Azure 存储表逐行键删除

Question

I am trying to delete row from azure storage filter by only rowkey value. But I dont see any overload for delete operation where we can filter with only rowkey. Is there any alternative option to delete row from azure storage table for records with specific rowkey?

RemoveEntityByRowKey('123456');
public static void RemoveEntityByRowKey(string myRowKey)
        {
            try
            {
                CloudTable table = _tableClient.GetTableReference("MyAzureTable"); 
                       TableOperation delteOperation = TableOperation.Delete(myRowKey);
                table.Execute(delteOperation);
            }
            catch (Exception ex)
            {
                LogError.LogErrorToAzure(ex);
                throw;
            }
        }

Answer 1

In order to delete an entity, you would need both PartitionKey and RowKey ( Delete Entity REST API ). So what you would need to do is first fetch the entity with matching RowKey . Once you have fetched this entity, you should be able to call TableOperation.Delete as mentioned in the answers.

However, fetching entity by RowKey is not recommended because it will do a Full Table Scan . It may not be a problem if your table size is small but would be an issue where your table contains large number of entities. Furthermore, a RowKey is unique in a Partition ie in a table there can be only one entity with a PartitionKey / RowKey combination. In other words, you can potentially have entities with same RowKey in different Partitions . So when you fetch entities by RowKey only, you may get more than one entity back. You need to ensure that you're deleting correct entity.

Answer 2

If you know the PartitionKey as well as the RowKey, you don't need to retrieve the entire entity to delete it. You could adapt your code as follows:

public static void RemoveEntityByRowKey(string myRowKey)
{
    try
    {
        var entity = new YourEntity 
        {
            PartitionKey = "partition",
            RowKey = myRowKey,
            ETag = "*"
        }

        CloudTable table = _tableClient.GetTableReference("MyAzureTable"); 
        TableOperation delteOperation = TableOperation.Delete(entity);
        table.Execute(delteOperation);
    }
    catch (Exception ex)
    {
        LogError.LogErrorToAzure(ex);
        throw;
    }
}    

Answer 3

If you're targeting .NET Core, you'll need to use the ExecuteQuerySegmentedAsync method to execute the filter condition query. ExecuteQuery is deprecated.

var cloudTableClient = _cloudStorageAccount.CreateCloudTableClient();
var myTable = cloudTableClient.GetTableReference("MyTable");
var query = new TableQuery<MyEntity>().Where(TableQuery.GenerateFilterCondition("RowKey", QueryComparisons.Equal, "myRowKey"));
var segment = await myTable.ExecuteQuerySegmentedAsync(query, null);
var myEntities = segment.Results;

Answer 4

By row do you mean a record?

TableOperation.Delete accepts a Table Entity. See here: https://msdn.microsoft.com/en-us/library/microsoft.windowsazure.storage.table.tableoperation.delete.aspx

In order to delete that entity, you must first retrieve it by specifying its Partition key and/or Row key.

Look into TableQuery class here https://msdn.microsoft.com/en-us/library/microsoft.windowsazure.storage.table.tablequery_methods.aspx

Once you retrieve it, pass it to Delete method.

Answer 5

There is no method

TableOperation.Delete(String rowKey) ,

only method

public static TableOperation delete(final TableEntity entity)

in TableOperation. For details, see Get started with Azure Table storage using .NET

Answer 6

With reference to Franks pointers, I am posting answer so that it would be useful to others who face the similar issue.

RemoveEntityByRowKey('123456');
public static void RemoveEntityByRowKey(string myRowKey)
        {
            try
            {
                CloudTable table = _tableClient.GetTableReference("MyAzureTable"); 

   TableQuery<myEntity> query = new TableQuery<myEntity>()
                   .Where(TableQuery.GenerateFilterCondition("RowKey", QueryComparisons.Equal, myRowKey));

                foreach (var item in table.ExecuteQuery(query))
                {
                    var oper = TableOperation.Delete(item);
                    table.Execute(oper);                    
                } 
            }
            catch (Exception ex)
            {
                LogErrorToAzure(ex);
                throw;
            }
        }

Answer 7

mpl is my table row entity and is required to delete the record from the db. I have added this answer to show an async (with result check)

           if (result)
            {
                //delete the lead from the storage table
                TableOperation delRow = TableOperation.Delete(mpl);
                TableResult tr = await table.ExecuteAsync(delRow);
                if (((int)tr.HttpStatusCode) < 400)
                    log.LogInformation($"Table Record: {mpl.RowKey} deleted");
                else
                    log.LogError($"Table Record: {mpl.RowKey} NOT deleted");

            }

Answer 8

The Windows.Azure.Storage namespace is now deprecated in favour of the Azure.Data.Tables namespace. As such the TableOperation.Delete method is also deprecated . You should now use a TableClient and it's DeleteEntity method:

TableClient tableClient = new TableClient(connectionString, Table);
tableClient.DeleteEntity(PartitionKey, RowKey);

There is also the async version DeleteEntityAsync if you wish too.