Implement support for SQL Server vector indexes by roji · Pull Request #37538 · dotnet/efcore

roji · 2026-01-19T22:59:07Z

roji · 2026-01-20T06:13:51Z

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azure-pipelines · 2026-01-20T06:14:02Z

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Copilot

Pull request overview

This pull request implements support for SQL Server vector indexes, a preview feature in SQL Server 2025. The implementation includes model building APIs, migration generation, scaffolding/reverse engineering support, and validation.

Changes:

Added fluent API for creating vector indexes via HasVectorIndex() extension methods with configurable metrics (cosine, euclidean, dot) and index types (DiskANN)
Implemented migration SQL generation for CREATE VECTOR INDEX and DROP INDEX statements with proper formatting
Added scaffolding support to reverse-engineer vector indexes from existing databases via sys.vector_indexes system view
Added model validation to ensure vector indexes have exactly one column
Updated test utilities to properly manage connection state during test execution

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
`src/EFCore.SqlServer/Extensions/SqlServerEntityTypeBuilderExtensions.cs`	Added `HasVectorIndex()` methods for typed and untyped entity builders
`src/EFCore.SqlServer/Extensions/SqlServerIndexExtensions.cs`	Added extension methods for getting/setting vector index metric and type annotations
`src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder.cs`	New builder class for configuring vector index properties (non-generic)
`src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder`1.cs`	New builder class for configuring vector index properties (generic)
`src/EFCore.SqlServer/Metadata/Internal/SqlServerAnnotationNames.cs`	Added annotation constants for VectorIndexMetric and VectorIndexType
`src/EFCore.SqlServer/Metadata/Internal/SqlServerAnnotationProvider.cs`	Added logic to provide vector index annotations for table indexes
`src/EFCore.SqlServer/Infrastructure/Internal/SqlServerModelValidator.cs`	Added validation to ensure vector indexes have single column
`src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs`	Implemented SQL generation for CREATE VECTOR INDEX with metric and type options
`src/EFCore.SqlServer/Scaffolding/Internal/SqlServerDatabaseModelFactory.cs`	Added GetVectorIndexes method to scaffold vector indexes from database, excluded vector indexes from regular index query
`src/EFCore.SqlServer/Properties/SqlServerStrings.resx`	Added error message for vector index single column requirement
`src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs`	Generated code for new error message
`test/EFCore.SqlServer.FunctionalTests/Migrations/MigrationsSqlServerTest.cs`	Added tests for creating and dropping vector indexes with different configurations
`test/EFCore.SqlServer.FunctionalTests/TestUtilities/SqlServerTestStore.cs`	Fixed connection state management to restore original state after command execution

Files not reviewed (1)

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Language not supported

src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder.cs

src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder`1.cs

src/EFCore.SqlServer/Extensions/SqlServerEntityTypeBuilderExtensions.cs

src/EFCore.SqlServer/Scaffolding/Internal/SqlServerDatabaseModelFactory.cs

test/EFCore.SqlServer.FunctionalTests/Migrations/MigrationsSqlServerTest.cs

src/EFCore.SqlServer/Infrastructure/Internal/SqlServerModelValidator.cs

Copilot

Pull request overview

Copilot reviewed 14 out of 15 changed files in this pull request and generated 2 comments.

Files not reviewed (1)

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Language not supported

src/EFCore.SqlServer/Scaffolding/Internal/SqlServerDatabaseModelFactory.cs

src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder`1.cs

roji · 2026-01-20T06:23:50Z

src/EFCore.SqlServer/Extensions/SqlServerEntityTypeBuilderExtensions.cs

+    /// </param>
+    /// <param name="name">The name to assign to the index.</param>
+    /// <returns>A builder to further configure the vector index.</returns>
+    public static VectorIndexBuilder<TEntity> HasVectorIndex<TEntity>(


@AndriySvyryd take a look at this builder/metadata proposal, and feel free to push any changes directly to the PR. Some notes:

Defining a distance metric (cosine, euclidean...) is mandatory, so I'm using that as the metadata indication that an index is a vector index.

Vector indexes aren't just some extra facets on regular indexes - they're a completely different type of index (the options when creating a vector index are very different from those of regular indexes). As a result, I'm proposing that we have a separate VectorIndexBuilder to only expose the relevant APIs, even if metadata-wise it's just an index.

Interestingly the SQL Server sys.vector_indexes table that's used to scaffold inherits sys.indexes, as if vector indexes are an extension to regular indexes; but their creation syntax is very different. In any case, we can change this in the future, making VectorIndexBuilder extend IndexBuilder if we really want to.

Copilot

Pull request overview

Copilot reviewed 14 out of 15 changed files in this pull request and generated 5 comments.

Files not reviewed (1)

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Language not supported

src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder.cs

src/EFCore.SqlServer/Extensions/SqlServerEntityTypeBuilderExtensions.cs

src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder`1.cs

src/EFCore.SqlServer/Extensions/SqlServerEntityTypeBuilderExtensions.cs

src/EFCore.SqlServer/Scaffolding/Internal/SqlServerDatabaseModelFactory.cs

Copilot

Pull request overview

Copilot reviewed 14 out of 15 changed files in this pull request and generated 3 comments.

Files not reviewed (1)

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Language not supported

src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder.cs

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

src/EFCore.SqlServer/Metadata/Builders/VectorIndexBuilder`1.cs

Copilot

Pull request overview

Copilot reviewed 14 out of 15 changed files in this pull request and generated no new comments.

Files not reviewed (1)

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Language not supported

roji · 2026-01-22T07:16:23Z

/azp run

azure-pipelines · 2026-01-22T07:16:35Z

Azure Pipelines successfully started running 1 pipeline(s).

Copilot

Pull request overview

Copilot reviewed 13 out of 14 changed files in this pull request and generated 3 comments.

Files not reviewed (1)

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Language not supported

src/EFCore.SqlServer/Extensions/SqlServerEntityTypeBuilderExtensions.cs

test/EFCore.SqlServer.FunctionalTests/TestUtilities/SqlServerTestStore.cs

roji · 2026-02-04T20:19:43Z

@AndriySvyryd ready for re-review. Check especially the last commit with the added tests (fully AI-generated).

AndriySvyryd · 2026-02-04T20:45:55Z

src/EFCore.SqlServer/Infrastructure/Internal/SqlServerModelValidator.cs

+                if (index.GetVectorMetric() is null or "")
+                {
+                    throw new InvalidOperationException(
+                        SqlServerStrings.VectorIndexRequiresMetric(
+                            index.DisplayName(),
+                            index.DeclaringEntityType.DisplayName()));
+                }
+
+                if (index.GetVectorIndexType() is "")
+                {
+                    throw new InvalidOperationException(
+                        SqlServerStrings.VectorIndexRequiresType(
+                            index.DisplayName(),
+                            index.DeclaringEntityType.DisplayName()));
+                }


Add tests for these

AndriySvyryd · 2026-02-04T20:47:51Z

test/EFCore.SqlServer.FunctionalTests/ModelBuilding/SqlServerModelBuilderTestBase.cs

+            {
+                b.Property(e => e.Vector).HasColumnType("vector(3)");
+
+                if (b is IInfrastructure<EntityTypeBuilder<VectorIndexEntity>> genericBuilder)


Don't cast to IInfrastructure here, add extension methods that mimic the new fluent API

AndriySvyryd · 2026-02-04T20:51:14Z

....SqlServer.FunctionalTests/Scaffolding/Baselines/Vector_index/VectorIndexEntityEntityType.cs

+            index.AddAnnotation("SqlServer:VectorIndexMetric", "cosine");
+            index.AddAnnotation("SqlServer:VectorIndexType", "DiskANN");


These are not used at runtime, so they should be filtered out in SqlServerCSharpRuntimeAnnotationCodeGenerator

Am noting that if we do implement a unified vector search API, we'd likely need at least the similarity measure at runtime. But we'll cross that bridge when we get to it.

(mostly AI-generated)

roji · 2026-02-04T23:20:49Z

@AndriySvyryd you comments should be addressed - mainly by AI.

I suggest that for these things, which are in your area and where you know exactly what you want, it's probably better for you to push changes directly into the PR rather than ask - just faster/easier with less roundtrips.

Copilot

Pull request overview

Copilot reviewed 22 out of 23 changed files in this pull request and generated 1 comment.

Files not reviewed (1)

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Language not supported

Copilot · 2026-02-04T23:29:56Z

test/EFCore.SqlServer.FunctionalTests/Migrations/MigrationsSqlServerTest.cs

+
+                Assert.Same(table.Columns.Single(c => c.Name == "Vector"), indexColumn);
+                Assert.Equal("COSINE", index[SqlServerAnnotationNames.VectorIndexMetric]);
+                Assert.Equal("DiskANN", index[SqlServerAnnotationNames.VectorIndexType]);


The test expects VectorIndexType to be "DiskANN" even though UseType() was never called. This assertion assumes that SQL Server defaults vector indexes to type "DiskANN" when the TYPE clause is omitted. While this may be correct based on SQL Server's behavior, it should be verified that SQL Server actually provides this default. If SQL Server does not default to "DiskANN", this assertion will fail.

Suggested change

Assert.Equal("DiskANN", index[SqlServerAnnotationNames.VectorIndexType]);

AndriySvyryd · 2026-02-05T01:39:12Z

I suggest that for these things, which are in your area and where you know exactly what you want, it's probably better for you to push changes directly into the PR rather than ask - just faster/easier with less roundtrips.

That's not how this works, if you submit a PR you are signing up as a Copilot copy-paster 😆

Hopefully, CCA will be able to work on fork PRs soon.

roji · 2026-02-05T07:29:28Z

That's not how this works, if you submit a PR you are signing up as a Copilot copy-paster 😆

Yeah I'm aware :)

Jokes aside, it's less that I care about Copilot copy-pasting, more about whether the results coming out of Copilot will be exactly what you want...

See dotnet/efcore#37536 See dotnet/efcore#37538 See dotnet/efcore#37578

roji force-pushed the SqlServerVectorIndex branch from 6e92827 to ff9db2e Compare January 19, 2026 23:27

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roji force-pushed the SqlServerVectorIndex branch from 936b8d4 to 5232b11 Compare January 20, 2026 09:23

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roji added 2 commits February 4, 2026 21:07

Address review comments

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Add tests

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roji force-pushed the SqlServerVectorIndex branch from 33d481b to ef783e4 Compare February 4, 2026 20:19

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roji added 2 commits February 5, 2026 00:03

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(mostly AI-generated)

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roji merged commit e72cb67 into dotnet:main Feb 5, 2026
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roji deleted the SqlServerVectorIndex branch February 5, 2026 01:43

roji added a commit to roji/EntityFramework.Docs that referenced this pull request Feb 5, 2026

Document new SQL Server vector and full-text search features

fb9ba6b

See dotnet/efcore#37536 See dotnet/efcore#37538 See dotnet/efcore#37578

roji mentioned this pull request Feb 5, 2026

Document new SQL Server vector and full-text search features dotnet/EntityFramework.Docs#5258

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roji added a commit to roji/EntityFramework.Docs that referenced this pull request Feb 5, 2026

Document new SQL Server vector and full-text search features

bf61efe

See dotnet/efcore#37536 See dotnet/efcore#37538 See dotnet/efcore#37578

roji added a commit to roji/EntityFramework.Docs that referenced this pull request Feb 5, 2026

Document new SQL Server vector and full-text search features

41f8813

See dotnet/efcore#37536 See dotnet/efcore#37538 See dotnet/efcore#37578

dotnet-maestro bot mentioned this pull request Feb 6, 2026

[main] Source code updates from dotnet/efcore dotnet/dotnet#4676

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roji added a commit to dotnet/EntityFramework.Docs that referenced this pull request Feb 7, 2026

Document new SQL Server vector and full-text search features (#5258)

453bf75

See dotnet/efcore#37536 See dotnet/efcore#37538 See dotnet/efcore#37578

		index.AddAnnotation("SqlServer:VectorIndexMetric", "cosine");
		index.AddAnnotation("SqlServer:VectorIndexType", "DiskANN");

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roji Jan 20, 2026 •

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