Choose first by persistence model, then by database: EF Core is a provider-based object-relational mapper for conventional relational data access, while Marten and Polecat are document and event-sourcing libraries tied to PostgreSQL and SQL Server 2025, respectively. None is a universal winner; the right fit depends on the data model and database your team intends to operate.
What is the difference between EF Core, Marten, and Polecat?
| Decision point | EF Core | Marten | Polecat |
|---|---|---|---|
| Primary persistence model | Object-relational mapping using .NET entities, a context, and a database provider | Document database and event store implemented on PostgreSQL | Document database and event store backed by SQL Server 2025 |
| Database commitment | Depends on the selected provider; supported provider packages cover multiple database engines | PostgreSQL | SQL Server 2025 |
| Event sourcing | Not the defining capability in Microsoft’s EF Core overview | A central documented capability | A central documented capability |
| Getting started | Install the provider package and matching tooling | Install the Marten NuGet package |
Check Polecat’s documentation for current installation and release guidance |
How each option handles persistence
EF Core: relational mapping with provider choice
Microsoft describes EF Core as a lightweight, extensible, open-source, cross-platform ORM. You work with .NET objects through a model and context, then query and save data using a database provider. The provider ecosystem includes engines such as SQL Server, SQLite, PostgreSQL, MySQL/MariaDB, Oracle, Cosmos DB, and MongoDB. That breadth is a provider choice, not a guarantee that every provider has equivalent support or behavior. Microsoft’s EF Core overview and provider documentation advise checking provider quality, licensing, maintenance, and compatibility.
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Marten: documents and event streams on PostgreSQL
Marten is a .NET library for document-oriented persistence and event sourcing, implemented on PostgreSQL. Its approach uses PostgreSQL as a document database and event store while retaining PostgreSQL’s relational capabilities. The project describes this model in its introduction; its getting-started guide installs the Marten package with dotnet add package Marten and identifies PostgreSQL as its target: Marten getting started.
Polecat: a Marten-inspired model on SQL Server 2025
Polecat is a .NET document database and event-sourcing library backed by SQL Server 2025. Its documentation says its API patterns mirror Marten and that it uses SQL Server 2025’s native JSON type for documents and event data. See the Polecat documentation for its project description and current guidance.
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Which should you choose?
Choose based on the database you need to run
- PostgreSQL is the target and documents or event sourcing fit the domain: evaluate Marten.
- SQL Server 2025 is the target and documents or event sourcing fit the domain: evaluate Polecat.
- You need conventional relational object mapping, or may use different database engines: evaluate EF Core and the specific provider for each target.
These are architectural starting points, not automatic recommendations. If the application’s actual needs are relational mapping and provider flexibility, a specialized document/event-stream model may add a mismatch rather than solve a problem.
Decide whether document storage and event sourcing are requirements
Marten and Polecat make document persistence and event sourcing central capabilities. Adopt that model because it supports the application’s data and domain requirements—not simply because the libraries offer it. EF Core’s cited overview establishes it as an ORM; it does not establish event sourcing as its defining capability.
What should you verify before adopting one?
- Confirm the database and persistence model. Identify the database the team will operate and whether the application needs relational mapping, document storage, event sourcing, or a combination.
- Check the exact compatibility combination. Verify the chosen .NET, database, library, and provider versions against their current release guidance. Microsoft warns that EF Core providers typically do not cross major versions, so confirm provider compatibility before an upgrade. The EF Core installation guidance also says CLI and Package Manager Console tool major versions should match the runtime major version; that page was last updated March 23, 2023, so treat it as general package-workflow guidance rather than current release advice.
- For EF Core, assess the actual provider. Check its maintenance, licensing, quality, and compatibility rather than assuming the provider ecosystem is uniform.
- For Marten or Polecat, validate project and database readiness. Confirm current release guidance and that the required PostgreSQL or SQL Server 2025 features are available in your deployment environment.
- Test the work your system will do. Benchmark representative reads, writes, schema changes, and operational workflows using the application’s own workload before drawing conclusions about speed or cost.
Is one faster, more reliable, or cheaper?
The available project descriptions do not provide an apples-to-apples benchmark or comparable evidence for production reliability or total cost. Those outcomes depend on workload, schema and query patterns, database operations, and implementation. Treat a performance or cost ranking as unproven until it is measured against your application.
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