Azure SQL Database Interview Questions and Answers for 10 years experience

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100 Azure SQL Database Interview Questions & Answers (10+ Years Experience)

  1. What are the different service tiers available in Azure SQL Database? Explain their key differences.

    • Answer: Azure SQL Database offers various service tiers catering to different performance and scalability needs. These include: Basic (deprecated), Standard, General Purpose, Business Critical, and Hyperscale. Key differences lie in compute, storage, IOPS, DTUs/vCores, and high availability features. Standard and General Purpose offer good balance of cost and performance. Business Critical provides higher availability and performance with high redundancy. Hyperscale is designed for massive scale and elasticity, handling terabytes of data and extreme workloads. The choice depends on the application's requirements and budget.

  2. Explain the concept of DTUs and vCores in Azure SQL Database. When would you choose one over the other?

    • Answer: DTUs (Database Transaction Units) represent a bundled measure of compute, memory, and I/O resources. vCores represent dedicated cores providing more granular control over resource allocation. DTUs are simpler to manage but less flexible, while vCores offer greater scalability and customization. Choose DTUs for simpler applications with predictable workloads. Opt for vCores for demanding applications needing fine-tuned performance and scalability.

  3. Describe different deployment models for Azure SQL Database.

    • Answer: Azure SQL Database offers different deployment models: Single database, Elastic pool, and Managed Instance. Single databases are isolated instances ideal for smaller applications. Elastic pools are collections of databases sharing resources, cost-effective for multiple databases with varying workloads. Managed Instances provide more control and compatibility with on-premises SQL Server, suitable for migrating complex applications.

  4. How do you ensure high availability and disaster recovery for Azure SQL Database?

    • Answer: High availability and disaster recovery are achieved using features like Geo-replication (synchronous and asynchronous), read replicas, and Availability Groups. Geo-replication provides disaster recovery to a secondary region. Read replicas improve performance by offloading read traffic. Availability Groups offer high availability within a region by providing automatic failover to a secondary replica. The choice depends on RTO and RPO requirements.

  5. Explain Azure SQL Database's security features.

    • Answer: Azure SQL Database offers robust security features: Azure Active Directory integration for authentication, firewall rules to restrict access, encryption (Always Encrypted, Transparent Data Encryption), row-level security, dynamic data masking, and threat detection to monitor suspicious activities. These features protect data from unauthorized access and ensure compliance with security standards.

  6. How do you perform database backups and restores in Azure SQL Database?

    • Answer: Backups can be managed through Azure portal, PowerShell, or Azure CLI. Azure offers various backup options: full, differential, and transaction log backups. Point-in-time restore allows restoring to a specific point in time. Geo-restore enables restoring a database to a different region for disaster recovery. Automated backups are highly recommended.

  7. Describe different performance tuning techniques for Azure SQL Database.

    • Answer: Performance tuning involves various techniques: optimizing queries using execution plans, indexing, and statistics updates; proper resource allocation (DTUs/vCores); using appropriate service tier; implementing caching strategies; and monitoring performance metrics using tools like Query Performance Insight and Azure SQL Database Performance Advisor. Regularly reviewing and optimizing queries and indexes is crucial.

  8. Explain the concept of Azure SQL Database Managed Instances.

    • Answer: Managed Instances provide a nearly identical experience to on-premises SQL Server. They offer enhanced compatibility, allowing easier migration and reduced changes to applications. They also offer the benefits of Azure's managed services, including patching, backups, and high availability.

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