Update _linkable_reference_index to use a normal dict

metricflow/model/semantics/semantic_model_lookup.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import logging
-from collections import defaultdict
 from copy import deepcopy
 from typing import Dict, List, Optional, Sequence, Set
 
@@ -59,7 +58,7 @@ def __init__(  # noqa: D
         self._measure_agg_time_dimension: Dict[MeasureReference, TimeDimensionReference] = {}
         self._measure_non_additive_dimension_specs: Dict[MeasureReference, NonAdditiveDimensionSpec] = {}
         self._dimension_index: Dict[DimensionReference, List[SemanticModel]] = {}
-        self._linkable_reference_index: Dict[LinkableElementReference, List[SemanticModel]] = defaultdict(list)
+        self._linkable_reference_index: Dict[LinkableElementReference, List[SemanticModel]] = {}
         self._entity_index: Dict[EntityReference, List[SemanticModel]] = {}
         self._semantic_model_names: Set[str] = set()
 
@@ -245,11 +244,10 @@ def _add_semantic_model(self, semantic_model: SemanticModel) -> None:
                 )
                 self._measure_non_additive_dimension_specs[measure.reference] = non_additive_dimension_spec
         for dim in semantic_model.dimensions:
-            self._linkable_reference_index[dim.reference].append(semantic_model)
-
             semantic_models_for_dimension = self._dimension_index.get(dim.reference, [])
             semantic_models_for_dimension.append(semantic_model)
             self._dimension_index[dim.reference] = semantic_models_for_dimension
+            self._linkable_reference_index[dim.reference] = semantic_models_for_dimension
 
             self._dimension_ref_to_spec[dim.time_dimension_reference or dim.reference] = (
                 TimeDimensionSpec.from_name(dim.name)
@@ -261,8 +259,8 @@ def _add_semantic_model(self, semantic_model: SemanticModel) -> None:
             semantic_models_for_entity = self._entity_index.get(entity.reference, [])
             semantic_models_for_entity.append(semantic_model)
             self._entity_index[entity.reference] = semantic_models_for_entity
+            self._linkable_reference_index[entity.reference] = semantic_models_for_entity
 
-            self._linkable_reference_index[entity.reference].append(semantic_model)
             self._entity_ref_to_spec[entity.reference] = EntitySpec.from_name(entity.name)
 
         self._semantic_model_reference_to_semantic_model[semantic_model.reference] = semantic_model