Add RQ4 centered quantization support

integration/test_collection_config.py

@@ -662,6 +662,46 @@ def test_hnsw_with_rq(collection_factory: CollectionFactory) -> None:
     assert config.vector_index_config.quantizer.rescore_limit == 20
 
 
+def test_hnsw_with_rq4c(collection_factory: CollectionFactory) -> None:
+    dummy = collection_factory("dummy")
+    if dummy._connection._weaviate_version.is_lower_than(1, 39, 2):
+        pytest.skip("RQ centering is not supported in Weaviate versions lower than 1.39.2")
+
+    collection = collection_factory(
+        vector_index_config=Configure.VectorIndex.hnsw(
+            vector_cache_max_objects=5,
+            quantizer=Configure.VectorIndex.Quantizer.rq(
+                bits=4, centering=True, rescore_limit=20, training_limit=5000
+            ),
+        ),
+    )
+
+    config = collection.config.get()
+    assert config.vector_index_type == VectorIndexType.HNSW
+    assert config.vector_index_config is not None
+    assert isinstance(config.vector_index_config, _VectorIndexConfigHNSW)
+    assert isinstance(config.vector_index_config.quantizer, _RQConfig)
+    assert config.vector_index_config.quantizer is not None
+    assert config.vector_index_config.quantizer.bits == 4
+    assert config.vector_index_config.quantizer.centering is True
+    assert config.vector_index_config.quantizer.rescore_limit == 20
+    assert config.vector_index_config.quantizer.training_limit == 5000
+
+    collection.config.update(
+        vector_index_config=Reconfigure.VectorIndex.hnsw(
+            quantizer=Reconfigure.VectorIndex.Quantizer.rq(rescore_limit=50, training_limit=10000),
+        ),
+    )
+
+    config = collection.config.get()
+    assert isinstance(config.vector_index_config, _VectorIndexConfigHNSW)
+    assert isinstance(config.vector_index_config.quantizer, _RQConfig)
+    assert config.vector_index_config.quantizer.bits == 4
+    assert config.vector_index_config.quantizer.centering is True
+    assert config.vector_index_config.quantizer.rescore_limit == 50
+    assert config.vector_index_config.quantizer.training_limit == 10000
+
+
 @pytest.mark.parametrize(
     "vector_index_config",
     [

test/collection/test_config.py

@@ -1619,6 +1619,23 @@ def test_vector_config_hnsw_rq() -> None:
     assert vi_dict["rq"]["rescoreLimit"] == 123
 
 
+def test_vector_config_hnsw_rq4c() -> None:
+    vector_index = Configure.VectorIndex.hnsw(
+        ef_construction=128,
+        quantizer=Configure.VectorIndex.Quantizer.rq(
+            bits=4, centering=True, rescore_limit=123, training_limit=5012
+        ),
+    )
+
+    vi_dict = vector_index._to_dict()
+
+    assert vi_dict["efConstruction"] == 128
+    assert vi_dict["rq"]["bits"] == 4
+    assert vi_dict["rq"]["centering"] is True
+    assert vi_dict["rq"]["rescoreLimit"] == 123
+    assert vi_dict["rq"]["trainingLimit"] == 5012
+
+
 def test_vector_config_flat_pq() -> None:
     vector_index = Configure.VectorIndex.flat(
         distance_metric=VectorDistances.DOT,

weaviate/collections/classes/config.py

@@ -1981,6 +1981,8 @@ class _RQConfig(_ConfigBase):
     cache: Optional[bool]
     bits: Optional[int]
     rescore_limit: int
+    centering: Optional[bool]
+    training_limit: Optional[int]
 
 
 BQConfig = _BQConfig
@@ -2984,6 +2986,8 @@ def rq(
         rescore_limit: Optional[int] = None,
         enabled: bool = True,
         bits: Optional[int] = None,
+        centering: Optional[bool] = None,
+        training_limit: Optional[int] = None,
     ) -> _RQConfigUpdate:
         """Create a `_RQConfigUpdate` object to be used when updating the Rotational quantization (RQ) configuration of Weaviate.
 
@@ -2992,7 +2996,13 @@ def rq(
         Arguments:
             See [the docs](https://weaviate.io/developers/weaviate/concepts/vector-index#hnsw-with-compression) for a more detailed view!
         """  # noqa: D417 (missing argument descriptions in the docstring)
-        return _RQConfigUpdate(enabled=enabled, rescoreLimit=rescore_limit, bits=bits)
+        return _RQConfigUpdate(
+            enabled=enabled,
+            rescoreLimit=rescore_limit,
+            bits=bits,
+            centering=centering,
+            trainingLimit=training_limit,
+        )
 
 
 class _VectorIndexUpdate:

weaviate/collections/classes/config_methods.py

@@ -157,6 +157,8 @@ def __get_quantizer_config(
             cache=config["rq"].get("cache"),
             bits=config["rq"].get("bits"),
             rescore_limit=config["rq"].get("rescoreLimit"),
+            centering=config["rq"].get("centering"),
+            training_limit=config["rq"].get("trainingLimit"),
         )
     return quantizer
 

weaviate/collections/classes/config_vector_index.py

@@ -299,6 +299,8 @@ class _RQConfigCreate(_QuantizerConfigCreate):
     cache: Optional[bool]
     bits: Optional[int]
     rescoreLimit: Optional[int]
+    centering: Optional[bool]
+    trainingLimit: Optional[int]
 
     @staticmethod
     def quantizer_name() -> str:
@@ -337,6 +339,8 @@ class _RQConfigUpdate(_QuantizerConfigUpdate):
     enabled: Optional[bool]
     rescoreLimit: Optional[int]
     bits: Optional[int]
+    centering: Optional[bool]
+    trainingLimit: Optional[int]
 
     @staticmethod
     def quantizer_name() -> str:
@@ -486,6 +490,8 @@ def rq(
         cache: Optional[bool] = None,
         bits: Optional[int] = None,
         rescore_limit: Optional[int] = None,
+        centering: Optional[bool] = None,
+        training_limit: Optional[int] = None,
     ) -> _RQConfigCreate:
         """Create a `_RQConfigCreate` object to be used when defining the Rotational quantization (RQ) configuration of Weaviate.
 
@@ -498,6 +504,8 @@ def rq(
             cache=cache,
             bits=bits,
             rescoreLimit=rescore_limit,
+            centering=centering,
+            trainingLimit=training_limit,
         )
 
     @staticmethod