feat(milvus): add nprobe parameter for SCANN index

- Add nprobe search parameter for SCANN index (default: 64)
- Enable nprobe UI configuration for SCANN_MILVUS index type

Signed-off-by: JackLCL <chenglong.li@zilliz.com>

Author: JackLCL

vectordb_bench/backend/clients/milvus/config.py

@@ -417,6 +417,7 @@ def search_param(self) -> dict:
 class SCANNConfig(MilvusIndexConfig, DBCaseConfig):
     nlist: int = 1024
     with_raw_data: bool = False
+    nprobe: int = 64
     reorder_k: int | None = 100
     index: IndexType = IndexType.SCANN_MILVUS
 
@@ -433,7 +434,10 @@ def index_param(self) -> dict:
     def search_param(self) -> dict:
         return {
             "metric_type": self.parse_metric(),
-            "params": {"reorder_k": self.reorder_k},
+            "params": {
+                "nprobe": self.nprobe,
+                "reorder_k": self.reorder_k,
+            },
         }
 
 

vectordb_bench/frontend/config/dbCaseConfigs.py

@@ -1056,6 +1056,7 @@ class CaseConfigInput(BaseModel):
         IndexType.IVFPQ.value,
         IndexType.IVFSQ8.value,
         IndexType.IVF_RABITQ.value,
+        IndexType.SCANN_MILVUS.value,
         IndexType.GPU_IVF_FLAT.value,
         IndexType.GPU_IVF_PQ.value,
         IndexType.GPU_BRUTE_FORCE.value,