Send empty vector index type on Weaviate 1.37.5

.github/workflows/main.yaml

@@ -132,7 +132,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        version: ["1.32.27", "1.33.18", "1.34.20", "1.35.16", "1.36.10", "1.37.2"]
+        version: ["1.32.27", "1.33.18", "1.34.20", "1.35.16", "1.36.10", "1.37.5-e0fe0d5.amd64"]
     uses: ./.github/workflows/test-on-weaviate-version.yml
     secrets: inherit
     with:

.github/workflows/test-on-weaviate-version.yml

@@ -55,7 +55,7 @@ jobs:
             echo "🏃 DRY-RUN MODE: Skipping actual unit tests"
             echo '<?xml version="1.0" encoding="utf-8"?><TestRun><ResultSummary outcome="Completed"><Counters total="91" executed="91" passed="91" failed="0" error="0" timeout="0" aborted="0" inconclusive="0" passedButRunAborted="0" notRunnable="0" notExecuted="0" disconnected="0" warning="0" completed="0" inProgress="0" pending="0" /></ResultSummary></TestRun>' > ./test-results/test-unit-${{ inputs.weaviate-version }}.trx
           else
-            WEAVIATE_VERSION=${{ inputs.weaviate-version }} dotnet test --no-restore \
+            dotnet test --no-restore \
               --filter "FullyQualifiedName~Unit" \
               --logger "trx;LogFileName=test-unit-${{ inputs.weaviate-version }}.trx" \
               --results-directory ./test-results

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Removed
+
+- **`ReplicationAsyncConfig.MaxWorkers` and `ReplicationAsyncConfig.AliveNodesCheckingFrequency`** — Both fields have been no-ops on the server since Weaviate 1.37.3 and are now removed from the user-facing model, the OpenAPI spec, and the generated DTO. Existing code that sets these properties will not compile after upgrading; no behavioral change results from the removal.
+
 ---
 
 ## [1.1.0] — 2026-05-11

ci/docker-compose-cluster.yml

@@ -20,6 +20,7 @@ services:
       DEFAULT_VECTORIZER_MODULE: text2vec-transformers
       ENABLE_MODULES: text2vec-transformers
       AUTOSCHEMA_ENABLED: 'false'
+      DEFAULT_VECTOR_INDEX: '${DEFAULT_VECTOR_INDEX:-hfresh}'
       REPLICA_MOVEMENT_ENABLED: 'true'
       TRANSFORMERS_INFERENCE_API: http://transformers:8080
 
@@ -54,6 +55,7 @@ services:
       DEFAULT_VECTORIZER_MODULE: text2vec-transformers
       ENABLE_MODULES: text2vec-transformers
       AUTOSCHEMA_ENABLED: 'false'
+      DEFAULT_VECTOR_INDEX: '${DEFAULT_VECTOR_INDEX:-hfresh}'
       REPLICA_MOVEMENT_ENABLED: 'true'
       TRANSFORMERS_INFERENCE_API: http://transformers:8080
 
@@ -88,6 +90,7 @@ services:
       DEFAULT_VECTORIZER_MODULE: text2vec-transformers
       ENABLE_MODULES: text2vec-transformers
       AUTOSCHEMA_ENABLED: 'false'
+      DEFAULT_VECTOR_INDEX: '${DEFAULT_VECTOR_INDEX:-hfresh}'
       REPLICA_MOVEMENT_ENABLED: 'true'
       TRANSFORMERS_INFERENCE_API: http://transformers:8080
 ...

ci/docker-compose-okta-cc.yml

@@ -22,5 +22,6 @@ services:
       AUTHENTICATION_OIDC_GROUPS_CLAIM: 'groups'
       AUTHORIZATION_ADMINLIST_ENABLED: 'true'
       AUTHORIZATION_ADMINLIST_USERS: '0oa7e9ipdkVZRUcxo5d7'
+      DEFAULT_VECTOR_INDEX: '${DEFAULT_VECTOR_INDEX:-hfresh}'
       DISABLE_TELEMETRY: 'true'
 ...

ci/docker-compose-okta-users.yml

@@ -22,6 +22,7 @@ services:
       AUTHENTICATION_OIDC_GROUPS_CLAIM: 'groups'
       AUTHORIZATION_ADMINLIST_ENABLED: 'true'
       AUTHORIZATION_ADMINLIST_USERS: 'test@test.de'
+      DEFAULT_VECTOR_INDEX: '${DEFAULT_VECTOR_INDEX:-hfresh}'
       AUTHENTICATION_OIDC_SCOPES: 'openid,email'
       DISABLE_TELEMETRY: 'true'
 ...

ci/docker-compose-rbac.yml

@@ -27,6 +27,7 @@ services:
       AUTHORIZATION_ENABLE_RBAC: "true"
       AUTHENTICATION_DB_USERS_ENABLED: "true"
       AUTHENTICATION_OIDC_ENABLED: 'true'
+      DEFAULT_VECTOR_INDEX: '${DEFAULT_VECTOR_INDEX:-hfresh}'
       AUTHENTICATION_OIDC_CLIENT_ID: 'Peuc12y02UA0eAED1dqSjE5HtGUrpBsx'
       AUTHENTICATION_OIDC_ISSUER: 'https://auth.weaviate.cloud/Peuc12y02UA0eAED1dqSjE5HtGUrpBsx'
       AUTHENTICATION_OIDC_USERNAME_CLAIM: 'email'

ci/docker-compose.yml

@@ -31,6 +31,7 @@ services:
       CLUSTER_HOSTNAME: "singlenode"
       AUTOSCHEMA_ENABLED: 'false'
       DISABLE_TELEMETRY: 'true'
+      DEFAULT_VECTOR_INDEX: '${DEFAULT_VECTOR_INDEX:-hfresh}'
       DISABLE_LAZY_LOAD_SHARDS: 'true'
       OBJECTS_TTL_DELETE_SCHEDULE: "@every 1m"
       GRPC_MAX_MESSAGE_SIZE: 100000000  # 100mb

ci/start_weaviate.sh

@@ -4,6 +4,7 @@ set -eou pipefail
 
 DEFAULT_VERSION="1.34.0"
 MIN_SUPPORTED="1.31.0"
+DEFAULT_VECTOR_INDEX_VALUE="hfresh"
 REQUESTED_VERSION="${1:-$DEFAULT_VERSION}"
 
 # Compare versions; ensure REQUESTED_VERSION >= MIN_SUPPORTED
@@ -13,6 +14,7 @@ if [[ $(printf '%s\n' "$MIN_SUPPORTED" "$REQUESTED_VERSION" | sort -V | head -n1
 fi
 
 export WEAVIATE_VERSION="$REQUESTED_VERSION"
+export DEFAULT_VECTOR_INDEX="${DEFAULT_VECTOR_INDEX:-$DEFAULT_VECTOR_INDEX_VALUE}"
 
 cd "$(dirname "${BASH_SOURCE[0]}")"
 

src/Weaviate.Client.Tests/Common/ServerVersions.cs

@@ -10,4 +10,12 @@ internal static class ServerVersions
     /// Tests will skip if the running server reports a lower version.
     /// </summary>
     public const string MinSupported = "1.32.0";
+
+    /// <summary>
+    /// First Weaviate server version that applies a server-side default for
+    /// <c>vectorIndexType</c> when the client omits it. On this version and later,
+    /// the C# client must leave an unset <c>VectorIndexType</c> empty rather than
+    /// injecting <c>"hnsw"</c>.
+    /// </summary>
+    public const string DefaultVectorIndexTypeServerSide = "1.37.5";
 }

src/Weaviate.Client.Tests/Integration/DefaultVectorIndexTypeIntegrationTests.cs

@@ -0,0 +1,88 @@
+using Weaviate.Client.Models;
+using Weaviate.Client.Tests.Common;
+
+namespace Weaviate.Client.Tests.Integration;
+
+/// <summary>
+/// End-to-end coverage for default vector index behavior across server versions.
+/// Assertions rely on the connected server version reported by the test client.
+/// </summary>
+[Collection("DefaultVectorIndexTypeIntegrationTests")]
+public sealed class DefaultVectorIndexTypeIntegrationTests : IntegrationTests
+{
+    private const string DefaultVectorIndexEnvVar = "DEFAULT_VECTOR_INDEX";
+    private const string DefaultVectorIndexFallback = "hfresh";
+    private static readonly Version ServerDefaultCutoff = Version.Parse(
+        ServerVersions.DefaultVectorIndexTypeServerSide
+    );
+
+    private string ExpectedDefaultIndexType()
+    {
+        Assert.NotNull(_weaviate.WeaviateVersion);
+
+        var defaultVectorIndex = Environment.GetEnvironmentVariable(DefaultVectorIndexEnvVar);
+        if (string.IsNullOrWhiteSpace(defaultVectorIndex))
+        {
+            defaultVectorIndex = DefaultVectorIndexFallback;
+        }
+
+        return _weaviate.WeaviateVersion! >= ServerDefaultCutoff
+            ? defaultVectorIndex
+            : VectorIndex.HNSW.TypeValue;
+    }
+
+    /// <summary>
+    /// Scenario A on the named-vector path: user omits <c>VectorIndexType</c>
+    /// when configuring a named vector.
+    /// <list type="bullet">
+    ///   <item>1.37.5+: server applies <c>DEFAULT_VECTOR_INDEX</c> from the
+    ///   host env var (default <see cref="DefaultVectorIndexFallback"/>).</item>
+    ///   <item>Older: client injects <c>"hnsw"</c> and server stores it.</item>
+    /// </list>
+    /// </summary>
+    [Fact]
+    public async Task NamedVector_NoIndexType_GetsServerOrInjectedDefault()
+    {
+        var create = new CollectionCreateParams
+        {
+            Name = MakeUniqueCollectionName(
+                nameof(NamedVector_NoIndexType_GetsServerOrInjectedDefault)
+            ),
+            Properties = [Property.Text("title")],
+            VectorConfig = Configure.Vector("default", v => v.SelfProvided(), index: null),
+        };
+
+        var collection = await CollectionFactory<object>(create);
+        var config = await collection.Config.Get(TestContext.Current.CancellationToken);
+        Assert.NotNull(config.VectorConfig);
+        Assert.True(config.VectorConfig.ContainsKey("default"));
+        Assert.Equal(ExpectedDefaultIndexType(), config.VectorConfig["default"].VectorIndexType);
+    }
+
+    /// <summary>
+    /// Scenario B on the named-vector path: user explicitly configures
+    /// <c>VectorIndex.Flat</c>. Must round-trip as <c>"flat"</c> on every
+    /// server version — the inject helper must never overwrite an explicit
+    /// value.
+    /// </summary>
+    [Fact]
+    public async Task NamedVector_ExplicitFlat_IsPreserved()
+    {
+        var create = new CollectionCreateParams
+        {
+            Name = MakeUniqueCollectionName(nameof(NamedVector_ExplicitFlat_IsPreserved)),
+            Properties = [Property.Text("title")],
+            VectorConfig = Configure.Vector(
+                "default",
+                v => v.SelfProvided(),
+                index: new VectorIndex.Flat()
+            ),
+        };
+
+        var collection = await CollectionFactory<object>(create);
+        var config = await collection.Config.Get(TestContext.Current.CancellationToken);
+        Assert.NotNull(config.VectorConfig);
+        Assert.True(config.VectorConfig.ContainsKey("default"));
+        Assert.Equal(VectorIndex.Flat.TypeValue, config.VectorConfig["default"].VectorIndexType);
+    }
+}

src/Weaviate.Client.Tests/Integration/TestCollections.cs

@@ -196,7 +196,7 @@ public async Task Test_Collections_Export()
             name: "MyOwnSuffix",
             description: "My own description too",
             properties: [Property.Text("Name")],
-            vectorConfig: Configure.Vector(v => v.SelfProvided())
+            vectorConfig: Configure.Vector(v => v.SelfProvided(), index: new VectorIndex.HNSW())
         );
 
         var export = await _weaviate.Collections.Export(
@@ -327,7 +327,8 @@ public async Task Test_Collections_Export_NonDefaultValues_Sharding()
             collectionNamePartSeparator: "",
             vectorConfig: Configure.Vector(
                 "nondefault",
-                v => v.Text2VecTransformers(vectorizeCollectionName: false)
+                v => v.Text2VecTransformers(vectorizeCollectionName: false),
+                index: new VectorIndex.HNSW()
             ),
             invertedIndexConfig: new()
             {
@@ -485,7 +486,8 @@ public async Task Test_Collections_Export_NonDefaultValues_MultiTenacy()
             collectionNamePartSeparator: "",
             vectorConfig: Configure.Vector(
                 "nondefault",
-                v => v.Text2VecTransformers(vectorizeCollectionName: false)
+                v => v.Text2VecTransformers(vectorizeCollectionName: false),
+                index: new VectorIndex.HNSW()
             ),
             multiTenancyConfig: new()
             {
@@ -736,7 +738,7 @@ public async Task Test_Collection_Config_Update()
         // Arrange
         var collection = await CollectionFactory(
             name: "TestCollectionUpdate",
-            vectorConfig: Configure.Vector(t => t.SelfProvided()),
+            vectorConfig: Configure.Vector(t => t.SelfProvided(), index: new VectorIndex.HNSW()),
             properties: [Property.Text("name"), Property.Int("age")],
             multiTenancyConfig: new()
             {

src/Weaviate.Client.Tests/Integration/TestMultiVector.cs

@@ -82,7 +82,7 @@ public async Task Test_Should_Get_Config_Of_Created_Collection()
             name: "TestMultiVectorCollectionConfig",
             vectorConfig: new[]
             {
-                Configure.Vector("regular", v => v.SelfProvided()),
+                Configure.Vector("regular", v => v.SelfProvided(), index: new VectorIndex.HNSW()),
                 Configure.MultiVector("colbert", v => v.SelfProvided()),
             }
         );

src/Weaviate.Client.Tests/Integration/TestServerSideBatch.cs

@@ -458,7 +458,7 @@ public async Task ServerSideBatch_InsertManyWithOptions_Success()
     /// <summary>
     /// Tests that InsertManyAsync returns proper UUIDs in handles
     /// </summary>
-    [Fact(Timeout = 10000)]
+    [Fact(Timeout = 30000)]
     public async Task ServerSideBatch_TaskHandleUuid_MatchesInserted()
     {
         // Arrange