Revert data to a previous state

One of the critical aspects of managing data in a cloud environment is the process of reverting data to a previous state. This aspect plays a key role in making sure that your data is always reliable, safe, and secure, and is an important topic for the DP-203 Data Engineering on Microsoft Azure exam.

The ability to revert data to a previous state is a safety net that allows users to recover from both accidental changes and data corruption incidents. It’s one of the most effective techniques to ensure data durability and integrity. In Microsoft Azure, we have numerous tools at our disposal that can assist in reverting data to a previous state, with Azure Backup and Azure Storage Service being the primary methods.

Azure Backup

Azure Backup is a simple and reliable data backup solution for protecting your data. It provides multiple backup copies across diverse regions, ensuring the high availability and reliability of your data. Azure Backup could be your lifeline in situations where your data has accidentally changed, or damaged and you need to revert it to its previous state.

An example of Azure Backup usage:

1. Creating a backup: To create a backup, navigate to the Recovery Services vaults section in the Azure portal → Add. You’d be required to enter details like the name of the vault, the resource group, and region. After the vault is created, you can select Backup from the vault dashboard, and choose where the data you want to backup is, and the type of backup service you want to use.
2. Restoring the backup: To restore a backup, you need to go to the Recovery Services vault containing the backup. Select the item from the backup items list, then select the appropriate restore point, and opt for ‘Restore’.

Azure Storage Service

On the other hand, Azure Storage Service offers native data protection through soft delete, snapshots, and other related offerings. It provides features that can be handy especially in situations involving huge amounts of data.

• Azure Blob storage: Azure Blob storage provides features like Soft Delete, Snapshot, and Versioning, which allow you to keep copies of your data at different points in time, and revert data changes.

1. Soft Delete allows you to recover blobs that are deleted or versioned blobs within the retention period. Turning on soft delete is simple. In the Azure portal, go to your storage account → Blob service → Data protection → Enable soft delete.
2. Snapshots are read-only versions of a blob that are taken at a given moment in time. You can take a snapshot of a blob using the Azure portal or Azure CLI. Here is how you can do it through Azure CLI:

az storage blob snapshot --name MyBlob --container-name MyContainer --account-name MyStorageAccount --account-key MyStorageAccountKey

The above command creates a snapshot of the blob named MyBlob in the container named MyContainer. The new snapshot can be used to revert the blob to its state at the moment the snapshot was taken, as needed.

3. Versioning keeps previous versions of an object in case you want to revert to an older version. You can turn on versioning through the Azure portal by going to your storage account → Blob service → Data protection → Versioning.

By learning the concept of these Azure backup and Azure storage service features, you are one step closer to getting the DP-203 certification. The ability to quickly recover data and revert data changes is a powerful tool in your data engineer’s arsenal, and Azure provides numerous ways to ensure the safety and integrity of your data.

Practice Test

True or False: In Azure Synapse Analytics, you can use point-in-time restore to revert data to a previous state.

• True
• False

Answer: True

Explanation: Azure Synapse Analytics supports point-in-time restore, allowing you to revert your data back to a specific moment in the past.

Reverting a database to a previous state in Azure Database services requires the use of Full recovery model. Is this statement true or false?

• True
• False

Answer: True

Explanation: The Full Recovery model is required in Azure Database services for point-in-time restores, allowing you to recover your data back to any specific point.

Which of the following services in Azure supports reverting data to a previous state?

• A) Azure Blob Storage
• B) Azure Data Lake Storage
• C) Azure Cosmos DB
• D) Azure Synapse Analytics

Answer: A, C, D

Explanation: Azure Blob Storage, Azure Cosmos DB, and Azure Synapse Analytics all support data restoration to a previous state. Azure Data Lake Storage does not directly support this feature.

True or False: Azure always perform automatic backups for all databases for reverting data to a previous state.

• True
• False

Answer: False

Explanation: Azure automatically performs backups for some services like Azure SQL Database, Azure Synapse Analytics, and Azure Cosmos DB, but not for all databases. It might depend on the service tier and configuration.

The Azure Data Factory does not support reverting data to a previous state. Is this statement true or false?

• True
• False

Answer: True

Explanation: Azure Data Factory is an ETL and data integration service, it doesn’t directly support data restoration or reverting data to a previous state.

Which Azure service provides the capacity to revert data to a previous point in time, down to the second, for up to 35 days?

• A) Azure Blob Storage
• B) Azure Cosmos DB
• C) Azure SQL Database
• D) Azure Data Lake Storage

Answer: C. Azure SQL Database

Explanation: Azure SQL Database supports point-in-time restore, allowing you to recover your data back to any specific point down to the second, for up to 35 days.

True or False: In Azure, Data is always restored to the same location when reverting to a previous state.

• True
• False

Answer: False

Explanation: The restore operation creates a new resource, data is not restored to the same location but to a new database.

Which Azure service includes a ‘soft delete’ feature, helping to protect your data against inadvertent deletion?

• A) Azure Blob Storage
• B) Azure Cosmos DB
• C) Azure SQL Database
• D) Azure Data Lake Storage

Answer: A. Azure Blob Storage

Explanation: ‘Soft delete’ is a data protection feature of Azure Blob Storage, where deleting a blob merely marks it for deletion, but doesn’t immediately remove it.

True or False: Azure Backup service allows to revert data to a previous state.

• True
• False

Answer: True

Explanation: Azure Backup service allows the restoration of data to a previous state. It is designed for backing up and restoring cloud and on-premises workloads.

Can you perform point-in-time restore of an Azure SQL database to a new database within the same server?

• A) Yes
• B) No

Answer: A. Yes

Explanation: Azure SQL Database supports point-in-time restore, allowing you to recover your data back to any specific point in time within the last 35 days and restore it to a new database.

Interview Questions

What Azure service would be most appropriate for reverting data to a previous state?

Azure Backup service is the most appropriate for reverting data to a previous state.

What would you use to perform a Point-In-Time Restore of an Azure SQL Database to a previous state?

Azure portal, PowerShell, or T-SQL can be used to perform a Point-In-Time Restore of an Azure SQL Database to a previous state.

True or False: Azure Data Lake Store supports snapshot to revert data to a previous state?

False. Azure Data Lake Store does not support snapshot capabilities.

In Azure, how long are automatic backups of Azure SQL databases retained?

Automatic backups of Azure SQL databases are retained for up to 35 days.

Can the retention period of automatic backups in Azure SQL databases be extended beyond 35 days?

Yes, by configuring the Long-term backup retention (LTR) policy, the retention period can be extended up to 10 years.

What is Azure Blob Versioning?

Azure Blob Versioning is a feature that automatically keeps previous versions of an object in Azure Blob Storage to provide data protection and to allow for the retrieval of any version.

Can Azure Blob Versioning be enabled or disabled at any time?

Yes, Azure Blob Versioning can be enabled or disabled at any time. However, disabling it does not delete existing versions.

How can you access a previous version of a blob in Azure Blob storage?

Previous versions of a blob can be accessed through the Azure portal, PowerShell, CLI or SDKs by referencing the version id of the blob.

Does Azure Cosmos DB support the option to revert data to a previous version?

No, Azure Cosmos DB does not natively support reverting data to a previous version.

What tool can you use to manage backups of on-premises SQL Server databases in Azure?

Azure Backup Server can be used to manage backups of on-premises SQL Server databases in Azure.

What is the command in Azure PowerShell to restore an Azure SQL Database to a point in time?

The command is

Restore-AzSqlDatabase

with

-FromPointInTimeBackup

option.

What is the purpose of the “Soft Delete” option in Azure Backup service?

The "Soft Delete" option in Azure Backup service protects backup data from accidental or malicious deletion. Even after deletion, the backup data is retained for 14 additional days.

On Azure, can you restore deleted blob data?

Yes, Azure Blob Storage supports soft delete feature where deleted blobs can be restored within the retention period.

What consistency model does Azure Blob Versioning provide?

Azure Blob Versioning provides strong consistency model.

Does Azure Data Factory support data versioning and reversion to a previous state?

No, Azure Data Factory does not support data versioning or reversion to a previous state. Data Factory is more about data movement rather than storage and restoration.