Azure SQL Database vs Azure SQL Managed Instance: What are the differences?

Introduction

Azure SQL Database and Azure SQL Managed Instance are two options for deploying and managing relational databases on the Azure cloud platform. While both options offer similar functionality, there are key differences that differentiate them.

1. Deployment Model: Azure SQL Database uses a multi-tenant deployment model where multiple databases are hosted on a single server, while Azure SQL Managed Instance uses a single-tenant deployment model where each instance gets dedicated resources. This makes Azure SQL Managed Instance more suitable for scenarios where more control over server-level resources is required.

2. Compatibility: Azure SQL Database is based on the latest version of the SQL Server database engine and offers high compatibility with on-premises SQL Server. Azure SQL Managed Instance, on the other hand, is designed to provide the closest compatibility with on-premises SQL Server, including support for features like SQL Agent and cross-database queries. This makes Azure SQL Managed Instance a better choice for migrating existing on-premises databases to the cloud without making extensive code changes.

3. Management: Azure SQL Database provides a fully managed database service, with automated backups, patching, and maintenance handled by Microsoft. Azure SQL Managed Instance, while still a fully managed service, offers more control over the instance-level management tasks. This includes the ability to perform instance-level backups and adjust instance-level settings such as assigning network security groups and configuring firewall rules.

4. Scalability: Both Azure SQL Database and Azure SQL Managed Instance offer built-in scaling capabilities. However, Azure SQL Managed Instance provides more granular control over resources with options such as increasing compute and storage independently, enabling better performance tuning. This makes Azure SQL Managed Instance a better choice for applications that have unpredictable workloads and require fine-tuning of resources.

5. Pricing: Azure SQL Database offers various pricing tiers with different performance and features, allowing customers to choose the most suitable option based on their requirements and budget. Azure SQL Managed Instance, on the other hand, has a dedicated pricing model based on vCores and storage consumed by the instance. This makes Azure SQL Managed Instance more cost-effective for applications that require higher levels of performance and resources.

6. Networking: In Azure SQL Database, the databases are accessed using a server-level endpoint and connections are made directly to the individual databases. In Azure SQL Managed Instance, the instance is accessed using a dedicated instance-level endpoint, and connections are made to the instance itself, which then routes the requests to the appropriate database. This provides greater control over network-level security in Azure SQL Managed Instance.

In summary, Azure SQL Database and Azure SQL Managed Instance offer different deployment models, compatibility levels, management capabilities, scalability options, pricing models, and networking architectures. The choice between the two depends on specific application requirements, control needs, and budget considerations.