[Bug/Question] GetNearestMatchesAsync missing on IVectorStoreVectorCollection (Semantic Kernel v1.51.0 + Sqlite 1.51.0-preview + Google 1.52.0-alpha)

[roytarak]

Summary

I'm working on a C# service that uses Semantic Kernel’s SqliteVectorStore together with GoogleAIEmbeddingGenerator (models/embedding-001) to store and search embeddings.

I’m running into a compilation issue when attempting to call GetNearestMatchesAsync on a SqliteVectorStoreRecordCollection.

Environment Details

NuGet Package Versions (from dotnet list package):

Package	Version
Microsoft.SemanticKernel	1.51.0
Microsoft.SemanticKernel.Connectors.Sqlite	1.51.0-preview
Microsoft.SemanticKernel.Connectors.Google	1.52.0-alpha
Microsoft.Extensions.VectorData.Abstractions	9.0.0-preview.1.25229.1

Environment:

Windows Server 2022
.NET SDK 8.0.401
Visual Studio 2022

Minimal Reproducible Code:

using Microsoft.SemanticKernel.Connectors.Google;
using Microsoft.SemanticKernel.Connectors.Sqlite;
using Microsoft.Extensions.VectorData;
using Microsoft.Extensions.VectorData.Core;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace VectorSearchRepro
{
public class SqliteVectorRecord : IVectorStoreRecord
{
public string Id { get; set; } = string.Empty;
public string Text { get; set; } = string.Empty;
public ReadOnlyMemory Vector { get; set; }

    public ReadOnlyMemory<float> GetVector() => Vector;
    public void SetVector(ReadOnlyMemory<float> vector) => Vector = vector;
}

public class Program
{
    private static SqliteVectorStore _vectorStore;
    private static IVectorStoreVectorCollection<string, SqliteVectorRecord> _collection;
    private static GoogleAIEmbeddingGenerator _generator;

    public static async Task Main()
    {
        string dbPath = "semantic_vectors.db";
        string geminiApiKey = Environment.GetEnvironmentVariable("GEMINI_API_KEY");

#pragma warning disable SKEXP001
#pragma warning disable SKEXP0070
_generator = new GoogleAIEmbeddingGenerator(
modelId: "models/embedding-001",
apiKey: geminiApiKey);
#pragma warning restore SKEXP0070
#pragma warning restore SKEXP001

        _vectorStore = new SqliteVectorStore(dbPath);
        _collection = new SqliteVectorStoreRecordCollection<string, SqliteVectorRecord>(
            _vectorStore, "agreements");

        var chunks = new List<string> { "Confidentiality clause text." };

        var result = await _generator.GenerateAsync(chunks);
        var embedding = result.Data.First().Vector;

        var record = new SqliteVectorRecord
        {
            Id = "1",
            Text = chunks[0],
            Vector = embedding
        };

        await _collection.UpsertAsync(record);

        // ❌ Error here:
        var results = await _collection.GetNearestMatchesAsync(
            embedding.ToArray(), limit: 3);

        Console.WriteLine(results);
    }
}

}

Error Message: 'IVectorStoreVectorCollection<string, SqliteVectorRecord>' does not contain a definition for 'GetNearestMatchesAsync'
and no accessible extension method 'GetNearestMatchesAsync' accepting a first argument of type
'IVectorStoreVectorCollection<string, SqliteVectorRecord>' could be found
(are you missing a using directive or an assembly reference?)

What I’ve Tried

Added using Microsoft.Extensions.VectorData;
Added using Microsoft.Extensions.VectorData.Core;
Verified _collection type is SqliteVectorStoreRecordCollection<string, SqliteVectorRecord>
Checked Semantic Kernel and VectorData assemblies for extension methods
No overload or extension method for nearest neighbor search appears to exist

Question

In Semantic Kernel v1.51.0 (with VectorData 9.x):
Where has the GetNearestMatchesAsync method been moved?
Which interface or class now exposes nearest-neighbor vector search for SqliteVectorStore collections?
Is there a new API (e.g., IVectorSearchCollection, IVectorQueryExecutor) that replaces this method?
If the API was refactored between 1.51.0-preview and 1.52.0-alpha, could you please point to the relevant example or PR?

Goal

I simply want to:
Generate embeddings using GoogleAIEmbeddingGenerator (models/embedding-001)
Store them in a local SQLite vector store
Perform semantic similarity search (kNN)
using Semantic Kernel’s built-in vector connectors.

Expected Behavior
_collection.GetNearestMatchesAsync() should return the top-N semantically similar text records.

Actual Behavior
Compilation fails — the method is no longer defined on IVectorStoreVectorCollection.