Add profitability guards for join filter pushdown

ci/run_cudf_polars_polars_tests.sh

@@ -62,7 +62,7 @@ DESELECTED_TESTS_STR=$(printf -- " --deselect %s" "${DESELECTED_TESTS[@]}")
 # Don't quote the `DESELECTED_...` variable because `pytest` can't handle
 # multiple quoted arguments inline
 # shellcheck disable=SC2086
-# Fail fast (-x) because failed tests pollute the state
+# Fail fast (-x) rather than trying to continue because failed tests pollute the state
 echo "Run polars tests with injected in-memory GPU engine"
 python "${TIMEOUT_TOOL_PATH}" --enable-python 4800 \
    python -m pytest \
@@ -90,7 +90,6 @@ python "${TIMEOUT_TOOL_PATH}" --enable-python 4800 \
        --import-mode=importlib \
        --cache-clear \
        -x \
-       -v \
        -m "" \
        -p cudf_polars.testing.inject_gpu_engine \
        -W ignore::ResourceWarning \

ci/test_python_other.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-FileCopyrightText: Copyright (c) 2022-2026, NVIDIA CORPORATION.
+# SPDX-FileCopyrightText: Copyright (c) 2022-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
 set -euo pipefail
@@ -42,8 +42,9 @@ timeout 30m ./ci/run_custreamz_pytests.sh \
   --cov-report=term
 
 rapids-logger "pytest cudf-polars"
+# Fail fast (-x) rather than trying to continue because failed tests pollute the state
 ./ci/run_cudf_polars_pytests.sh \
-  -vv \
+  -x \
   --junitxml="${RAPIDS_TESTS_DIR}/junit-cudf-polars.xml" \
   --numprocesses=4 \
   --dist=worksteal \

ci/test_wheel_cudf_polars.sh

@@ -91,7 +91,6 @@ for version in "${VERSIONS[@]}"; do
 
     # Fail fast (-x) rather than trying to continue because failed tests pollute the state
     ./ci/run_cudf_polars_pytests.sh \
-        -vv \
         "${COVERAGE_ARGS[@]}" \
         --numprocesses=4 \
         --dist=worksteal \

python/cudf_polars/cudf_polars/dsl/traversal.py

@@ -1,11 +1,11 @@
-# SPDX-FileCopyrightText: Copyright (c) 2024-2025, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-FileCopyrightText: Copyright (c) 2024-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
 """Traversal and visitor utilities for nodes."""
 
 from __future__ import annotations
 
-from collections import deque
+from collections import Counter, deque
 from typing import TYPE_CHECKING, Generic
 
 from cudf_polars.typing import (
@@ -15,19 +15,40 @@
 )
 
 if TYPE_CHECKING:
-    from collections.abc import Callable, Generator, MutableMapping, Sequence
+    from collections.abc import Callable, Generator, Mapping, MutableMapping, Sequence
 
     from cudf_polars.typing import GenericTransformer, NodeT
 
 
 __all__: list[str] = [
     "CachingVisitor",
+    "collect_refcount",
     "make_recursive",
+    "post_traversal",
     "reuse_if_unchanged",
     "traversal",
 ]
 
 
+def collect_refcount(nodes: Sequence[NodeT]) -> Mapping[NodeT, int]:
+    """
+    Determine reference counts of all nodes in a DAG.
+
+    Parameters
+    ----------
+    nodes
+         Sequence of root nodes
+
+    Returns
+    -------
+    Mapping from nodes to frequency of occurrence in the DAG.
+    """
+    refcount = Counter(nodes)
+    for node in traversal(nodes):
+        refcount.update(node.children)
+    return refcount
+
+
 def traversal(nodes: Sequence[NodeT]) -> Generator[NodeT, None, None]:
     """
     Pre-order traversal of nodes in an expression.