Microsoft SQL Server
activeby Microsoft · since 1989 · also known as SQL Server, MSSQL, MS SQL, SQL Server 2025
Microsoft's flagship RDBMS: T-SQL, columnstore, Always On, and now native vectors and JSON.
Overview
SQL Server is the default relational database of the Microsoft world, running on Windows and Linux and sharing its engine with Azure SQL. It is a strong all-rounder: row and columnstore indexes in one database, In-Memory OLTP, temporal tables, Always On availability groups and very good tooling (SSMS, Query Store). SQL Server 2025 (GA November 2025) added a native vector type with DiskANN indexing, a native JSON type, regex functions and change event streaming. It is the obvious choice for .NET and Windows-heavy shops; the costs are per-core licensing, the fact that its best features sit in Enterprise Edition, and no built-in way to scale writes horizontally.
Strengths & trade-offs
Strengths
- +Columnstore and rowstore indexes on the same tables give real HTAP without ETL
- +Query Store, Intelligent Query Processing and SSMS make performance work approachable
- +Always On availability groups provide automatic failover with readable secondaries
- +Native vector type and DiskANN index in 2025 put semantic search next to relational data
- +Same engine as Azure SQL, so lift-and-shift to Microsoft's cloud is straightforward
- +Deep integration with .NET, Entra ID, Power BI and the wider Microsoft stack
Trade-offs
- −Per-core Enterprise licensing gets expensive quickly on large servers
- −No native horizontal write scaling or sharding
- −Linux support lags Windows for some features (e.g., certain HA and integration services)
- −T-SQL dialect and features tie applications to Microsoft
Great for
- +Line-of-business apps in .NET shops
- +ERP and CRM back ends (Dynamics, many ISV products)
- +Operational reporting with columnstore indexes
- +Departmental data marts feeding Power BI
- +Hybrid on-prem and Azure deployments via Azure Arc
Think twice for
- −Globally distributed, multi-region write workloads
- −Budget projects that need Enterprise-only features
- −Petabyte-scale analytics (use a cloud warehouse)
Capabilities
Native or official first-party support · 19 of 25 tracked
Scale & consistency
- Comfortable data size
- Large · ≤ 1 PB
- Horizontal scaling
- Manual
- Multi-region
- Read replicas
- Transactions
- Full ACID
- Consistency
- Strong
- Schema
- Strict
- Architecture
- Client server, Primary replica, Shared storage
- Query languages
- T-SQL
Scales up well; readable secondaries and distributed availability groups for reads/DR. Write scale-out requires app-level sharding.
Deployment
available on · Azure · AWS · Google Cloud
Ecosystem
Alternatives to Microsoft SQL Server
The extensible, standards-first open-source relational database.
sql-server vs postgresql →The enterprise heavyweight: RAC, Data Guard and a converged engine for SQL, JSON, graph and vectors.
sql-server vs oracle-database →Microsoft's always-current managed SQL Server engine, from free serverless databases to 128 TB Hyperscale.
sql-server vs azure-sql-database →The web's default open-source SQL database, now on calendar versioning with 9.7 as the LTS line.
sql-server vs mysql →IBM's enterprise RDBMS for Linux, UNIX, Windows and z/OS, with BLU columnar and pureScale clustering.
sql-server vs ibm-db2 →AWS's MySQL- and PostgreSQL-compatible engine on a shared, six-way replicated storage layer.
sql-server vs amazon-aurora →Microsoft SQL Server FAQ
What is Microsoft SQL Server?
Microsoft SQL Server is a relational database by Microsoft, first released in 1989. SQL Server is the default relational database of the Microsoft world, running on Windows and Linux and sharing its engine with Azure SQL. It is a strong all-rounder: row and columnstore indexes in one database, In-Memory OLTP, temporal tables, Always On availability groups and very good tooling (SSMS, Query Store). SQL Server 2025 (GA November 2025) added a native vector type with DiskANN indexing, a native JSON type, regex functions and change event streaming. It is the obvious choice for .NET and Windows-heavy shops; the costs are per-core licensing, the fact that its best features sit in Enterprise Edition, and no built-in way to scale writes horizontally.
Is Microsoft SQL Server open source?
No. Microsoft SQL Server is proprietary, closed-source software. License: Microsoft commercial license.
Does Microsoft SQL Server support ACID transactions?
Yes. Microsoft SQL Server supports full ACID transactions, with strong consistency.
Does Microsoft SQL Server scale horizontally?
Microsoft SQL Server has no built-in sharding; scaling out means partitioning data in your application. It is comfortable at large scale (≤ 1 PB). It supports cross-region read replicas.
How can I run Microsoft SQL Server?
You can self-host it and use the vendor's managed cloud. Managed offerings include Azure SQL Managed Instance, Amazon RDS for SQL Server and Cloud SQL for SQL Server. It is available on Azure, AWS and Google Cloud.
What is Microsoft SQL Server best for?
Microsoft SQL Server is a strong fit for line-of-business apps in .NET shops; ERP and CRM back ends (Dynamics, many ISV products); and operational reporting with columnstore indexes. Think twice for globally distributed, multi-region write workloads.
What are the best alternatives to Microsoft SQL Server?
Common alternatives to Microsoft SQL Server include PostgreSQL, Oracle Database, Azure SQL Database, MySQL and IBM Db2. The right choice depends on your workload, scale and hosting; WhichDB's smart match ranks them against your requirements.
How popular is Microsoft SQL Server?
Microsoft SQL Server ranks #8 of 844 databases on the WhichDB Score (71.0/100), and #4 among relational databases. The score combines public adoption signals such as package downloads, GitHub activity, job posts and developer discussion.