WIP

metricflow/model/semantics/linkable_spec_resolver.py

@@ -823,7 +823,27 @@ def _get_joined_elements(self, measure_semantic_model: SemanticModel) -> Linkabl
         """Get the elements that can be generated by joining other models to the given model."""
         # Create single-hop elements
         join_paths = []
+        linkable_metrics_set = LinkableElementSet()
         for entity in measure_semantic_model.entities:
+            # Get LinkableMetrics. These can use fan-out join paths since they will be aggregated on the right side.
+            for semantic_model_for_metric_join in self._entity_to_semantic_model[entity.name]:
+                if semantic_model_for_metric_join.name == measure_semantic_model.name:
+                    continue
+                new_linkable_metrics_set = self.get_joinable_metrics_for_semantic_model(
+                    semantic_model=semantic_model_for_metric_join,
+                    using_join_path=SemanticModelJoinPath(
+                        (
+                            SemanticModelJoinPathElement(
+                                semantic_model_reference=semantic_model_for_metric_join.reference,
+                                join_on_entity=entity.reference,
+                            ),
+                        )
+                    ),
+                )
+                linkable_metrics_set = LinkableElementSet.merge_by_path_key(
+                    [linkable_metrics_set, new_linkable_metrics_set]
+                )
+            # Get all other linkable elements. These can only use join paths that won't fan out.
             semantic_models = self._get_semantic_models_joinable_to_entity(
                 left_semantic_model_reference=measure_semantic_model.reference,
                 entity_reference=entity.reference,
@@ -841,6 +861,7 @@ def _get_joined_elements(self, measure_semantic_model: SemanticModel) -> Linkabl
                         )
                     )
                 )
+
         single_hop_elements = LinkableElementSet.merge_by_path_key(
             [
                 self.create_linkable_element_set_from_join_path(
@@ -851,6 +872,8 @@ def _get_joined_elements(self, measure_semantic_model: SemanticModel) -> Linkabl
             ]
         )
 
+        # TODO: enable more hops for linkable metrics?
+
         # Create multi-hop elements. At each iteration, we generate the list of valid elements based on the current join
         # path, extend all paths to include the next valid semantic model, then repeat.
         multi_hop_elements = LinkableElementSet()
@@ -880,7 +903,7 @@ def _get_joined_elements(self, measure_semantic_model: SemanticModel) -> Linkabl
             )
             join_paths = new_join_paths
 
-        return LinkableElementSet.merge_by_path_key((single_hop_elements, multi_hop_elements))
+        return LinkableElementSet.merge_by_path_key((single_hop_elements, linkable_metrics_set, multi_hop_elements))
 
     def _get_linkable_element_set_for_measure(
         self,
@@ -1006,7 +1029,10 @@ def create_linkable_element_set_from_join_path(
         join_path: SemanticModelJoinPath,
         with_properties: FrozenSet[LinkableElementProperties],
     ) -> LinkableElementSet:
-        """Given the current path, generate the respective linkable elements from the last semantic model in the path."""
+        """Given the current path, generate the respective linkable elements from the last semantic model in the path.
+
+        Does not include LinkableMetrics.
+        """
         semantic_model = self._semantic_model_lookup.get_by_reference(join_path.last_semantic_model_reference)
         assert semantic_model
 
@@ -1042,7 +1068,6 @@ def create_linkable_element_set_from_join_path(
 
         for entity in semantic_model.entities:
             # Avoid creating "booking_id__booking_id"
-            # TODO: we are getting the above - figure out why
             if entity.reference != join_path.last_entity_link:
                 linkable_entities.append(
                     LinkableEntity(
@@ -1061,9 +1086,6 @@ def create_linkable_element_set_from_join_path(
             path_key_to_linkable_entities={
                 linkable_entity.path_key: (linkable_entity,) for linkable_entity in linkable_entities
             },
-            path_key_to_linkable_metrics=self.get_joinable_metrics_for_semantic_model(
-                semantic_model=semantic_model, using_join_path=join_path
-            ).path_key_to_linkable_metrics,
         )
 
     def get_joinable_metrics_for_entity(self, entity_reference: EntityReference) -> Set[MetricReference]:

tests/model/test_semantic_model_container.py

@@ -204,8 +204,6 @@ def test_get_agg_time_dimension_specs_for_measure(semantic_model_lookup: Semanti
 
 
 def test_linkable_metrics_for_measure(  # noqa: D103
-    request: FixtureRequest,
-    mf_test_configuration: MetricFlowTestConfiguration,
     metric_lookup: MetricLookup,
     semantic_model_lookup: SemanticModelLookup,
 ) -> None:
@@ -218,15 +216,13 @@ def test_linkable_metrics_for_measure(  # noqa: D103
         ).path_key_to_linkable_metrics.values()
         for linkable_metric in linkable_metric_tuple
     }
-    print("num::", len(actual_metrics))
 
     semantic_models = semantic_model_lookup.get_semantic_models_for_measure(measure_reference)
     assert len(semantic_models) == 1
     measure_semantic_model = semantic_models[0]
 
     already_seen = set()
 
-    # Check for all single-hop metrics
     expected_single_hop_metrics = [
         linkable_metric
         for linkable_metrics in metric_lookup._linkable_spec_resolver.get_joinable_metrics_for_semantic_model(
@@ -243,24 +239,24 @@ def test_linkable_metrics_for_measure(  # noqa: D103
 
     expected_multi_hop_metrics = []
     for entity in measure_semantic_model.entities:
-        next_semantic_models = metric_lookup._linkable_spec_resolver._get_semantic_models_joinable_to_entity(
-            left_semantic_model_reference=measure_semantic_model.reference, entity_reference=entity.reference
-        )
+        next_semantic_models = metric_lookup._linkable_spec_resolver._entity_to_semantic_model[entity.name]
         for next_semantic_model in next_semantic_models:
-            expected_multi_hop_metrics += [
-                linkable_metric
-                for linkable_metrics in metric_lookup._linkable_spec_resolver.get_joinable_metrics_for_semantic_model(
-                    semantic_model=next_semantic_model,
-                    using_join_path=SemanticModelJoinPath(
-                        (
-                            SemanticModelJoinPathElement(
-                                semantic_model_reference=next_semantic_model.reference, join_on_entity=entity.reference
-                            ),
-                        )
+            if next_semantic_model.name == measure_semantic_model.name:
+                continue
+            # TODO: use SemanticModelJoinPath.from_single_element when merged
+            join_path = SemanticModelJoinPath(
+                (
+                    SemanticModelJoinPathElement(
+                        semantic_model_reference=next_semantic_model.reference, join_on_entity=entity.reference
                     ),
-                ).path_key_to_linkable_metrics.values()
-                for linkable_metric in linkable_metrics
-            ]
+                )
+            )
+            for linkable_metrics in metric_lookup._linkable_spec_resolver.get_joinable_metrics_for_semantic_model(
+                semantic_model=next_semantic_model,
+                using_join_path=join_path,
+            ).path_key_to_linkable_metrics.values():
+                for linkable_metric in linkable_metrics:
+                    expected_multi_hop_metrics.append(linkable_metric)
 
     for expected_metric in expected_multi_hop_metrics:
         assert expected_metric in actual_metrics
@@ -269,5 +265,4 @@ def test_linkable_metrics_for_measure(  # noqa: D103
         actual_metrics.remove(expected_metric)
 
     # Check that we didn't return any unexpected linkable metrics.
-    # LinkableMetric(element_name='booking_value_sub_instant_add_10', join_by_semantic_model=SemanticModelReference(semantic_model_name='visits_source'), entity_links=(EntityReference(element_name='user'),), properties=frozenset({<LinkableElementProperties.JOINED: 'joined'>, <LinkableElementProperties.METRIC: 'metric'>}), join_path=(SemanticModelJoinPathElement(semantic_model_reference=SemanticModelReference(semantic_model_name='visits_source'), join_on_entity=EntityReference(element_name='user')),))
     assert len(actual_metrics) == 0, f"Didn't find linkable metrics: {actual_metrics}"