Remove unused Config class that could not be connected to a SessionContext

Closes #322.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: timsaucer

crates/core/src/config.rs

@@ -30,8 +30,6 @@ use pyo3::prelude::*;
 pub mod catalog;
 pub mod common;
 
-#[allow(clippy::borrow_deref_ref)]
-mod config;
 #[allow(clippy::borrow_deref_ref)]
 pub mod context;
 #[allow(clippy::borrow_deref_ref)]
@@ -90,7 +88,6 @@ fn _internal(py: Python, m: Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<udaf::PyAggregateUDF>()?;
     m.add_class::<udwf::PyWindowUDF>()?;
     m.add_class::<udtf::PyTableFunction>()?;
-    m.add_class::<config::PyConfig>()?;
     m.add_class::<sql::logical::PyLogicalPlan>()?;
     m.add_class::<physical_plan::PyExecutionPlan>()?;
     m.add_class::<record_batch::PyRecordBatch>()?;

crates/core/src/lib.rs

@@ -149,20 +149,7 @@ interior-mutable state. In practice this means that any ``#[pyclass]`` containin
 ``Arc<RwLock<_>>`` or similar synchronized primitive must opt into ``#[pyclass(frozen)]``
 unless there is a compelling reason not to.
 
-The :mod:`datafusion` configuration helpers illustrate the preferred pattern. The
-``PyConfig`` class in :file:`src/config.rs` stores an ``Arc<RwLock<ConfigOptions>>`` and is
-explicitly frozen so callers interact with configuration state through provided methods
-instead of mutating the container directly:
-
-.. code-block:: rust
-
-    #[pyclass(from_py_object, name = "Config", module = "datafusion", subclass, frozen)]
-    #[derive(Clone)]
-    pub(crate) struct PyConfig {
-        config: Arc<RwLock<ConfigOptions>>,
-    }
-
-The same approach applies to execution contexts. ``PySessionContext`` in
+The execution context illustrates the preferred pattern. ``PySessionContext`` in
 :file:`src/context.rs` stays frozen even though it shares mutable state internally via
 ``SessionContext``. This ensures PyO3 tracks borrows correctly while Python-facing APIs
 clone the inner ``SessionContext`` or return new wrappers instead of mutating the

docs/source/contributor-guide/ffi.rst

@@ -18,6 +18,33 @@
 Upgrade Guides
 ==============
 
+DataFusion 54.0.0
+-----------------
+
+The ``Config`` class has been removed. It was a standalone wrapper around
+``ConfigOptions`` that could not be connected to a ``SessionContext``, making it
+effectively unusable. Use :py:class:`~datafusion.context.SessionConfig` instead,
+which is passed directly to ``SessionContext``.
+
+Before:
+
+.. code-block:: python
+
+    from datafusion import Config
+
+    config = Config()
+    config.set("datafusion.execution.batch_size", "4096")
+    # config could not be passed to SessionContext
+
+After:
+
+.. code-block:: python
+
+    from datafusion import SessionConfig, SessionContext
+
+    config = SessionConfig().set("datafusion.execution.batch_size", "4096")
+    ctx = SessionContext(config)
+
 DataFusion 53.0.0
 -----------------
 

docs/source/user-guide/upgrade-guides.rst

@@ -34,7 +34,6 @@
 from . import functions, object_store, substrait, unparser
 
 # The following imports are okay to remain as opaque to the user.
-from ._internal import Config
 from .catalog import Catalog, Table
 from .col import col, column
 from .common import DFSchema
@@ -76,7 +75,6 @@
     "Accumulator",
     "AggregateUDF",
     "Catalog",
-    "Config",
     "CsvReadOptions",
     "DFSchema",
     "DataFrame",

python/datafusion/__init__.py

@@ -20,7 +20,7 @@
 from concurrent.futures import ThreadPoolExecutor
 
 import pyarrow as pa
-from datafusion import Config, SessionContext, col, lit
+from datafusion import SessionContext, col, lit
 from datafusion import functions as f
 from datafusion.common import SqlSchema
 
@@ -34,16 +34,14 @@ def _run_in_threads(fn, count: int = 8) -> None:
 
 
 def test_concurrent_access_to_shared_structures() -> None:
-    """Exercise SqlSchema, Config, and DataFrame concurrently."""
+    """Exercise SqlSchema and DataFrame concurrently."""
 
     schema = SqlSchema("concurrency")
-    config = Config()
     ctx = SessionContext()
 
     batch = pa.record_batch([pa.array([1, 2, 3], type=pa.int32())], names=["value"])
     df = ctx.create_dataframe([[batch]])
 
-    config_key = "datafusion.execution.batch_size"
     expected_rows = batch.num_rows
 
     def worker(index: int) -> None:
@@ -54,41 +52,12 @@ def worker(index: int) -> None:
         assert isinstance(schema.views, list)
         assert isinstance(schema.functions, list)
 
-        config.set(config_key, str(1024 + index))
-        assert config.get(config_key) is not None
-        # Access the full config map to stress lock usage.
-        assert config_key in config.get_all()
-
         batches = df.collect()
         assert sum(batch.num_rows for batch in batches) == expected_rows
 
     _run_in_threads(worker, count=12)
 
 
-def test_config_set_during_get_all() -> None:
-    """Ensure config writes proceed while another thread reads all entries."""
-
-    config = Config()
-    key = "datafusion.execution.batch_size"
-
-    def reader() -> None:
-        for _ in range(200):
-            # get_all should not hold the lock while converting to Python objects
-            config.get_all()
-
-    def writer() -> None:
-        for index in range(200):
-            config.set(key, str(1024 + index))
-
-    with ThreadPoolExecutor(max_workers=2) as executor:
-        reader_future = executor.submit(reader)
-        writer_future = executor.submit(writer)
-        reader_future.result(timeout=10)
-        writer_future.result(timeout=10)
-
-    assert config.get(key) is not None
-
-
 def test_case_builder_reuse_from_multiple_threads() -> None:
     """Ensure the case builder can be safely reused across threads."""