SQL Server on Azure VM vs Azure SQL Managed Instance vs Azure SQL Database vs Azure Database for MySQL/PostgreSQL
Verdict: Only SQL Server on an Azure VM is IaaS, leaving OS and engine patching to you. Among PaaS, match the engine: SQL Server compatibility needs Managed Instance or SQL Database; a MySQL or PostgreSQL app needs the matching open-source service.
| Criterion | SQL Server on Azure VM | Azure SQL Managed Instance | Azure SQL Database | Azure Database for MySQL/PostgreSQL |
|---|---|---|---|---|
| Management model | IaaS, customer-managed | PaaS, fully managed | PaaS, fully managed | PaaS, fully managed |
| OS/patching responsibility | Customer patches OS and SQL Server | Automated by Microsoft | Automated by Microsoft | Automated by Microsoft |
| Compatibility surface | Full on-premises SQL Server compatibility | Near-100% SQL Server compatibility | Core SQL Server database-level capabilities, not all instance-level features | Native MySQL or PostgreSQL engine, not SQL Server |
| Best for | Migrations or apps needing full OS-level access | Migrating instance-level SQL Server features with minimal change | New cloud apps needing the lowest administration | Existing MySQL or PostgreSQL apps moving without rewrite |
Rules
- SQL Server on an Azure VM is IaaS: the customer manages the operating system and SQL Server, including updates, configuration, and backups.
- Azure SQL Managed Instance offers near-100% SQL Server compatibility, letting most databases migrate with minimal code change while updates and backups are automated.
- Azure SQL Database is the fully managed PaaS option recommended for new cloud applications, giving the lowest administration overhead.
- Azure Database for MySQL and Azure Database for PostgreSQL are PaaS implementations of the native open-source engines, letting existing MySQL or PostgreSQL apps move to Azure without significant changes.
- Flexible Server is the recommended, fully managed deployment option for new MySQL and PostgreSQL workloads, giving more granular configuration control.
- SQL Server on Azure VMs is the only one of the four where the customer decides when to update or upgrade the operating system and SQL Server software.
Traps
- Do not assume the VM and PaaS options automate patching the same way. Only the PaaS options automate OS and engine updates; the VM leaves both to the customer.
- Do not assume Azure SQL Database fully replicates on-premises SQL Server. It supports core database-level capabilities, but some instance-level features it depends on may be missing.
- Do not pick Managed Instance for a brand-new cloud app. It targets migrating existing SQL Server workloads with minimal change, not new projects wanting the lowest administration.
- Do not assume Azure Database for MySQL or PostgreSQL secretly run SQL Server under another name. They run the native open-source engines and support standard SQL against them.