refactor: define planning_complexity tree property

Author: TrevorBergeron

bigframes/core/expression.py

@@ -108,6 +108,10 @@ def bind_all_variables(self, bindings: Mapping[str, Expression]) -> Expression:
     def is_bijective(self) -> bool:
         return False
 
+    @property
+    def is_raw_variable(self) -> bool:
+        return False
+
 
 @dataclasses.dataclass(frozen=True)
 class ScalarConstantExpression(Expression):
@@ -173,6 +177,10 @@ def bind_all_variables(self, bindings: Mapping[str, Expression]) -> Expression:
     def is_bijective(self) -> bool:
         return True
 
+    @property
+    def is_raw_variable(self) -> bool:
+        return True
+
 
 @dataclasses.dataclass(frozen=True)
 class OpExpression(Expression):

bigframes/core/nodes.py

@@ -38,6 +38,9 @@
     import bigframes.core.ordering as orderings
     import bigframes.session
 
+# A fixed number of variable to assume for overhead on some operations
+OVERHEAD_VARIABLES = 5
+
 
 @dataclass(frozen=True)
 class BigFrameNode:
@@ -107,6 +110,38 @@ def roots(self) -> typing.Set[BigFrameNode]:
     def schema(self) -> schemata.ArraySchema:
         ...
 
+    @property
+    @abc.abstractmethod
+    def variables_introduced(self) -> int:
+        """
+        Defines the number of variables generated by the current node. Used to estimate query planning complexity.
+        """
+        ...
+
+    @property
+    def relation_ops_created(self) -> int:
+        """
+        Defines the number of relational ops generated by the current node. Used to estimate query planning complexity.
+        """
+        return 1
+
+    @functools.cached_property
+    def total_variables(self) -> int:
+        return self.variables_introduced + sum(
+            map(lambda x: x.variables_introduced, self.child_nodes)
+        )
+
+    @functools.cached_property
+    def total_relational_ops(self) -> int:
+        return self.relation_ops_created + sum(
+            map(lambda x: x.relation_ops_created, self.child_nodes)
+        )
+
+    @property
+    def planning_complexity(self) -> int:
+        """Heuristic measure of planning complexity. Used to determine when to decompose overly complex computations."""
+        return self.total_variables * self.total_relational_ops
+
 
 @dataclass(frozen=True)
 class UnaryNode(BigFrameNode):
@@ -165,6 +200,10 @@ def join_mapping_to_schema_item(mapping: JoinColumnMapping):
         )
         return schemata.ArraySchema(items)
 
+    @functools.cached_property
+    def variables_introduced(self) -> int:
+        return OVERHEAD_VARIABLES
+
 
 @dataclass(frozen=True)
 class ConcatNode(BigFrameNode):
@@ -193,6 +232,11 @@ def schema(self) -> schemata.ArraySchema:
         )
         return schemata.ArraySchema(items)
 
+    @functools.cached_property
+    def variables_introduced(self) -> int:
+        """Defines the number of variables generated by the current node. Used to estimate query planning complexity."""
+        return OVERHEAD_VARIABLES
+
 
 # Input Nodex
 @dataclass(frozen=True)
@@ -216,6 +260,11 @@ def roots(self) -> typing.Set[BigFrameNode]:
     def schema(self) -> schemata.ArraySchema:
         return self.data_schema
 
+    @functools.cached_property
+    def variables_introduced(self) -> int:
+        """Defines the number of variables generated by the current node. Used to estimate query planning complexity."""
+        return len(self.schema.items) + 1
+
 
 # TODO: Refactor to take raw gbq object reference
 @dataclass(frozen=True)
@@ -252,6 +301,10 @@ def schema(self) -> schemata.ArraySchema:
         )
         return schemata.ArraySchema(items)
 
+    @functools.cached_property
+    def variables_introduced(self) -> int:
+        return len(self.columns) + len(self.hidden_ordering_columns)
+
 
 # Unary nodes
 @dataclass(frozen=True)
@@ -275,6 +328,10 @@ def schema(self) -> schemata.ArraySchema:
             schemata.SchemaItem(self.col_id, bigframes.dtypes.INT_DTYPE)
         )
 
+    @functools.cached_property
+    def variables_introduced(self) -> int:
+        return 1
+
 
 @dataclass(frozen=True)
 class FilterNode(UnaryNode):
@@ -287,6 +344,10 @@ def row_preserving(self) -> bool:
     def __hash__(self):
         return self._node_hash
 
+    @property
+    def variables_introduced(self) -> int:
+        return 1
+
 
 @dataclass(frozen=True)
 class OrderByNode(UnaryNode):
@@ -304,6 +365,15 @@ def __post_init__(self):
     def __hash__(self):
         return self._node_hash
 
+    @property
+    def variables_introduced(self) -> int:
+        return 0
+
+    @property
+    def relation_ops_created(self) -> int:
+        # Doesnt directly create any relational operations
+        return 0
+
 
 @dataclass(frozen=True)
 class ReversedNode(UnaryNode):
@@ -313,6 +383,15 @@ class ReversedNode(UnaryNode):
     def __hash__(self):
         return self._node_hash
 
+    @property
+    def variables_introduced(self) -> int:
+        return 0
+
+    @property
+    def relation_ops_created(self) -> int:
+        # Doesnt directly create any relational operations
+        return 0
+
 
 @dataclass(frozen=True)
 class ProjectionNode(UnaryNode):
@@ -332,6 +411,12 @@ def schema(self) -> schemata.ArraySchema:
         )
         return schemata.ArraySchema(items)
 
+    @property
+    def variables_introduced(self) -> int:
+        # ignore passthrough expressions
+        new_vars = sum(1 for i in self.assignments if not i[0].is_raw_variable)
+        return new_vars
+
 
 # TODO: Merge RowCount into Aggregate Node?
 # Row count can be compute from table metadata sometimes, so it is a bit special.
@@ -351,6 +436,11 @@ def schema(self) -> schemata.ArraySchema:
             (schemata.SchemaItem("count", bigframes.dtypes.INT_DTYPE),)
         )
 
+    @property
+    def variables_introduced(self) -> int:
+        # ignore passthrough expressions
+        return 1
+
 
 @dataclass(frozen=True)
 class AggregateNode(UnaryNode):
@@ -388,6 +478,10 @@ def schema(self) -> schemata.ArraySchema:
         )
         return schemata.ArraySchema(tuple([*by_items, *agg_items]))
 
+    @property
+    def variables_introduced(self) -> int:
+        return len(self.aggregations) + len(self.by_column_ids)
+
 
 @dataclass(frozen=True)
 class WindowOpNode(UnaryNode):
@@ -421,12 +515,25 @@ def schema(self) -> schemata.ArraySchema:
             schemata.SchemaItem(self.output_name, new_item_dtype)
         )
 
+    @property
+    def variables_introduced(self) -> int:
+        return 1
+
 
 @dataclass(frozen=True)
 class ReprojectOpNode(UnaryNode):
     def __hash__(self):
         return self._node_hash
 
+    @property
+    def variables_introduced(self) -> int:
+        return 0
+
+    @property
+    def relation_ops_created(self) -> int:
+        # This op is not a real transformation, just a hint to the sql generator
+        return 0
+
 
 @dataclass(frozen=True)
 class UnpivotNode(UnaryNode):
@@ -498,6 +605,19 @@ def infer_dtype(
         ]
         return schemata.ArraySchema((*index_items, *value_items, *passthrough_items))
 
+    @property
+    def variables_introduced(self) -> int:
+        return (
+            len(self.schema.items) - len(self.passthrough_columns) + OVERHEAD_VARIABLES
+        )
+
+    @property
+    def relation_ops_created(self) -> int:
+        """
+        Unpivot is essentially a cross join and a projection.
+        """
+        return 2
+
 
 @dataclass(frozen=True)
 class RandomSampleNode(UnaryNode):
@@ -513,3 +633,7 @@ def row_preserving(self) -> bool:
 
     def __hash__(self):
         return self._node_hash
+
+    @property
+    def variables_introduced(self) -> int:
+        return 1