Add detail to error messages for debugging

metricflow/dataflow/builder/dataflow_plan_builder.py

@@ -221,12 +221,12 @@ def _build_plan(
     def _optimize_plan(self, plan: DataflowPlan, optimizations: FrozenSet[DataflowPlanOptimization]) -> DataflowPlan:
         optimizer_factory = DataflowPlanOptimizerFactory(self._node_data_set_resolver)
         for optimizer in optimizer_factory.get_optimizers(optimizations):
-            logger.debug(LazyFormat(lambda: f"Applying {optimizer.__class__.__name__}"))
+            logger.debug(LazyFormat(lambda: f"Applying optimizer: {optimizer.__class__.__name__}"))
             try:
                 plan = optimizer.optimize(plan)
                 logger.debug(
                     LazyFormat(
-                        lambda: f"After applying {optimizer.__class__.__name__}, the dataflow plan is:\n"
+                        lambda: f"After applying optimizer {optimizer.__class__.__name__}, the dataflow plan is:\n"
                         f"{indent(plan.structure_text())}"
                     )
                 )

metricflow/sql/optimizer/column_pruner.py

@@ -133,7 +133,13 @@ def visit_select_statement_node(self, node: SqlSelectStatementNode) -> SqlQueryP
         # SqlExpressionNode.
 
         if len(pruned_select_columns) == 0:
-            raise RuntimeError("All columns have been pruned - this indicates an bug in the pruner or in the inputs.")
+            raise RuntimeError(
+                "All columns have been removed - this indicates an bug in the pruner or in the inputs.\n"
+                f"Original column aliases: {[col.column_alias for col in node.select_columns]}\n"
+                f"Required column aliases: {self._required_column_aliases}\n"
+                f"Group bys: {node.group_bys}\n"
+                f"Distinct: {node.distinct}"
+            )
 
         # Based on the expressions in this select statement, figure out what column aliases are needed in the sources of
         # this query (i.e. tables or sub-queries in the FROM or JOIN clauses).