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Vectors

Insert, search, query, and delete vectors in a Milvus collection.

This example assumes using Milvus; is in scope and apiKey contains your Milvus API key.

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var client = Client;
var collectionName = $"test_vectors_{Guid.NewGuid():N}";

// Create a collection with 4-dimensional vectors using Cosine distance.

await client.CollectionOperationsV2.CreateVectordbCollectionsCreateAsync(
    requestTimeout: 30,
    collectionName: collectionName,
    dimension: 4,
    metricType: "COSINE",
    autoId: false,
    primaryFieldName: "id",
    vectorFieldName: "vector");

// Insert vectors with associated data into the collection.
// Note: Row-based insert with mixed types (int, float[]) requires raw JSON
// because the source-generated serializer cannot handle polymorphic object arrays.

using var insertHttpResponse = await client.HttpClient.PostAsJsonAsync(
    "/v2/vectordb/entities/insert",
    new
    {
        collectionName,
        data = new[]
        {
            new { id = 1, vector = new[] { 0.05f, 0.61f, 0.76f, 0.74f } },
            new { id = 2, vector = new[] { 0.19f, 0.81f, 0.75f, 0.11f } },
            new { id = 3, vector = new[] { 0.36f, 0.55f, 0.47f, 0.94f } },
            new { id = 4, vector = new[] { 0.18f, 0.01f, 0.85f, 0.80f } },
            new { id = 5, vector = new[] { 0.24f, 0.18f, 0.22f, 0.44f } },
        },
    });
insertHttpResponse.EnsureSuccessStatusCode();
var insertJson = JsonDocument.Parse(await insertHttpResponse.Content.ReadAsStringAsync());
var insertCode = insertJson.RootElement.GetProperty("code").GetInt32();
var insertCount = insertJson.RootElement.GetProperty("data").GetProperty("insertCount").GetInt32();

Console.WriteLine($"Inserted {insertCount} vectors.");

// Search for the 3 nearest neighbors using a query vector.
// Note: Milvus v2.5+ uses "data" field for search vectors (v2.4 used "vector").

using var searchHttpResponse = await client.HttpClient.PostAsJsonAsync(
    "/v2/vectordb/entities/search",
    new
    {
        collectionName,
        data = new[] { new[] { 0.2f, 0.1f, 0.9f, 0.7f } },
        limit = 3,
        outputFields = new[] { "id" },
    });
searchHttpResponse.EnsureSuccessStatusCode();
var searchJson = JsonDocument.Parse(await searchHttpResponse.Content.ReadAsStringAsync());
var searchCode = searchJson.RootElement.GetProperty("code").GetInt32();
var searchData = searchJson.RootElement.GetProperty("data");

Console.WriteLine($"Search returned {searchData.GetArrayLength()} results.");

// Query entities by filter expression.

var queryResponse = await client.VectorOperationsV2.CreateVectordbEntitiesQueryAsync(
    collectionName: collectionName,
    filter: "id in [1, 2, 3]",
    outputFields: ["id"]);

Console.WriteLine($"Query returned {queryResponse.Data!.Count} entities.");

// Delete specific entities by filter.

var deleteResponse = await client.VectorOperationsV2.CreateVectordbEntitiesDeleteAsync(
    collectionName: collectionName,
    filter: "id in [1, 2]");

Console.WriteLine("Deleted entities with id in [1, 2].");

// Wait for delete to propagate (Milvus deletes are eventually consistent).

await Task.Delay(TimeSpan.FromSeconds(2));

// Verify the remaining entity count.

var queryAfterDelete = await client.VectorOperationsV2.CreateVectordbEntitiesQueryAsync(
    collectionName: collectionName,
    filter: "id >= 0",
    outputFields: ["id"]);

Console.WriteLine($"Remaining entities: {queryAfterDelete.Data!.Count}");

// Cleanup: drop the collection.

await client.CollectionOperationsV2.CreateVectordbCollectionsDropAsync(
    collectionName1: collectionName);