SQL Server 2025 support

[mario-mestrovic]

Hi!

Now that SQL Server 2025 has support for vector indexes (DiskANN) can we expect this to get added to this package?
In EF Core 10 we now have IsVectorProperty and IsVectorIndex, RRF and hybrid search for Cosmos DB out of preview. SQL Server supports the same, would be great this gets added here. And would be even greater this gets added to EF Core 10 (but I don't see any plans to do that digging througt efcore issues and pull requests.

Thoughts?

[roji]

@mario-mestrovic EF 10 already has full support for the new vector data type, and the functionality of this plugin (e.g. translation of the VECTOR_DISTANCE()) has been foldedd into the SQL Server provider, so you'll no longer need this plugin at all.

DiskANN has not yet GA'd, and the mechanics for using (VECTOR_SEARCH()) are still being worked out; this is currently not supported in EF. We'll introduce support for these as they stabilize.

[mario-mestrovic]

Ah, got it, but not 100% correct. dotnet/efcore#36383 is merged but not available yet (using preview 7).
I'm guessing it will become available in next preview together with this dotnet/efcore#36441 ?

Would also be great if EF worked out of the box with not just float[] but also ReadOnlyMemory<float>
That way we can use EF for migrations together with vector data abstractions library for SK.

They have a lot of examples like this:

public class MovieEmbedding
{
    [VectorStoreRecordKey]
    public int Id {get;set;}

    [VectorStoreRecordData] 
    public string Name {get;set;}

    [VectorStoreRecordData]
    public string Description {get;set;}

    [VectorStoreRecordVector(1536, DistanceFunction.CosineSimilarity)]
    public ReadOnlyMemory<float> DescriptionEmbedding {get;set;}
}

But Im aiming to use EF for migrations and still have the same model compatible with SK abstractions by stripping the attributes and doing something like this

var definitions = new VectorStoreCollectionDefinition
  {
      Properties = new List<VectorStoreProperty>
          {
              new VectorStoreKeyProperty(nameof(MovieEmbedding.Id), typeof(int)),
              new VectorStoreDataProperty(nameof(MovieEmbedding.Name), typeof(string)) { IsIndexed = true },
              new VectorStoreDataProperty(nameof(MovieEmbedding.Description), typeof(string)) { IsFullTextIndexed = true },
              new VectorStoreVectorProperty(nameof(MovieEmbedding.DescriptionEmbedding), typeof(float), dimensions: 1536) { DistanceFunction = DistanceFunction.CosineSimilarity, IndexKind = IndexKind.DiskAnn },
          }
  };

  var collection = vectorStore.GetCollection<int, MovieEmbedding>("MovieEmbeddings", definitions );
  collection.SearchAsync("search");

[roji]

Ah, got it, but not 100% correct. dotnet/efcore#36383 is merged but not available yet (using preview 7).
I'm guessing it will become available in next preview together with this dotnet/efcore#36441 ?

Yes, the work was only recently done and will appear in the next preview (in a month), rc.1. You can see this by looking at the label of the associated issue: #34659.

Would also be great if EF worked out of the box with not just float[] but also ReadOnlyMemory
That way we can use EF for migrations together with vector data abstractions library for SK.

First, note that Microsoft.Extensions.VectorData also supports float[] (you don't have to use ReadOnlyMemory<float>).

Second, EF's vector search support uses the new SQL Server vector data type, which is new; SqlClient supports it via a new SqlVector type, which is what the EF support requires, at least currently. On the Microsoft.Extensions.VectorData side the work will also need to be done to switch over to the new vector data type, since that's not yet support there - that's something I'll likely work on in the next couple of months.