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An in-process vector store: named collections, held for the store's lifetime.

public sealed class LodestarVectorStore : VectorStore

Constructor — LodestarVectorStore(LodestarVectorStoreOptions options = null). Every collection the store hands out takes the same LodestarVectorStoreOptions; null takes the defaults. It throws nothing and opens nothing — there is no connection to make.

Example — a store, one collection, and the hybrid search the package exists for. The record type is declared once, and every example on these pages uses it:

using Microsoft.Extensions.VectorData;

sealed class Note
{
    [VectorStoreKey]
    public string Id { get; set; } = string.Empty;

    [VectorStoreData(IsFullTextIndexed = true)]
    public string Text { get; set; } = string.Empty;

    [VectorStoreVector(3)]
    public ReadOnlyMemory<float> Embedding { get; set; }
}

using Lodestar.Extensions.VectorData;
using Microsoft.Extensions.VectorData;

static async Task<string> FuseAsync()
{
    using var store = new LodestarVectorStore();
    VectorStoreCollection<string, Note> notes = store.GetCollection<string, Note>("notes");

    await notes.UpsertAsync([
        new Note { Id = "a", Text = "the cat sat on the mat", Embedding = new float[] { 1f, 0f, 0f } },
        new Note { Id = "b", Text = "the dog ran in the park", Embedding = new float[] { 0f, 1f, 0f } },
        new Note { Id = "c", Text = "an elephant crossed the river", Embedding = new float[] { 0f, 0f, 1f } },
    ]);

    var hybrid = (IKeywordHybridSearchable<Note>)notes;
    List<VectorSearchResult<Note>> hits = await hybrid
        .HybridSearchAsync(new float[] { 1f, 0f, 0f }, ["elephant"], 2)
        .ToListAsync();

    return string.Join(",", hits.Select(hit => hit.Record.Id));
}

string order = FuseAsync().GetAwaiter().GetResult();  // => c,a

The query vector points at a, the keyword matches only c, and the fused order is c then a — which neither ranking gives alone. ToListAsync is .NET 10's System.Linq.AsyncEnumerable; the GetAwaiter().GetResult() only lets a synchronous example drive an asynchronous one.

Remarks — a collection exists once something has ensured it or written to it, and that is what LodestarVectorStore.ListCollectionNamesAsync and LodestarVectorStore.CollectionExistsAsync report. LodestarVectorStore.GetCollection alone creates nothing, the way asking a database for a table object does not create the table.

One name is one collection for the store's lifetime. Asking for the same name again returns the same instance, and deleting a collection empties it without forgetting it — a later write to that instance makes it exist again.

Nothing is persisted. The records live in this process and are gone when it ends. EmbeddingIndex can save itself, and this store does not expose that: a durable store would have to decide how the records and the fitted vocabulary are serialized, and the abstraction asks for neither.

Disposing the store disposes every collection it handed out and forgets them. Dispose is the base class's, so it has no entry of its own here.

Thread safety — not safe for concurrent writes, which is true of every collection it holds.

Applies to — net10.0, netstandard2.0.

See also — LodestarVectorStoreCollection, LodestarVectorStoreOptions, the Python equivalence table.