SQL Managed Instance vs Azure SQL Database
Before comparing SQL Managed Instance and Azure SQL Database, let’s get the similarities out of the way first. To begin with, they both have the same code base with the latest version of SQL Server. Therefore, the SQL language is the same, with identical DBMS features and query processing.
As for differences, there are quite a few. For example, SQL Managed Instance uses web browser tools for backup commands, whereas Azure SQL database uses automated backups. And while Azure SQL database supports CLR, SQL Managed Instance does not.
What Is the Difference Between Azure SQL Database and SQL Managed Instance?
Azure SQL Database falls under the category of Platform as a Service (PaaS) database engines and is a relational, in-memory type. It offers features such as data-loss prevention, frequent updates, vulnerability assessment, and data encryption.
SQL Managed Instance is a fully functioning PaaS cloud database that follows TCP protocol for connectivity. Features unique to SQL Managed Instance are database collation, partitioning, and online index operations.
Here’s a comprehensive walkthrough of the differences between these two in terms of features.
| Feature | SQL Managed Instance | Azure SQL Database |
| Backup Command | Supports user-initiated copy-only backups to Azure Blob storage. However, the user cannot initiate automatic system backups on their own. | There is no support for user-initiated system backups. Only system-initiated automatic backups are allowed. |
| Auditing | Auditing works at the server level. | Auditing works at the database level. |
| Azure Active Directory (AD) authentication | Authentication is available for Azure AD users as well as server-level AD logins. | Authentication is available only for Azure AD users. |
| Change Data Capture (CDC) | CDC is supported across the board. | CDC is supported for tiers above S3, but not for S0, S1, and S2 tiers. |
| Common Language Runtime (CLR) | Supports CLR for Azure Key Vault and Shared Access Signature only | Does not support CLR |
| Cross-database Transactions | Supported within the instance | Not supported |
| Database mail (DbMail) | Yes | No |
| Database Virtualization | Yes, available | Not available |
| DDL Triggers | Yes | Yes, database only |
| Distributed Transactions – MS DTC | Supports DTC for Azure SQL Managed Instance | DTC not supported |
| Elastic Query | Users have to use Linked Server and native cross-database queries instead of elastic queries. | Users can use elastic queries. |
| Files and filegroups | File paths get assigned without user intervention but users cannot specify file location using the ALTER DATABASE ADD FILE statement. | Only primary filegroups |
| In-memory Optimization | Only Business Critical service tier supports In-memory optimization | In-memory OLTP objects are supported in the Hyperscale service tier, but limited to memory-optimized table variables.Full support in Premium service tierFull support in Business Critical service tier |
| Linked Servers | Support is limited to SQL Server and SQL Database without distributed transactions | Not supported |
| Modifying system data | Possible | Not possible |
| Hyperscale Architecture | Not supported | Supported |
| Polybase | Supports polybase for Azure Blob Storage as data source and Azure Data Lake Storage (ADLS) | Users can query data in the files that are on blob storage, but polybase is not supported. |
| Query Notifications | Yes | No |
| Resource Governor | Available | Unavailable |
| Data Restore | User can restore data from automated backups and backups stored on blob storage | User can restore data only from automated backups |
| Tuning | Does not support automatic tuning | Supports automatic tuning |
| Scaling | No support for auto-scale | Auto-scale available in serverless models |
| Active geo-replication | Not available. Users may consider using Auto-failover groups. | Available across all service tiers |
| Pause/resume | No | Yes (serverless model) |
Below is an overview of the differences between SQL Managed Instance and Azure SQL Database in terms of resource limits.
| Category | SQL Managed Instance | Azure SQL Database |
| Storage | Up to 16 TB | From 1 GB to maximum 100 TB |
| Tempdb Size | 4 TB max | Up to 2,560 GB (32 GB per vCore) |
| Log Write Throughput | Up to 48 MB/s per vCore | Up to 100mb/sec |
Frequently Asked Questions
What Are the Limitations of SQL Managed Instance?
SQL Managed Instance has the following limitations.
- Slower process completion.
- Number of databases is limited.
- Maximum storage size can seem compromised.
- No Active geo-replication.
What Is the Limitation of Azure SQL Database?
Azure SQL Database has its upsides, like no physical hardware requirements, a wide variety of data options, and affordability. However, it is not without drawbacks, such as:
- No support for Linked Servers.
- The database transaction units in Azure SQL Database can be a bit confusing to new users.
- Windows Authentication is not available.
- Automatic tuning and Auto-scale are absent.
- It does not support Common Language Runtime.
Conclusion
The advantages of SQL Managed Instance are quite a few compared to Azure SQL Database. And the fact that it supports Cross-database Transactions and Linked Servers deserves a big thumbs up. However, SQL Database does offer better flexibility when it comes to upgrading existing plans. Plus, the pricing is better too.
