Microsoft Azure SQL Database Interview Questions and answers

Top all Microsoft Azure SQL Database Interview Questions and answers?

Here’s a comprehensive list of top Microsoft Azure SQL Database interview questions along with their answers. These questions cover a range of topics including fundamental concepts, security, performance, and more.

1. What is Azure SQL Database?

Answer: Azure SQL Database is a fully managed relational database service provided by Microsoft Azure. It is based on SQL Server and offers a range of features including scalability, high availability, and security. Azure SQL Database abstracts the infrastructure management and allows users to focus on database development and performance.

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

Answer: Azure SQL Database offers several service tiers, each with different performance and pricing options:

• General Purpose: Balanced compute and storage options for most workloads.
• Business Critical: High performance with low-latency and high I/O operations, using a premium storage architecture.
• Hyperscale: Scales up to very large databases and provides high performance with elastic scaling.

Each tier is designed to meet different needs based on performance, availability, and cost.

3. How do you scale an Azure SQL Database?

Answer: You can scale an Azure SQL Database in several ways:

• Compute Resources: Adjust the DTU (Database Transaction Unit) or vCore (virtual core) configuration to increase or decrease compute power and memory.
• Storage: Increase the allocated storage space through the Azure portal or using T-SQL commands.
• Service Tiers: Change the service tier to align with your performance and cost requirements.

4. What is the difference between DTU and vCore models in Azure SQL Database?

Answer:

• DTU (Database Transaction Unit): A blended measure of compute, memory, and I/O resources. It simplifies performance management by providing a predefined set of resources.
• vCore (Virtual Core): Offers more flexibility by allowing users to select the number of virtual cores and amount of memory independently. It also provides the option to choose between standard and premium storage.

5. How do you implement high availability in Azure SQL Database?

Answer: Azure SQL Database provides high availability through:

• Built-in high availability: Each database is automatically replicated to multiple locations within the same region, ensuring continuous availability.
• Active Geo-Replication: Allows you to create readable secondary replicas in different regions for disaster recovery and load balancing.
• Auto-failover groups: Automatically manage failover of multiple databases to ensure high availability.

6. What are the security features provided by Azure SQL Database?

Answer: Azure SQL Database includes several security features:

• Firewall Rules: Restrict access based on IP addresses.
• Virtual Network Service Endpoints: Restrict access to databases from specific Azure Virtual Networks.
• Advanced Threat Protection: Detect and respond to potential threats and vulnerabilities.
• Transparent Data Encryption (TDE): Encrypt data at rest.
• Always Encrypted: Encrypt sensitive data in transit and at rest.
• Auditing: Track database events and changes.

7. How do you monitor performance in Azure SQL Database?

Answer: Performance monitoring in Azure SQL Database can be done using:

• Azure Monitor: Provides comprehensive monitoring with logs and metrics.
• SQL Database Query Performance Insight: Helps analyze and optimize query performance.
• Query Store: Tracks query performance and execution statistics.
• Automatic Tuning: Offers performance recommendations and automatic index management.

8. What is the role of the Query Store feature in Azure SQL Database?

Answer: The Query Store feature helps in tracking and analyzing query performance over time. It captures historical query performance data, allows you to monitor and diagnose performance issues, and provides insights into query execution plans. This feature helps in identifying and addressing performance regressions and anomalies.

9. Explain the concept of Geo-Replication in Azure SQL Database.

Answer: Geo-Replication allows you to create readable secondary replicas of your database in different Azure regions. This helps in:

• Disaster Recovery: Providing failover capability in case of regional outages.
• Load Balancing: Distributing read queries across multiple regions to reduce latency.
• Data Residency Compliance: Ensuring data compliance by keeping copies in specific regions.

10. What is Elastic Pool in Azure SQL Database?

Answer: Elastic Pools are a cost-effective solution to manage and scale multiple databases that have varying and unpredictable usage patterns. They allow you to allocate a shared set of resources (DTUs or vCores) among multiple databases, optimizing performance and cost-efficiency by providing a buffer for resource utilization spikes.

11. How do you handle database migrations to Azure SQL Database?

Answer: Database migrations can be handled using several tools and strategies:

• Azure Database Migration Service (DMS): Facilitates seamless migration from various sources to Azure SQL Database.
• SQL Server Management Studio (SSMS): Use the Data Migration Assistant (DMA) and SQL Server Migration Assistant (SSMA) tools.
• BACPAC Files: Export and import database schemas and data using BACPAC files.

12. What is the purpose of SQL Database Auditing in Azure?

Answer: SQL Database Auditing tracks database events and changes to help ensure compliance with security policies and regulations. It provides detailed audit logs that can be reviewed to identify unauthorized access, detect suspicious activity, and understand how data is being accessed and modified.

13. How does Azure SQL Database handle data backups?

Answer: Azure SQL Database provides automated backups that include:

• Full Backups: Taken weekly, retained for up to 35 days.
• Differential Backups: Taken every 12-24 hours, retained for up to 35 days.
• Transaction Log Backups: Taken every 5-10 minutes, retained for up to 35 days.

These backups ensure point-in-time restore capabilities and help in data recovery and disaster recovery scenarios.

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

Answer: Common performance tuning techniques include:

• Indexing: Creating and optimizing indexes to speed up query performance.
• Query Optimization: Analyzing and rewriting slow queries, and utilizing Query Store insights.
• Database Design: Normalizing schema and using proper data types.
• Resource Scaling: Adjusting DTUs or vCores based on performance needs.
• Caching: Leveraging caching mechanisms to reduce database load.
  
  

15. What are the considerations for pricing and cost management in Azure SQL Database?

Answer: Cost management considerations include:

• Service Tier Selection: Choose the appropriate service tier based on performance and budget.
• Scaling: Adjust compute and storage resources as needed to optimize costs.
• Monitoring: Use Azure Cost Management to track and analyze spending.
• Elastic Pools: Use elastic pools to optimize costs for multiple databases with varying workloads.

16. How does Azure SQL Database handle disaster recovery?

Answer: Azure SQL Database handles disaster recovery through several features:

• Auto-Failover Groups: Provide automatic failover of multiple databases to a secondary server in case of a regional outage.
• Active Geo-Replication: Allows for up to four readable secondary databases in different regions, providing high availability and disaster recovery.
• Zone Redundant Configuration: Offers additional resiliency by distributing database replicas across different availability zones within the same region.

17. What is the role of the SQL Database Advisor in Azure SQL Database?

Answer: The SQL Database Advisor provides recommendations for optimizing the performance, security, and reliability of your Azure SQL Database. It offers insights into areas such as indexing, query performance, and resource utilization. These recommendations help you implement best practices and improve the overall efficiency of your database.

18. Explain the concept of "serverless" in Azure SQL Database.

Answer: The serverless tier in Azure SQL Database automatically scales compute resources based on workload demand and pauses during inactivity to save costs. It is designed for databases with intermittent and unpredictable usage patterns. You are billed based on the resources consumed rather than a fixed amount, providing cost-efficiency and scalability.

19. How does Azure SQL Database ensure data encryption at rest and in transit?

Answer:

• Encryption at Rest: Azure SQL Database uses Transparent Data Encryption (TDE) to automatically encrypt database files, backups, and transaction logs at rest. TDE encrypts data using a symmetric key, and this key is itself protected by a built-in Azure Key Vault.
• Encryption in Transit: Azure SQL Database uses Transport Layer Security (TLS) to encrypt data transmitted between the client and the database server, ensuring data integrity and confidentiality during communication.

20. How does Azure SQL Database integrate with Azure Key Vault?

Answer: Azure SQL Database integrates with Azure Key Vault to manage and protect encryption keys. Key Vault can be used to manage encryption keys for Transparent Data Encryption (TDE) and Always Encrypted columns. This integration enhances security by centralizing key management and ensuring compliance with security policies.

21. What are the key differences between SQL Database Managed Instances and Azure SQL Database?

Answer:

• SQL Database Managed Instances: Offer a more comprehensive feature set with compatibility for SQL Server on-premises, including support for SQL Server Agent, cross-database queries, and SQL Server Management Studio (SSMS) integration. It provides a near-100% compatibility with on-premises SQL Server.
• Azure SQL Database: Is a platform-as-a-service (PaaS) offering with a focus on cloud-native features, offering a more streamlined set of functionalities designed for cloud environments. It is suitable for modern cloud applications and includes advanced features like serverless and hyperscale.

22. How do you manage database schema changes in Azure SQL Database?

Answer: Schema changes in Azure SQL Database can be managed using:

• SQL Server Data Tools (SSDT): For developing, deploying, and managing database schemas.
• Azure DevOps: Integrates with Continuous Integration/Continuous Deployment (CI/CD) pipelines for automating schema changes.
• Database Projects: Allows for version control and deployment of schema changes using SQL scripts or dacpac files.
• Schema Compare Tool: Helps in comparing and synchronizing database schemas across environments.

23. What is the role of the “Query Performance Insight” tool in Azure SQL Database?

Answer: Query Performance Insight provides visibility into query performance by displaying historical query execution details. It helps identify long-running queries, view resource consumption patterns, and analyze execution plans. This tool is useful for diagnosing performance issues and optimizing queries to improve database performance.

24. What are the benefits of using an Azure SQL Database Hyperscale service tier?

Answer: The Hyperscale service tier offers several benefits:

• Elastic Scaling: Automatically scales up to accommodate large databases and high-performance requirements.
• High Performance: Provides high I/O performance and low latency for large databases.
• Instantaneous Backup and Restore: Enables rapid backup and restore operations without impacting performance.
• Storage Capacity: Supports databases up to 100 TB in size, allowing for large-scale applications and data warehousing solutions.

25. What is "Always Encrypted" in Azure SQL Database, and how does it work?

Answer: Always Encrypted is a feature that ensures sensitive data is encrypted both in transit and at rest. It uses encryption keys managed outside of SQL Server, enhancing security by ensuring that data is encrypted before it is sent to the database. Only authorized applications with the appropriate decryption keys can view the data, protecting it from unauthorized access.

26. How does Azure SQL Database handle long-running transactions?

Answer: Azure SQL Database handles long-running transactions by:

• Transaction Log Management: Using transaction logs to maintain data consistency and support recovery.
• Lock Management: Implementing various lock levels (e.g., shared, exclusive) to manage concurrent access and prevent contention.
• Resource Governor: Enforcing limits on resource usage to prevent long-running transactions from monopolizing resources and impacting performance.

27. How do you implement data masking in Azure SQL Database?

Answer: Dynamic Data Masking (DDM) in Azure SQL Database helps to protect sensitive data by masking it in query results. You can configure masking rules on specific columns to control how data is displayed to users. For example, you can mask credit card numbers or personal information so that users only see masked values.

28. What is the "serverless" model in Azure SQL Database and when would you use it?

Answer: The serverless model in Azure SQL Database automatically scales compute resources based on workload demands and pauses during inactivity. It is ideal for databases with unpredictable or intermittent usage patterns. It reduces costs by charging only for the resources consumed and allows databases to scale up and down without manual intervention.

29. Can you explain the concept of "Index Advisor" and how it can benefit Azure SQL Database performance?

Answer: Index Advisor provides recommendations for creating, dropping, or modifying indexes based on database workload analysis. By analyzing query patterns and performance metrics, it suggests indexes that can improve query performance and reduce resource contention. Implementing these recommendations can optimize database performance and efficiency.

30. What are "Failover Groups" and how do they contribute to high availability in Azure SQL Database?

Answer: Failover Groups in Azure SQL Database enable automatic failover for multiple databases within a group. They are used to ensure high availability and disaster recovery by automatically failing over all databases in the group to a secondary server in case of a regional outage. This feature simplifies managing high availability across multiple databases and ensures minimal downtime.

These questions and answers should provide a well-rounded understanding of Azure SQL Database's features, capabilities, and best practices, and prepare you for more advanced discussions in interviews.