ChromaDotNet.VectorData 0.1.2

ChromaDotNet.VectorData

Chroma provider for Microsoft.Extensions.VectorData, built on ChromaDotNet.Client.

This is a community project. It is not affiliated with or endorsed by Chroma.

Quick start

1. Run Chroma with Docker:

docker run -d --name chroma -p 8000:8000 chromadb/chroma

2. Install the NuGet package:

dotnet add package ChromaDotNet.VectorData

3. Store and search records:

using ChromaDB.Client;
using ChromaDB.VectorData;
using Microsoft.Extensions.VectorData;

using var httpClient = new HttpClient();
using var vectorStore = new ChromaVectorStore(new ChromaClient(new ChromaConfigurationOptions("http://localhost:8000"), httpClient));

var collection = vectorStore.GetCollection<string, Hotel>("hotels");
await collection.EnsureCollectionExistsAsync();

await collection.UpsertAsync(new Hotel { Id = "h1", Name = "Grand", Rating = 5, Embedding = new float[] { 0.1f, 0.2f, 0.3f, 0.4f } });

await foreach (var result in collection.SearchAsync(new float[] { 0.1f, 0.2f, 0.3f, 0.4f }, top: 3, new() { Filter = h => h.Rating >= 4 }))
{
    Console.WriteLine($"{result.Record.Name}: {result.Score}");
}

public sealed class Hotel
{
    [VectorStoreKey]
    public string Id { get; set; } = "";

    [VectorStoreData]
    public string? Name { get; set; }

    [VectorStoreData]
    public int Rating { get; set; }

    [VectorStoreVector(4)]
    public ReadOnlyMemory<float> Embedding { get; set; }
}

With dependency injection, the vector store takes the ChromaClient of the container, like the singleton that ChromaDotNet.Client.DependencyInjection registers with an HttpClient from IHttpClientFactory:

services.AddChromaClient(_ => new ChromaConfigurationOptions("http://localhost:8000"));
services.AddChromaVectorStore();

Or it creates its own client:

services.AddChromaVectorStore("http://localhost:8000");

Supported

• Keys: string and Guid.
• One vector per record: ReadOnlyMemory<float>, Embedding<float> or float[], or any type with an embedding generator.
• Data properties: string, int, long, double, float, bool, DateTime, DateTimeOffset, DateOnly, and arrays or lists of these, stored as Chroma metadata; dates are stored as ISO 8601 strings.
• Distance functions: CosineSimilarity (the default), CosineDistance, DotProductSimilarity, NegativeDotProductSimilarity, EuclideanDistance and EuclideanSquaredDistance, with the HNSW index.
• An existing collection must use the space of the distance function, as a collection created by another Chroma client without a space uses l2: otherwise the provider throws, rather than turning the distances of another space into scores.
• Filters: == and !=, <, <=, > and >= on numbers, &&, ||, !, Contains over an inline list or an array property, and Any with Contains over an inline list.
• Filters on the key: == and Contains over a list of keys, joined to the other conditions with &&; Chroma looks the records up by id.
• NativeAOT and trimming: the dynamic collection, from GetDynamicCollection with a VectorStoreCollectionDefinition, works without reflection; ChromaCollection<TKey, TRecord> maps the properties of the record type by reflection.

Limitations

• Chroma metadata has no null values: a null property is not stored, and filtering on null is not supported.
• Chroma does not store empty lists: an empty array or list is not stored, and comes back as null.
• GetAsync with a filter does not support ordering.
• Comparisons work on numbers only.
• Array properties need Chroma 1.5.0 or later.
• Hybrid search is not supported, so IsFullTextIndexed is accepted and has no effect.

The provider runs the Microsoft.Extensions.VectorData conformance tests against Chroma 1.5.0, 1.5.9 and the latest release, and passes them on Chroma Cloud.