fix filter pushdown bug

Author: TrevorBergeron

bigframes/_config/experiment_options.py

@@ -27,8 +27,7 @@ class ExperimentOptions:
     def __init__(self):
         self._semantic_operators: bool = False
         self._ai_operators: bool = False
-        # TODO: DO NOT SUBMIT, revert before submitting
-        self._sql_compiler: Literal["legacy", "stable", "experimental"] = "experimental"
+        self._sql_compiler: Literal["legacy", "stable", "experimental"] = "stable"
 
     @property
     def semantic_operators(self) -> bool:

bigframes/core/compile/sqlglot/expressions/generic_ops.py

@@ -94,7 +94,7 @@ def _(*operands: TypedExpr, op: ops.SqlScalarOp) -> sge.Expression:
 
 @register_unary_op(ops.isnull_op)
 def _(expr: TypedExpr) -> sge.Expression:
-    return sge.Is(this=expr.expr, expression=sge.Null())
+    return sge.Is(this=sge.paren(expr.expr), expression=sge.Null())
 
 
 @register_unary_op(ops.MapOp, pass_op=True)
@@ -125,7 +125,7 @@ def _(expr: TypedExpr, op: ops.MapOp) -> sge.Expression:
 
 @register_unary_op(ops.notnull_op)
 def _(expr: TypedExpr) -> sge.Expression:
-    return sge.Not(this=sge.Is(this=expr.expr, expression=sge.Null()))
+    return sge.Not(this=sge.Is(this=sge.paren(expr.expr), expression=sge.Null()))
 
 
 @register_ternary_op(ops.where_op)

bigframes/core/rewrite/as_sql.py

@@ -105,6 +105,13 @@ def _add_cdefs(
 def _try_add_filter(
     select: sql_nodes.SqlSelectNode, predicates: Sequence[expression.Expression]
 ) -> Optional[sql_nodes.SqlSelectNode]:
+    # Filter implicitly happens first, so merging it into ths select will modify non-scalar col expressions
+    if not all(cdef.expression.is_scalar_expr for cdef in select.selections):
+        return None
+    if not all(
+        sort_expr.scalar_expression.is_scalar_expr for sort_expr in select.sorting
+    ):
+        return None
     # Constraint: filters can only be merged if they are scalar expression after binding
     new_predicates = []
     # bind variables, merge predicates

tests/unit/_config/test_experiment_options.py

@@ -51,7 +51,7 @@ def test_ai_operators_set_true_shows_warning():
 def test_sql_compiler_default_stable():
     options = experiment_options.ExperimentOptions()
 
-    assert options.sql_compiler == "experimental"
+    assert options.sql_compiler == "stable"
 
 
 def test_sql_compiler_set_experimental_shows_warning():