Bug fix: apply offset for nested derived metrics

metricflow/dataflow/builder/dataflow_plan_builder.py

@@ -217,7 +217,7 @@ def _build_derived_metric_output_node(
         queried_linkable_specs: LinkableSpecSet,
         where_constraint: Optional[WhereFilterSpec] = None,
         time_range_constraint: Optional[TimeRangeConstraint] = None,
-    ) -> ComputeMetricsNode:
+    ) -> BaseOutput:
         """Builds a node to compute a metric defined from other metrics."""
         metric = self._metric_lookup.get_metric(metric_spec.reference)
         metric_input_specs = self._metric_lookup.metric_input_specs_for_metric(
@@ -232,15 +232,6 @@ def _build_derived_metric_output_node(
         parent_nodes: List[BaseOutput] = []
 
         for metric_input_spec in metric_input_specs:
-            # TODO: See: https://github.com/dbt-labs/metricflow/issues/881
-            if (metric_spec.offset_to_grain is not None or metric_spec.offset_to_grain is not None) and (
-                metric_input_spec.offset_window is not None or metric_input_spec.offset_to_grain is not None
-            ):
-                raise NotImplementedError(
-                    f"Multiple descendent metrics in a derived metric hierarchy are not yet supported. "
-                    f"For {metric_spec}, the parent metric input is {metric_input_spec}"
-                )
-
             parent_nodes.append(
                 self._build_any_metric_output_node(
                     metric_spec=MetricSpec(
@@ -256,24 +247,34 @@ def _build_derived_metric_output_node(
                 )
             )
 
-        if len(parent_nodes) == 1:
-            return ComputeMetricsNode(
-                parent_node=parent_nodes[0],
-                metric_specs=[metric_spec],
-            )
-
-        return ComputeMetricsNode(
-            parent_node=CombineMetricsNode(parent_nodes=parent_nodes),
+        compute_metrics_node = ComputeMetricsNode(
+            parent_node=parent_nodes[0] if len(parent_nodes) == 1 else CombineMetricsNode(parent_nodes=parent_nodes),
             metric_specs=[metric_spec],
         )
 
+        # For nested ratio / derived metrics with time offset, apply offset after metric computation.
+        join_to_time_spine_node: Optional[JoinToTimeSpineNode] = None
+        if metric_spec.offset_window or metric_spec.offset_to_grain:
+            assert (
+                queried_linkable_specs.contains_metric_time
+            ), "Joining to time spine requires querying with metric_time."
+            join_to_time_spine_node = JoinToTimeSpineNode(
+                parent_node=compute_metrics_node,
+                requested_metric_time_dimension_specs=list(queried_linkable_specs.metric_time_specs),
+                time_range_constraint=time_range_constraint,
+                offset_window=metric_spec.offset_window,
+                offset_to_grain=metric_spec.offset_to_grain,
+                join_type=SqlJoinType.INNER,
+            )
+        return join_to_time_spine_node or compute_metrics_node
+
     def _build_any_metric_output_node(
         self,
         metric_spec: MetricSpec,
         queried_linkable_specs: LinkableSpecSet,
         where_constraint: Optional[WhereFilterSpec] = None,
         time_range_constraint: Optional[TimeRangeConstraint] = None,
-    ) -> ComputeMetricsNode:
+    ) -> BaseOutput:
         """Builds a node to compute a metric of any type."""
         metric = self._metric_lookup.get_metric(metric_spec.reference)
 

metricflow/dataflow/dataflow_plan.py

@@ -650,7 +650,7 @@ def __init__(
         time_range_constraint: Optional[TimeRangeConstraint] = None,
         offset_window: Optional[MetricTimeWindow] = None,
         offset_to_grain: Optional[TimeGranularity] = None,
-    ) -> None:  # noqa: D
+    ) -> None:
         """Constructor.
 
         Args:
@@ -679,27 +679,27 @@ def id_prefix(cls) -> str:  # noqa: D
         return DATAFLOW_NODE_JOIN_TO_TIME_SPINE_ID_PREFIX
 
     @property
-    def requested_metric_time_dimension_specs(self) -> List[TimeDimensionSpec]:  # noqa: D
+    def requested_metric_time_dimension_specs(self) -> List[TimeDimensionSpec]:
         """Time dimension specs to use when creating time spine table."""
         return self._requested_metric_time_dimension_specs
 
     @property
-    def time_range_constraint(self) -> Optional[TimeRangeConstraint]:  # noqa: D
+    def time_range_constraint(self) -> Optional[TimeRangeConstraint]:
         """Time range constraint to apply when querying time spine table."""
         return self._time_range_constraint
 
     @property
-    def offset_window(self) -> Optional[MetricTimeWindow]:  # noqa: D
+    def offset_window(self) -> Optional[MetricTimeWindow]:
         """Time range constraint to apply when querying time spine table."""
         return self._offset_window
 
     @property
-    def offset_to_grain(self) -> Optional[TimeGranularity]:  # noqa: D
+    def offset_to_grain(self) -> Optional[TimeGranularity]:
         """Time range constraint to apply when querying time spine table."""
         return self._offset_to_grain
 
     @property
-    def join_type(self) -> SqlJoinType:  # noqa: D
+    def join_type(self) -> SqlJoinType:
         """Join type to use when joining to time spine."""
         return self._join_type
 

metricflow/test/dataflow/builder/test_dataflow_plan_builder.py

@@ -972,3 +972,29 @@ def test_dont_join_to_time_spine_if_no_time_dimension_requested(  # noqa: D
         mf_test_session_state=mf_test_session_state,
         dag_graph=dataflow_plan,
     )
+
+
+def test_nested_derived_metric_with_outer_offset(  # noqa: D
+    request: FixtureRequest,
+    mf_test_session_state: MetricFlowTestSessionState,
+    dataflow_plan_builder: DataflowPlanBuilder,
+) -> None:
+    dataflow_plan = dataflow_plan_builder.build_plan(
+        MetricFlowQuerySpec(
+            metric_specs=(MetricSpec(element_name="bookings_offset_twice"),),
+            time_dimension_specs=(DataSet.metric_time_dimension_spec(TimeGranularity.DAY),),
+        )
+    )
+
+    assert_plan_snapshot_text_equal(
+        request=request,
+        mf_test_session_state=mf_test_session_state,
+        plan=dataflow_plan,
+        plan_snapshot_text=dataflow_plan_as_text(dataflow_plan),
+    )
+
+    display_graph_if_requested(
+        request=request,
+        mf_test_session_state=mf_test_session_state,
+        dag_graph=dataflow_plan,
+    )

metricflow/test/fixtures/semantic_manifest_yamls/simple_manifest/metrics.yaml

@@ -578,3 +578,35 @@ metric:
       - name: bookings
         offset_window: 14 days
         alias: bookings_2_weeks_ago
+---
+metric:
+  name: "bookings_offset_once"
+  description: bookings metric offset once.
+  type: derived
+  type_params:
+    expr: 2 * bookings
+    metrics:
+      - name: bookings
+        offset_window: 5 days
+---
+metric:
+  name: "bookings_offset_twice"
+  description: bookings metric offset twice.
+  type: derived
+  type_params:
+    expr: 2 * bookings_offset_once
+    metrics:
+      - name: bookings_offset_once
+        offset_window: 5 days
+---
+metric:
+  name: booking_fees_since_start_of_month
+  description: nested derived metric with offset and multiple input metrics
+  type: derived
+  type_params:
+    expr: booking_fees - booking_fees_start_of_month
+    metrics:
+      - name: booking_fees
+        offset_to_grain: month
+        alias: booking_fees_start_of_month
+      - name: booking_fees

metricflow/test/integration/test_cases/itest_metrics.yaml

@@ -1468,3 +1468,93 @@ integration_test:
     GROUP BY
       COALESCE(subq_9.metric_time__day, subq_19.metric_time__day)
       , COALESCE(subq_9.listing__is_lux_latest, subq_19.listing__is_lux_latest)
+---
+integration_test:
+  name: nested_derived_metric_outer_offset
+  description: Tests a nested derived metric where the outer metric has an input metric with offset_window.
+  model: SIMPLE_MODEL
+  metrics: ["bookings_offset_twice"]
+  group_by_objs: [{"name": "metric_time"}]
+  check_query: |
+    SELECT
+      subq_9.ds AS metric_time__day
+      , 2 * bookings_offset_once AS bookings_offset_twice
+    FROM {{ source_schema }}.mf_time_spine subq_9
+    INNER JOIN (
+      SELECT
+        metric_time__day
+        , 2 * bookings AS bookings_offset_once
+      FROM (
+        SELECT
+          subq_3.ds AS metric_time__day
+          , SUM(subq_1.bookings) AS bookings
+        FROM {{ source_schema }}.mf_time_spine subq_3
+        INNER JOIN (
+          SELECT
+            {{ render_date_trunc("ds", TimeGranularity.DAY) }} AS metric_time__day
+            , 1 AS bookings
+          FROM {{ source_schema }}.fct_bookings bookings_source_src_1
+        ) subq_1
+        ON
+          {{ render_date_sub("subq_3", "ds", 5, TimeGranularity.DAY) }} = subq_1.metric_time__day
+        GROUP BY
+          subq_3.ds
+      ) subq_7
+    ) subq_8
+    ON
+      {{ render_date_sub("subq_9", "ds", 5, TimeGranularity.DAY) }} = subq_8.metric_time__day
+---
+integration_test:
+  name: nested_derived_metric_outer_offset_multiple_input_metrics
+  description: Tests a nested derived metric where the outer metric has one input metric with offset_to_grain and another with no offset.
+  model: SIMPLE_MODEL
+  metrics: ["booking_fees_since_start_of_month"]
+  group_by_objs: [{"name": "metric_time"}]
+  check_query: |
+    SELECT
+      metric_time__day
+      , booking_fees - booking_fees_start_of_month AS booking_fees_since_start_of_month
+    FROM (
+      SELECT
+        COALESCE(subq_8.metric_time__day, subq_14.metric_time__day) AS metric_time__day
+        , MAX(subq_8.booking_fees_start_of_month) AS booking_fees_start_of_month
+        , MAX(subq_14.booking_fees) AS booking_fees
+      FROM (
+        SELECT
+          subq_7.ds AS metric_time__day
+          , subq_5.booking_fees_start_of_month AS booking_fees_start_of_month
+        FROM {{ source_schema }}.mf_time_spine subq_7
+        INNER JOIN (
+          SELECT
+            metric_time__day
+            , booking_value * 0.05 AS booking_fees_start_of_month
+          FROM (
+            SELECT
+              {{ render_date_trunc("ds", TimeGranularity.DAY) }} AS metric_time__day
+              , SUM(booking_value) AS booking_value
+            FROM {{ source_schema }}.fct_bookings bookings_source_src_1
+            GROUP BY
+              {{ render_date_trunc("ds", TimeGranularity.DAY) }}
+          ) subq_4
+        ) subq_5
+        ON
+          {{ render_date_trunc("subq_7.ds", TimeGranularity.MONTH) }} = subq_5.metric_time__day
+      ) subq_8
+      FULL OUTER JOIN (
+        SELECT
+          metric_time__day
+          , booking_value * 0.05 AS booking_fees
+        FROM (
+          SELECT
+            {{ render_date_trunc("ds", TimeGranularity.DAY) }} AS metric_time__day
+            , SUM(booking_value) AS booking_value
+          FROM {{ source_schema }}.fct_bookings bookings_source_src_1
+          GROUP BY
+            {{ render_date_trunc("ds", TimeGranularity.DAY) }}
+        ) subq_13
+      ) subq_14
+      ON
+        subq_8.metric_time__day = subq_14.metric_time__day
+      GROUP BY
+        COALESCE(subq_8.metric_time__day, subq_14.metric_time__day)
+    ) subq_15

metricflow/test/query_rendering/test_derived_metric_rendering.py

@@ -323,3 +323,53 @@ def test_derived_offset_cumulative_metric(  # noqa: D
         sql_client=sql_client,
         node=dataflow_plan.sink_output_nodes[0].parent_node,
     )
+
+
+@pytest.mark.sql_engine_snapshot
+def test_nested_offsets(  # noqa: D
+    request: FixtureRequest,
+    mf_test_session_state: MetricFlowTestSessionState,
+    dataflow_plan_builder: DataflowPlanBuilder,
+    dataflow_to_sql_converter: DataflowToSqlQueryPlanConverter,
+    sql_client: SqlClient,
+    create_source_tables: bool,
+) -> None:
+    dataflow_plan = dataflow_plan_builder.build_plan(
+        query_spec=MetricFlowQuerySpec(
+            metric_specs=(MetricSpec(element_name="bookings_offset_twice"),),
+            time_dimension_specs=(MTD_SPEC_DAY,),
+        )
+    )
+
+    convert_and_check(
+        request=request,
+        mf_test_session_state=mf_test_session_state,
+        dataflow_to_sql_converter=dataflow_to_sql_converter,
+        sql_client=sql_client,
+        node=dataflow_plan.sink_output_nodes[0].parent_node,
+    )
+
+
+@pytest.mark.sql_engine_snapshot
+def test_nested_derived_metric_with_offset_multiple_input_metrics(  # noqa: D
+    request: FixtureRequest,
+    mf_test_session_state: MetricFlowTestSessionState,
+    dataflow_plan_builder: DataflowPlanBuilder,
+    dataflow_to_sql_converter: DataflowToSqlQueryPlanConverter,
+    sql_client: SqlClient,
+    create_source_tables: bool,
+) -> None:
+    dataflow_plan = dataflow_plan_builder.build_plan(
+        query_spec=MetricFlowQuerySpec(
+            metric_specs=(MetricSpec(element_name="booking_fees_since_start_of_month"),),
+            time_dimension_specs=(MTD_SPEC_DAY,),
+        )
+    )
+
+    convert_and_check(
+        request=request,
+        mf_test_session_state=mf_test_session_state,
+        dataflow_to_sql_converter=dataflow_to_sql_converter,
+        sql_client=sql_client,
+        node=dataflow_plan.sink_output_nodes[0].parent_node,
+    )