diff --git a/benchs/bench_fw/benchmark.py b/benchs/bench_fw/benchmark.py
index 1053f99388..8ca68c4cd8 100644
--- a/benchs/bench_fw/benchmark.py
+++ b/benchs/bench_fw/benchmark.py
@@ -208,9 +208,11 @@ def set_io(self, benchmark_io):
         self.io.distance_metric = self.distance_metric
         self.io.distance_metric_type = self.distance_metric_type
 
-    def get_index_desc(self, factory: str) -> Optional[IndexDescriptor]:
+    def get_index_desc(self, factory_or_codec: str) -> Optional[IndexDescriptor]:
         for desc in self.index_descs:
-            if desc.factory == factory:
+            if desc.factory == factory_or_codec:
+                return desc
+            if desc.codec_alias == factory_or_codec:
                 return desc
         return None
 
@@ -232,7 +234,7 @@ def range_search_reference(self, index, parameters, range_metric):
             parameters,
             radius=m_radius,
         )
-        flat = index.factory == "Flat"
+        flat = index.is_flat_index()
         (
             gt_radius,
             range_search_metric_function,
@@ -650,6 +652,7 @@ def benchmark(
                     f"Range index {index_desc.factory} has no radius_score"
                 )
             results["metrics"] = {}
+            self.build_index_wrapper(index_desc)
             for metric_key, range_metric in index_desc.range_metrics.items():
                 (
                     gt_radius,
diff --git a/benchs/bench_fw/descriptors.py b/benchs/bench_fw/descriptors.py
index f1dd7354c2..173b07ce16 100644
--- a/benchs/bench_fw/descriptors.py
+++ b/benchs/bench_fw/descriptors.py
@@ -20,6 +20,7 @@ class IndexDescriptor:
     # but not both at the same time.
     path: Optional[str] = None
     factory: Optional[str] = None
+    codec_alias: Optional[str] = None
     construction_params: Optional[List[Dict[str, int]]] = None
     search_params: Optional[Dict[str, int]] = None
     # range metric definitions
diff --git a/benchs/bench_fw/index.py b/benchs/bench_fw/index.py
index 14f2158e64..3deaa4afcf 100644
--- a/benchs/bench_fw/index.py
+++ b/benchs/bench_fw/index.py
@@ -495,7 +495,7 @@ def range_search(
         radius: Optional[float] = None,
     ):
         logger.info("range_search: begin")
-        if search_parameters is not None and search_parameters["snap"] == 1:
+        if search_parameters is not None and search_parameters.get("snap") == 1:
             query_vectors = self.snap(query_vectors)
         filename = (
             self.get_range_search_name(
@@ -776,6 +776,9 @@ def add_range_or_val(name, range):
             )
         return op
 
+    def is_flat_index(self):
+        return self.get_index_name().startswith("Flat")
+
 
 # IndexFromCodec, IndexFromQuantizer and IndexFromPreTransform
 # are used to wrap pre-trained Faiss indices (codecs)
@@ -807,6 +810,9 @@ def get_codec_name(self):
         name += Index.param_dict_list_to_name(self.construction_params)
         return name
 
+    def fetch_meta(self, dry_run=False):
+        return None, None
+
     def fetch_codec(self):
         codec = self.io.read_index(
             os.path.basename(self.path),
@@ -911,7 +917,7 @@ def fetch_codec(self, dry_run=False):
             assert codec_size is not None
             meta = {
                 "training_time": training_time,
-                "training_size": self.training_vectors.num_vectors,
+                "training_size": self.training_vectors.num_vectors if self.training_vectors else 0,
                 "codec_size": codec_size,
                 "sa_code_size": self.get_sa_code_size(codec),
                 "code_size": self.get_code_size(codec),