Deleting Entities in Azure Storage Tables

This document explains how to delete entities from an Azure Storage table. Deleting entities is a common operation when managing your data. You can delete single entities or batches of entities efficiently.

Methods for Deleting Entities

Azure Storage Tables provide several ways to delete entities:

• Delete Entity: Removes a single entity from a table.
• Delete Entity Batch: Removes multiple entities in a single batch operation. This is more efficient than individual deletes.

Deleting a Single Entity

To delete a single entity, you need to provide its PartitionKey and RowKey. These two properties uniquely identify an entity within a table.

Using the Azure SDK (C# Example)

Here's an example demonstrating how to delete a single entity using the Azure SDK for .NET:

using Azure.Data.Tables;
using System;
using System.Threading.Tasks;

public class TableEntityDeleter
{
    public static async Task DeleteSingleEntityAsync(string connectionString, string tableName, string partitionKey, string rowKey)
    {
        var serviceClient = new TableServiceClient(connectionString);
        var tableClient = serviceClient.GetTableClient(tableName);

        try
        {
            await tableClient.DeleteEntityAsync(partitionKey, rowKey);
            Console.WriteLine($"Entity with PartitionKey '{partitionKey}' and RowKey '{rowKey}' deleted successfully.");
        }
        catch (Azure.RequestFailedException ex)
        {
            Console.WriteLine($"Error deleting entity: {ex.Message}");
        }
    }

    // Example usage:
    // public static async Task Main(string[] args)
    // {
    //     string connString = "YOUR_AZURE_STORAGE_CONNECTION_STRING";
    //     string table = "MyTable";
    //     string pk = "Partition1";
    //     string rk = "Row1";
    //
    //     await DeleteSingleEntityAsync(connString, table, pk, rk);
    // }
}

Using the Azure CLI

You can also delete entities using the Azure Command-Line Interface. This typically involves retrieving the entity's ETag and then issuing a DELETE command.

# First, get the ETag of the entity you want to delete
az storage table entity query --table-name MyTable --account-name mystorageaccount --account-key YOUR_ACCOUNT_KEY --filter "PartitionKey eq 'Partition1' and RowKey eq 'Row1'" --select RowKey,ETag --output json

# Then, use the ETag to delete the entity
az storage table entity delete --table-name MyTable --account-name mystorageaccount --account-key YOUR_ACCOUNT_KEY --partition-key Partition1 --row-key Row1 --etag "YOUR_ENTITY_ETAG"

Deleting Multiple Entities in a Batch

Deleting multiple entities individually can be inefficient due to network latency for each request. Azure Storage Tables support batch operations, allowing you to delete several entities in a single HTTP request.

Important: A batch operation can only contain entities from the same partition. If you need to delete entities from different partitions, you must send separate batch requests.

Using the Azure SDK (C# Example)

Here's how to perform a batch delete operation for entities within the same partition:

using Azure.Data.Tables;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;

public class TableBatchDeleter
{
    public static async Task DeleteBatchEntitiesAsync(string connectionString, string tableName, string partitionKey, List<string> rowKeys)
    {
        var serviceClient = new TableServiceClient(connectionString);
        var tableClient = serviceClient.GetTableClient(tableName);

        var batch = new TableBatchClient(tableClient);
        foreach (var rowKey in rowKeys)
        {
            batch.DeleteEntity(partitionKey, rowKey);
        }

        try
        {
            await batch.SubmitBatchAsync();
            Console.WriteLine($"Batch delete operation for {rowKeys.Count} entities in partition '{partitionKey}' submitted successfully.");
        }
        catch (Azure.RequestFailedException ex)
        {
            Console.WriteLine($"Error during batch delete: {ex.Message}");
        }
    }

    // Example usage:
    // public static async Task Main(string[] args)
    // {
    //     string connString = "YOUR_AZURE_STORAGE_CONNECTION_STRING";
    //     string table = "MyTable";
    //     string pk = "Partition1";
    //     var rksToDelete = new List<string> { "Row1", "Row2", "Row3" };
    //
    //     await DeleteBatchEntitiesAsync(connString, table, pk, rksToDelete);
    // }
}

Considerations for Deletion

• PartitionKey and RowKey: Always have the correct PartitionKey and RowKey to identify the entity for deletion.
• ETag: When using the REST API or certain SDK methods, the ETag is crucial for optimistic concurrency control. If the ETag doesn't match, the delete operation will fail, preventing accidental overwrites or deletions. The .NET SDK often handles this automatically.
• Batch Size: Azure Storage Tables have limits on the number of operations per batch (e.g., 100 operations). For very large-scale deletions, you may need to implement logic to submit multiple batches.
• Error Handling: Always implement robust error handling to manage potential issues like entities not being found or network errors.

Deleting All Entities in a Table

There is no direct API call to delete all entities in a table in a single operation. The common approaches are:

1. Query and Batch Delete: Query for entities in batches (e.g., 100 at a time) and then submit batch delete operations for each retrieved batch.
2. Delete and Recreate Table: In some scenarios, it might be simpler and more efficient to delete the entire table and then recreate it, especially if you don't need to preserve table metadata.

For detailed information on table management, refer to the Azure Storage Tables documentation.