Locate a recovery point for a point-in-time recovery

In the context of designing and implementing native applications using Microsoft Azure Cosmos DB, you may need to locate a recovery point for a point-in-time recovery. This allows you to recover your data to an earlier point in time, providing protection against accidental deletion or modification of data. Here are the steps to follow:

1. Understand Point-in-Time Recovery

Azure Cosmos DB offers a feature called Point-in-Time Recovery (PITR) that enables you to recover data to a specific point in time. PITR provides an added layer of data protection for your applications.

2. Enable Point-in-Time Recovery

To enable PITR for your Azure Cosmos DB account:

• During the creation or update process, configure PITR settings.
• Choose one of these options: Azure portal, Azure CLI, Azure PowerShell, or Azure Resource Manager templates.
• Refer to the official Azure documentation for detailed instructions on enabling PITR.

3. Determine Recovery Point Options

Once PITR is enabled, you can locate recovery points for a specific container within your Azure Cosmos DB account. Recovery points are stored automatically based on your chosen time granularity (e.g., 5 minutes). The two key attributes to consider when identifying recovery points are LSN (Log Sequence Number) and timestamp.

4. Retrieve the LSN Range

To fetch the LSN range applicable to your container, use the Azure Cosmos DB SDK or Azure portal programmatically. This range is crucial for performing point-in-time recovery within the desired scope.

Here’s an example of using the Azure Cosmos DB SDK for .NET:

csharp
using Microsoft.Azure.Cosmos;

public async Task GetLSNRange(string databaseId, string containerId)
{
CosmosClient client = new CosmosClient(“connection-string”);
Container container = client.GetContainer(databaseId, containerId);
FeedResponse locations = await client.ReadDatabaseAccountAsync();

foreach (DatabaseAccountLocation location in locations)
{
if (location.Name == “YourPreferredRegion”)
{
return await container.GetContainerLSNRangeAsync(location.Endpoint);
}
}

return null;
}

Remember to replace `”connection-string”`, `”databaseId”`, `”containerId”`, and `”YourPreferredRegion”` with appropriate values.

5. Determine the Target LSN

Identify the LSN within the range for the desired point-in-time recovery. Each recovery point has an associated LSN. Retrieve the timestamp associated with the desired point in time and compare it against the LSN range obtained in the previous step.

Here’s an example method to determine the target LSN:

csharp
public long GetTargetLSN(LSNRange lsnRange, DateTimeOffset targetTimestamp)
{
foreach (PointInTimeRecoveryRange recoveryRange in lsnRange.Ranges)
{
if (recoveryRange.StartTime <= targetTimestamp && recoveryRange.EndTime >= targetTimestamp)
{
return recoveryRange.StartLSN;
}
}

return -1; // Target timestamp not found within recovery ranges
}

Once again, don’t forget to replace the parameters with relevant values.

6. Initiate Point-in-Time Recovery

Having identified the target LSN, you can initiate the point-in-time recovery process using the Azure Cosmos DB SDK. Send a request to the server specifying the target container, LSN, and desired recovery location.

Here’s an example of initiating the recovery process:

csharp
public async Task InitiatePointInTimeRecovery(string databaseId, string containerId, long targetLSN, string region)
{
CosmosClient client = new CosmosClient(“connection-string”);
Container container = client.GetContainer(databaseId, containerId);
PointInTimeRecoveryPoint recoveryPoint = await container.CreatePointInTimeRecoveryAsync(targetLSN, region);
Console.WriteLine($”Recovery initiated. Recovery point: {recoveryPoint.Id}”);
}

Replace the parameters accordingly.

7. Verify and Access Recovered Data

After initiating the recovery process, verify the success of the operation. You can then access the recovered data using standard methods provided by the Cosmos DB SDK, such as queries, reads, or writes.

Remember to handle exceptions and any edge cases, such as when a recovery point is not found within the specified LSN range.

Congratulations! You have learned how to locate a recovery point for point-in-time recovery in Azure Cosmos DB when designing and implementing native applications. Reference the Azure documentation for further information and explore more features offered by Azure Cosmos DB to enhance your application’s resilience and data protection.