     { 
      table.ExecuteBatch(batchOperation); 
      Console.WriteLine("Writing {0} records", batchOperation.Count); 
     } 
     catch (Exception ex) 
     { 
      Console.WriteLine("ExecuteBatch throw a exception:" + ex.Message); 
     } 
    }); 

Answer 2

public void deleteLocationsForDevice(String id) { 
    logger.info("Going to delete location data for Device [{}]", id); 

    // Create a filter condition where the partition key is deviceId. 
    String partitionFilter = TableQuery.generateFilterCondition(
      PARTITION_KEY, 
      TableQuery.QueryComparisons.EQUAL, 
      id); 

    // Specify a partition query, using partition key filter. 
    TableQuery<AzureLocationData> partitionQuery = 
      TableQuery.from(AzureLocationData.class) 
        .where(partitionFilter); 



    if (partitionQuery != null) { 
     for (AzureLocationData entity : cloudTable.execute(partitionQuery)) { 

      TableOperation deleteEntity = TableOperation.delete(entity); 
      try { 
       cloudTable.execute(deleteEntity); 
       logger.info("Successfully deleted location records with : " + entity.getPartitionKey()); 
      } catch (StorageException e) { 
       e.printStackTrace(); 
      } 

     } 

    } else { 
     logger.debug("No records to delete!"); 
    } 

    // throw new UnsupportedOperationException("AzureIotLocationDataDao Delete Operation not supported"); 
} 

Answer 3

不，这是没有使用块操作的代码。以下是包含块操作的代码。对不起，没有提及

TableBatchOperation batchOperation = new TableBatchOperation(); 
    List<TableBatchOperation> list = new ArrayList<>(); 

    if (partitionQuery != null) { 
     for (AzureLocationData entity : cloudTable.execute(partitionQuery)) { 

      batchOperation.add(TableOperation.delete(entity)); 
      list.add(batchOperation); //exception thrown line 
     } 
     try { 
      cloudTable.execute((TableOperation) batchOperation); 
     } catch (StorageException e) { 
      e.printStackTrace(); 
      } 
      }