Document aggregate queries and built-in function mapping

[Copilot]

EF Core lacked consolidated guidance for aggregate projections, composed aggregate inputs, and provider-specific top-level aggregates. Built-in database function mapping via IsBuiltIn was also undocumented.

• Aggregate queries
  • Document GroupBy projections with filtering, ordering, and distinct inputs.
  • Show the constant-group workaround for provider-specific top-level aggregates.
  • Note that aggregate UDF mapping is unsupported.

var standardDeviation = context.Posts
    .GroupBy(_ => 1)
    .Select(g => EF.Functions.StandardDeviationSample(g.Select(p => p.Rating)))
    .FirstOrDefault();

• Function mapping

  • Document fluent .IsBuiltIn() and [DbFunction(IsBuiltIn = true)] configuration.
  • Add a corresponding sample.

• Provider references

  • Link SQL Server and SQLite aggregate translation tables to the conceptual guidance.

• Fixes Document aggregate functions #4002
• Fixes Document new IsBuiltIn API and property on DbFunctionAttribute #2476

[Copilot]

Pull request overview

Documents aggregate query composition, top-level aggregate workarounds, and built-in database function mapping.

Changes:

• Adds aggregate query guidance and examples.
• Documents IsBuiltIn configuration with a sample.
• Cross-links SQL Server and SQLite provider references.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
samples/core/Querying/UserDefinedFunctionMapping/Model.cs	Adds built-in function mapping sample.
entity-framework/core/querying/user-defined-function-mapping.md	Documents fluent and attribute configuration.
entity-framework/core/querying/complex-query-operators.md	Adds aggregate query guidance.
entity-framework/core/providers/sqlite/functions.md	Links conceptual aggregate guidance.
entity-framework/core/providers/sql-server/functions.md	Links conceptual aggregate guidance.

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[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.

[cincuranet]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved in a4dc721 by merging main and reconciling the two IsBuiltIn sections in user-defined-function-mapping.md and Model.cs (fluent IsBuiltIn/attribute example kept alongside the new DbFunctionAttribute/store-type section).

[Copilot]

🟡 Changes recommended

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Review details

• Files reviewed: 5/5 changed files
• Comments generated: 1
• Review effort level: Balanced

[Copilot]

🔵 Needs a closer look

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

entity-framework/core/querying/complex-query-operators.md:132

• This example includes ordered aggregate inputs, a feature introduced in EF Core 11, but the conceptual page presents it without the required preview/version notice. Readers using EF Core 10 or earlier may therefore expect OrderedTitles to translate even though the provider tables mark ordered aggregation as EF Core 11. Add the preview note before introducing these composed forms.

Some aggregate functions allow their input to be composed. Depending on the provider, `Where` can filter the input, `OrderBy` can specify its ordering, and `Distinct` can remove duplicates. The following query illustrates these shapes:

• Files reviewed: 5/5 changed files
• Comments generated: 0 new
• Review effort level: Balanced