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.