Replace is_table with as_sql_table_node (#1502)

This removes `SqlQueryPlanNode.is_table` and replaces it with a typed
accessor for parallelism with `as_select_node`. This is helpful in
handling some use cases for CTEs.

metricflow/sql/render/sql_plan_renderer.py

@@ -190,7 +190,7 @@ def _render_from_section(self, from_source: SqlQueryPlanNode, from_source_alias:
         from_render_result = self._render_node(from_source)
 
         from_section_lines = []
-        if from_source.is_table:
+        if from_source.as_sql_table_node is not None:
             from_section_lines.append(f"FROM {from_render_result.sql} {from_source_alias}")
         else:
             from_section_lines.append("FROM (")
@@ -228,7 +228,7 @@ def _render_joins_section(self, join_descriptions: Sequence[SqlJoinDescription])
                 on_condition_rendered = self.EXPR_RENDERER.render_sql_expr(join_description.on_condition)
                 params = params.merge(on_condition_rendered.bind_parameter_set)
 
-            if join_description.right_source.is_table:
+            if join_description.right_source.as_sql_table_node is not None:
                 join_section_lines.append(join_description.join_type.value)
                 join_section_lines.append(
                     textwrap.indent(

metricflow/sql/sql_plan.py

@@ -41,14 +41,14 @@ def accept(self, visitor: SqlQueryPlanNodeVisitor[VisitorOutputT]) -> VisitorOut
 
     @property
     @abstractmethod
-    def is_table(self) -> bool:
-        """Returns whether this node resolves to a table (vs. a query)."""
+    def as_select_node(self) -> Optional[SqlSelectStatementNode]:
+        """If possible, return this as a select statement node."""
         raise NotImplementedError
 
     @property
     @abstractmethod
-    def as_select_node(self) -> Optional[SqlSelectStatementNode]:
-        """If possible, return this as a select statement node."""
+    def as_sql_table_node(self) -> Optional[SqlTableNode]:
+        """If possible, return this as SQL table node."""
         raise NotImplementedError
 
     @abstractmethod
@@ -208,14 +208,15 @@ def displayed_properties(self) -> Sequence[DisplayedProperty]:  # noqa: D102
     def accept(self, visitor: SqlQueryPlanNodeVisitor[VisitorOutputT]) -> VisitorOutputT:  # noqa: D102
         return visitor.visit_select_statement_node(self)
 
-    @property
-    def is_table(self) -> bool:  # noqa: D102
-        return False
-
     @property
     def as_select_node(self) -> Optional[SqlSelectStatementNode]:  # noqa: D102
         return self
 
+    @property
+    @override
+    def as_sql_table_node(self) -> Optional[SqlTableNode]:
+        return None
+
     @property
     @override
     def description(self) -> str:
@@ -271,10 +272,6 @@ def displayed_properties(self) -> Sequence[DisplayedProperty]:  # noqa: D102
     def accept(self, visitor: SqlQueryPlanNodeVisitor[VisitorOutputT]) -> VisitorOutputT:  # noqa: D102
         return visitor.visit_table_node(self)
 
-    @property
-    def is_table(self) -> bool:  # noqa: D102
-        return True
-
     @property
     def as_select_node(self) -> Optional[SqlSelectStatementNode]:  # noqa: D102
         return None
@@ -289,6 +286,11 @@ def nearest_select_columns(
                 return cte_node.nearest_select_columns(cte_source_mapping)
         return None
 
+    @property
+    @override
+    def as_sql_table_node(self) -> Optional[SqlTableNode]:
+        return self
+
 
 @dataclass(frozen=True, eq=False)
 class SqlSelectQueryFromClauseNode(SqlQueryPlanNode):
@@ -318,10 +320,6 @@ def description(self) -> str:  # noqa: D102
     def accept(self, visitor: SqlQueryPlanNodeVisitor[VisitorOutputT]) -> VisitorOutputT:  # noqa: D102
         return visitor.visit_query_from_clause_node(self)
 
-    @property
-    def is_table(self) -> bool:  # noqa: D102
-        return False
-
     @property
     def as_select_node(self) -> Optional[SqlSelectStatementNode]:  # noqa: D102
         return None
@@ -332,14 +330,18 @@ def nearest_select_columns(
     ) -> Optional[Sequence[SqlSelectColumn]]:
         return None
 
+    @property
+    @override
+    def as_sql_table_node(self) -> Optional[SqlTableNode]:
+        return None
+
 
 @dataclass(frozen=True, eq=False)
 class SqlCreateTableAsNode(SqlQueryPlanNode):
     """An SQL node representing a CREATE TABLE AS statement.
 
     Attributes:
         sql_table: The SQL table to create.
-        parent_node: The parent query plan node.
     """
 
     sql_table: SqlTable
@@ -361,12 +363,12 @@ def accept(self, visitor: SqlQueryPlanNodeVisitor[VisitorOutputT]) -> VisitorOut
 
     @property
     @override
-    def is_table(self) -> bool:
-        return False
+    def as_select_node(self) -> Optional[SqlSelectStatementNode]:
+        return None
 
     @property
     @override
-    def as_select_node(self) -> Optional[SqlSelectStatementNode]:
+    def as_sql_table_node(self) -> Optional[SqlTableNode]:
         return None
 
     @property
@@ -415,15 +417,15 @@ def render_node(self) -> SqlQueryPlanNode:  # noqa: D102
 class SqlCteNode(SqlQueryPlanNode):
     """Represents a single common table expression."""
 
-    select_statement: SqlSelectStatementNode
+    select_statement: SqlQueryPlanNode
     cte_alias: str
 
     def __post_init__(self) -> None:  # noqa: D105
         super().__post_init__()
         assert len(self.parent_nodes) == 1
 
     @staticmethod
-    def create(select_statement: SqlSelectStatementNode, cte_alias: str) -> SqlCteNode:  # noqa: D102
+    def create(select_statement: SqlQueryPlanNode, cte_alias: str) -> SqlCteNode:  # noqa: D102
         return SqlCteNode(
             parent_nodes=(select_statement,),
             select_statement=select_statement,
@@ -436,12 +438,12 @@ def accept(self, visitor: SqlQueryPlanNodeVisitor[VisitorOutputT]) -> VisitorOut
 
     @property
     @override
-    def is_table(self) -> bool:
-        return False
+    def as_select_node(self) -> Optional[SqlSelectStatementNode]:
+        return None
 
     @property
     @override
-    def as_select_node(self) -> Optional[SqlSelectStatementNode]:
+    def as_sql_table_node(self) -> Optional[SqlTableNode]:
         return None
 
     @property