whichdb
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Db2 for i vs Microsoft SQL Server

Db2 for i: The relational database built into IBM i (AS/400), integrated with the OS and object security. Microsoft SQL Server: Microsoft's flagship RDBMS: T-SQL, columnstore, Always On, and now native vectors and JSON.

key differences

  • Microsoft SQL Server is built for larger datasets (≤ 1 PB) than Db2 for i (≤ 10 TB).
  • Horizontal scaling is none in Db2 for i and manual in Microsoft SQL Server.
  • Only Microsoft SQL Server has vector search, geospatial, change data capture, columnar storage, in-memory.

choose ibm-db2-for-i for

  • +ERP and distribution systems on IBM i
  • +Regional banking and insurance back ends
  • +Manufacturing execution and warehouse systems
  • +Exposing RPG business logic and data via SQL services and REST

best at · OLTP

choose sql-server 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

best at · OLTP, HTAP, Warehouse

Db2 for iThe relational database built into IBM i (AS/400), integrated with the OS and object security.
Microsoft SQL ServerMicrosoft's flagship RDBMS: T-SQL, columnstore, Always On, and now native vectors and JSON.
overview
Primary model
Relational
Relational
Also supports
Document
Document, Spatial, Vector, Graph, XML
Type
Database engine
Database engine
Status
Active
Active
Developer
IBM
Microsoft
First release
1988
1989
Latest version
IBM i 7.6 TR2 (Jul 2026)
2025 CU10 (17.0.5035.5) (Oct 22, 2026)
License
ProprietaryProprietary commercial license
ProprietaryMicrosoft commercial license
Free tier
—
✓
popularity
WhichDB Score
4.3
71.0
Rank
#410
#8
GitHub stars
–
–
Stack Overflow questions
999
336.2K
scale & guarantees
Comfortable data size
Medium (≤ 10 TB)
Large (≤ 1 PB)
Horizontal scaling
None
Manual
Multi-region
Read replicas
Read replicas
ACID
Full
Full
Consistency
Strong
Strong
Schema
Strict
Strict
Architecture
Single node, Multi primary, Shared storage
Client server, Primary replica, Shared storage
deployment
Self-hosted
✓
✓
Vendor-managed cloud
✓
✓
Serverless
—
—
Embedded
—
—
Edge
—
—
Clouds
IBM Cloud
Azure, AWS, Google Cloud
capabilities
Transactions
✓
✓
Joins
✓
✓
Secondary indexes
✓
✓
Full-text search
✓
✓
Vector search
—
✓
Geospatial
—
✓
JSON
✓
✓
Change data capture
—
✓
Triggers
✓
✓
Stored procedures
✓
✓
Materialized views
✓
✓
TTL / expiry
—
—
Pub/Sub
—
—
Columnar storage
—
✓
In-memory
—
✓
Durable persistence
✓
✓
Compression
✓
✓
Encryption at rest
✓
✓
Role-based access
✓
✓
Time travel
✓
✓
Branching
—
—
Online schema changes
—
✓
Streaming ingest
—
—
Offline sync
—
—
Runs in WebAssembly
—
—
interfaces
Query languages
SQL, SQL PL, RPG record-level access
T-SQL
Client languages
RPG, COBOL, Java, Python, JavaScript, C#, PHP
C#, Java, Python, JavaScript, Go, PHP, Rust, C
Best for
OLTP
OLTP, HTAP, Warehouse, Real-time analytics
Add more to this comparisonNot sure either fits? Try smart match

Db2 for i vs Microsoft SQL Server: FAQ

What is the difference between Db2 for i and Microsoft SQL Server?

Db2 for i: The relational database built into IBM i (AS/400), integrated with the OS and object security. Microsoft SQL Server: Microsoft's flagship RDBMS: T-SQL, columnstore, Always On, and now native vectors and JSON. Microsoft SQL Server is built for larger datasets (≤ 1 PB) than Db2 for i (≤ 10 TB). Horizontal scaling is none in Db2 for i and manual in Microsoft SQL Server. Only Microsoft SQL Server has vector search, geospatial, change data capture, columnar storage, in-memory.

When should I choose Db2 for i over Microsoft SQL Server?

Choose Db2 for i for ERP and distribution systems on IBM i; regional banking and insurance back ends; and manufacturing execution and warehouse systems. Choose Microsoft SQL Server for line-of-business apps in .NET shops; ERP and CRM back ends (Dynamics, many ISV products); and operational reporting with columnstore indexes.

Is Db2 for i or Microsoft SQL Server more popular?

Microsoft SQL Server ranks #8 on the WhichDB Score (71.0/100) and Db2 for i ranks #410 (4.3/100). Popularity is not fit: check the requirements that matter for your project.

Are Db2 for i and Microsoft SQL Server open source?

No. Db2 for i is proprietary, closed-source software. No. Microsoft SQL Server is proprietary, closed-source software. License: Microsoft commercial license.