cosmos-provider

Development

Implementation details for the EF Core Azure Cosmos DB provider. Use when changing Cosmos-specific code.

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Source SKILL.md: https://github.com/dotnet/efcore/blob/HEAD/.agents/skills/cosmos-provider/SKILL.md

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Cosmos DB Provider

Non-relational provider with its own parallel query pipeline. Uses JSON for document materialization.

Key Differences from Relational

No migrations — use EnsureCreated()
Documents as JSON — owned and complex types become embedded objects
Partition key configuration required for performance
ETag for optimistic concurrency
No cross-container joins

Azure Cosmos DB Emulator for Tests

TestEnvironment.InitializeAsync() auto-starts a Testcontainers.CosmosDb container when Test__Cosmos__DefaultConnection is not set. Set the env var to use an existing emulator instead.
Skip tests requiring unsupported features on the Linux emulator with [ConditionalFact(typeof(CosmosTestEnvironment), nameof(CosmosTestEnvironment.IsNotLinuxEmulator))].