Draft release notes

The team has been working primarily on EF Core internals, so there are no new big features in EF Core 9 (EF9) Preview 4. However, this means we really need people like you to run your code on these new internals and report back what you find. We want to fix bugs in the new internals as soon as possible in order to have a strong GA release later in the year.

That being said, there are several smaller enhancements included in preview 4. For full details, see What's new in EF Core 9. To discuss the EF9 release, go to Try EF Core 9 now! on GitHub.

Enhanced database provider for Azure Cosmos DB for NoSQL

We are working on significant updates in EF9 to the EF Core database provider for Azure Cosmos DB for NoSQL. For preview 4, these include:

• Role-based access control (RBAC) is supported by EF9 for both management and use of containers.
• Azure Cosmos DB for NoSQL does not support synchronous (blocking) access from application code. EF Core now blocks synchronous access by default, helping people fall into the pit-of-success of using async I/O.
• Cosmos primitive collection support has been updated to use the metadata and model building APIs from EF8

See Azure Cosmos DB for NoSQL in the What's New docs for more information.

GroupBy complex types

In preview 4, EF9 now supports grouping (GroupBy queries) that group by a complex type instance. The resulting SQL uses groups by all members, reflecting the value object semantics of complex types.

See GroupBy complex types in the What's New docs for more information.

Read-only primitive collections

EF8 introduced support for mapping arrays and mutable lists of primitive types. This has been expanded in EF9 to include read-only collections declared as IReadOnlyList, IReadOnlyCollection, or ReadOnlyCollection.

See Read-only primitive collections in the What's New docs for more information.

Everything else in preview 4

Preview 4 contains:

• 10 enhancements
• 15 bug fixes

EF Core 9 preview 4 (and Microsoft.Data.Sqlite) contains work from the EF Team at Microsoft (@roji @AndriySvyryd @maumar @ajcvickers @cincuranet @SamMonoRT @luisquintanilla) as well as contributions from the EF Core community. The community PRs in EF9 Preview 4 are:

• @y0ung3r: InMemoryTable: Make IsConcurrencyConflict() method more readable