Azure SQL Database Interview Questions and Answers

1. What is Azure SQL Database?

   • Answer: Azure SQL Database is a fully managed relational database service in the Microsoft cloud. It's based on the Microsoft SQL Server database engine and offers various service tiers to meet different performance and scalability needs.

2. What are the different service tiers in Azure SQL Database?

   • Answer: Azure SQL Database offers several service tiers including General Purpose, Business Critical, Hyperscale, and Managed Instance. Each tier provides different levels of performance, scalability, and availability features.

3. Explain the difference between General Purpose and Business Critical service tiers.

   • Answer: General Purpose offers a balance of compute and storage with good performance and scalability. Business Critical provides higher performance, higher availability (99.99%), and higher storage IOPS, suitable for mission-critical applications.

4. What is Hyperscale in Azure SQL Database?

   • Answer: Hyperscale is a service tier designed for massive scale and high throughput. It automatically scales storage and compute resources based on your database needs, offering virtually unlimited storage and extremely high scalability.

5. What is Azure SQL Managed Instance?

   • Answer: Azure SQL Managed Instance is a service tier that offers a near 100% compatibility with on-premises SQL Server, allowing you to migrate your on-premises databases with minimal code changes. It's ideal for large, complex databases requiring high compatibility.

6. Explain DTU (Database Transaction Units) and vCore purchasing models.

   • Answer: DTU is a bundled resource model that combines compute, memory, and I/O. vCore is a resource model that allows for independent scaling of compute, memory, and storage resources. vCore offers more granular control and scalability.

7. What is Elastic Pool in Azure SQL Database?

   • Answer: An elastic pool is a group of Azure SQL databases that share a pool of resources. It's cost-effective for managing multiple databases with varying workloads, as resources are shared efficiently.

8. How does Azure SQL Database ensure high availability?

   • Answer: Azure SQL Database utilizes techniques such as automatic failover, read replicas, and zone redundancy to ensure high availability and minimize downtime.

9. What are read replicas in Azure SQL Database?

   • Answer: Read replicas are secondary databases that are synchronized with the primary database. They are used to offload read operations, improving application performance and scalability.

10. What is geo-replication in Azure SQL Database?

    • Answer: Geo-replication enables you to replicate your Azure SQL Database to a secondary region for disaster recovery and low-latency access from other geographic locations.

11. Explain Azure SQL Database backups and restore options.

    • Answer: Azure SQL Database offers several backup options including full backups, differential backups, transaction logs, and point-in-time restore. These allow for data recovery and business continuity.

12. How can you monitor the performance of an Azure SQL Database?

    • Answer: Azure SQL Database offers built-in performance monitoring tools, including Azure portal dashboards, Azure Monitor, and Query Performance Insights. These tools provide insights into resource utilization, query performance, and potential bottlenecks.

13. What are some common performance tuning techniques for Azure SQL Database?

    • Answer: Common techniques include creating indexes, optimizing queries, using appropriate data types, partitioning large tables, and ensuring proper resource allocation (DTU or vCore).

14. How do you secure an Azure SQL Database?

    • Answer: Security measures include using strong passwords, enabling Azure Active Directory authentication, configuring network rules (firewall rules, virtual networks), using encryption (at rest and in transit), and regularly patching the database.

15. What is Azure SQL Database Auditing?

    • Answer: Azure SQL Database auditing provides a mechanism to track database activities, helping with security compliance, troubleshooting, and monitoring database usage.

16. Explain Transparent Data Encryption (TDE) in Azure SQL Database.

    • Answer: TDE encrypts the database files at rest, protecting data from unauthorized access even if the storage is compromised.

17. What is Always On Availability Groups?

    • Answer: Always On Availability Groups provide high availability and disaster recovery for SQL Server databases, including Azure SQL Database Managed Instance. They allow for automatic failover to a secondary replica in case of a primary replica failure.

18. How can you migrate an on-premises SQL Server database to Azure SQL Database?

    • Answer: Migration options include using the Azure Database Migration Service, Azure Data Factory, or manual scripting methods. The best method depends on the size and complexity of the database and desired downtime.

19. What are the benefits of using Azure SQL Database over on-premises SQL Server?

    • Answer: Benefits include reduced infrastructure management overhead, scalability and elasticity, high availability, enhanced security features, and cost optimization through pay-as-you-go pricing.

20. What are some common Azure SQL Database pricing considerations?

    • Answer: Pricing depends on the service tier (General Purpose, Business Critical, Hyperscale, Managed Instance), compute model (DTU or vCore), storage size, and other features like backups and geo-replication.

21. How can you optimize the cost of your Azure SQL Database?

    • Answer: Cost optimization strategies include choosing the right service tier and compute model, right-sizing resources based on actual workload needs, using elastic pools, and taking advantage of Azure Reserved Instances.

22. What is Azure SQL Database's role in hybrid cloud deployments?

    • Answer: Azure SQL Database can act as a target for migrating on-premises databases, providing a seamless integration between on-premises and cloud environments. It can also be used for extending on-premises applications to the cloud.

23. How does Azure SQL Database integrate with other Azure services?

    • Answer: Azure SQL Database integrates with many Azure services like Azure Active Directory, Azure Logic Apps, Azure Functions, Azure Data Factory, Azure Synapse Analytics, and Power BI for enhanced functionality and streamlined workflows.

24. Explain the concept of Azure SQL Database performance insights.

    • Answer: Performance Insights provides detailed information on query performance, including wait statistics and resource utilization. It helps identify performance bottlenecks and optimize queries for improved application performance.

25. What are the different authentication methods available for Azure SQL Database?

    • Answer: Authentication methods include SQL Server Authentication (using a username and password), Azure Active Directory Authentication (using Azure AD identities), and managed identities.

26. How can you implement row-level security in Azure SQL Database?

    • Answer: Row-level security (RLS) allows you to restrict access to rows in a table based on the user's identity. This enhances data security by preventing unauthorized access to sensitive data.

27. What is the purpose of Azure SQL Database vulnerability assessment?

    • Answer: Vulnerability assessment identifies potential security vulnerabilities in your Azure SQL Database, allowing you to proactively address them and improve the overall security posture.

28. Explain how to manage database users and permissions in Azure SQL Database.

    • Answer: Database users and permissions are managed through SQL Server Management Studio (SSMS), Azure portal, or Transact-SQL (T-SQL) commands. This involves creating users, assigning roles, and granting specific permissions on database objects.

29. How can you implement high availability for an Azure SQL Database application?

    • Answer: High availability can be implemented using read replicas, geo-replication, or Always On Availability Groups (for Managed Instance), depending on the requirements for failover time and geographic redundancy.

30. What are the best practices for designing a scalable Azure SQL Database?

    • Answer: Best practices include choosing the appropriate service tier and compute model, using indexing efficiently, optimizing queries, partitioning large tables, and using connection pooling.

31. Explain the concept of database sharding in Azure SQL Database.

    • Answer: Database sharding is a technique used to horizontally partition a large database into smaller, more manageable shards. This enhances scalability and performance for extremely large datasets.

32. How can you use Azure SQL Database with serverless compute?

    • Answer: Serverless compute allows you to pay only for the compute resources used during query execution. It's beneficial for applications with intermittent or unpredictable workloads.

33. What are the limitations of using Azure SQL Database?

    • Answer: Limitations can include vendor lock-in with Microsoft, potential cost increases with higher resource usage, and some limitations on customization compared to fully on-premises deployments.

34. Describe the process of setting up a connection string for Azure SQL Database.

    • Answer: A connection string includes the server name, database name, user ID, password, and other connection parameters. It’s used by applications to connect to the database. The specifics depend on the authentication method used.

35. How do you handle backups and restores of Azure SQL Database?

    • Answer: Backups and restores can be managed through the Azure portal, Azure CLI, PowerShell, or T-SQL. Azure manages the underlying storage, offering various backup options like full, differential, and log backups, along with point-in-time restore capabilities.

36. What is the difference between a single database and an elastic pool in Azure SQL Database?

    • Answer: A single database allocates resources exclusively to that database. An elastic pool shares resources among multiple databases, making it cost-effective for managing several databases with fluctuating workloads.

37. What are some strategies for ensuring data integrity in Azure SQL Database?

    • Answer: Strategies include using transactions, constraints (primary keys, foreign keys, unique constraints, check constraints), data validation rules, regular backups, and monitoring for data corruption.

38. How can you implement failover groups for high availability in Azure SQL Database?

    • Answer: Failover groups are not directly available in all Azure SQL Database service tiers. For high availability in single databases, you can use geo-replication. For Managed Instance, Always On Availability Groups provide advanced high availability and disaster recovery capabilities.

39. Explain the use of Azure SQL Database for disaster recovery.

    • Answer: Azure SQL Database offers several options for disaster recovery, including geo-replication, which creates a secondary database in a different region. This allows for quick failover in case of a regional outage.

40. How can you automate the management of Azure SQL Database using scripting?

    • Answer: Automation can be achieved using Azure CLI, PowerShell, and T-SQL scripts. These tools can automate tasks such as creating databases, managing users, configuring settings, and performing backups and restores.

41. What are the advantages of using Azure Data Studio for managing Azure SQL Database?

    • Answer: Azure Data Studio provides a cross-platform, open-source tool that allows for management of Azure SQL Database instances, along with other SQL Server instances. It offers a rich graphical user interface and facilitates many administrative tasks.

42. Discuss the use of Azure Key Vault for securing database connection strings.

    • Answer: Azure Key Vault is a secure storage service for secrets, including connection strings. Storing connection strings in Key Vault enhances security by preventing unauthorized access to sensitive information.

43. What are some tools available for monitoring and troubleshooting Azure SQL Database issues?

    • Answer: Tools include the Azure portal, Azure Monitor, Query Performance Insights, SQL Server Profiler, and extended events. These provide insights into performance, query execution, and potential issues.

44. Explain the concept of resource governance in Azure SQL Database.

    • Answer: Resource governance sets limits on resource consumption for databases or elastic pools, preventing runaway resource usage and ensuring predictable costs.

45. How can you improve the scalability of your Azure SQL Database application?

    • Answer: Strategies include scaling up (increasing DTUs or vCores), scaling out (adding more databases to an elastic pool or sharding), optimizing queries, using caching mechanisms, and load balancing.

46. What are the different types of indexes available in Azure SQL Database?

    • Answer: Types include clustered indexes, non-clustered indexes, unique indexes, filtered indexes, and spatial indexes. The choice depends on the query patterns and data access requirements.

47. Explain how to implement change data capture (CDC) in Azure SQL Database.

    • Answer: CDC tracks changes made to tables, allowing applications to monitor and process changes efficiently. It's useful for real-time data synchronization and reporting.

48. How can you monitor the health of your Azure SQL Database instance?

    • Answer: Monitoring tools include the Azure portal, Azure Monitor, and the built-in system views and functions within the database itself. These provide metrics on CPU, memory, I/O, and other key performance indicators.

49. Describe the process of upgrading an Azure SQL Database to a higher service tier.

    • Answer: Upgrading is done through the Azure portal, PowerShell, or CLI. It usually involves selecting the desired service tier and confirming the change. Downtime may be required depending on the upgrade process.

50. How can you manage storage size for your Azure SQL Database?

    • Answer: Storage size can be adjusted via the Azure portal, PowerShell, or CLI. Increasing the storage size is usually done online, but decreasing it might require downtime.

51. What are some best practices for query optimization in Azure SQL Database?

    • Answer: Best practices include using appropriate indexes, writing efficient queries, using proper data types, avoiding unnecessary joins, and utilizing query hints where necessary.

52. Explain the use of Azure Advisor for improving the performance and security of Azure SQL Database.

    • Answer: Azure Advisor provides recommendations to optimize the performance, cost, security, and availability of Azure resources, including Azure SQL Database. It analyzes your configuration and suggests improvements.

53. How can you use Azure Logic Apps with Azure SQL Database?

    • Answer: Azure Logic Apps can be used to integrate Azure SQL Database with other services and automate workflows. This can involve tasks such as data integration, ETL processes, and event-driven actions.

54. Discuss the importance of monitoring query execution statistics in Azure SQL Database.

    • Answer: Monitoring query execution statistics provides valuable insights into query performance, helping identify bottlenecks and areas for optimization. Tools such as Query Performance Insights are crucial for this.

55. What are the security considerations for managing user access to Azure SQL Database?

    • Answer: Security considerations involve using strong passwords, enforcing least privilege, employing multi-factor authentication (MFA), regularly auditing user activity, and implementing appropriate access control policies.

56. Explain how to use Azure Monitor to track metrics and logs from Azure SQL Database.

    • Answer: Azure Monitor collects metrics and logs from Azure SQL Database, providing comprehensive visibility into resource usage, performance, and operational health. These can be visualized through dashboards and analyzed for troubleshooting.

57. Describe the process of setting up a failover group for Azure SQL Database Managed Instance.

    • Answer: Setting up a failover group involves creating secondary Managed Instances in a different region, configuring the failover settings, and testing the failover process. Always On Availability Groups are used for this.

58. What are some strategies for migrating large databases to Azure SQL Database?

    • Answer: Strategies involve using the Azure Database Migration Service for minimal downtime, or employing techniques like data warehousing, data partitioning, and parallel processing to handle large datasets effectively.

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