Add pycapsule interface to provide table provider to DataFusion

Signed-off-by: Tim Saucer <timsaucer@gmail.com>

python/Cargo.toml

@@ -20,6 +20,9 @@ delta_kernel.workspace = true
 # arrow
 arrow-schema = { workspace = true, features = ["serde"] }
 
+# datafusion
+datafusion-ffi = { workspace = true }
+
 # serde
 serde = { workspace = true }
 serde_json = { workspace = true }

python/deltalake/table.py

@@ -1423,6 +1423,42 @@ def repair(
     def transaction_versions(self) -> Dict[str, Transaction]:
         return self._table.transaction_versions()
 
+    def __datafusion_table_provider__(self) -> Any:
+        """Return the DataFusion table provider PyCapsule interface.
+
+        To support DataFusion features such as push down filtering, this function will return a PyCapsule
+        interface that conforms to the FFI Table Provider required by DataFusion. From an end user perspective
+        you should not need to call this function directly. Instead you can use ``register_table_provider`` in
+        the DataFusion SessionContext.
+
+        Returns:
+            A PyCapsule DataFusion TableProvider interface.
+
+        Example:
+            ```python
+            from deltalake import DeltaTable, write_deltalake
+            from datafusion import SessionContext
+            import pyarrow as pa
+            data = pa.table({"x": [1, 2, 3], "y": [4, 5, 6]})
+            write_deltalake("tmp", data)
+            dt = DeltaTable("tmp")
+            ctx = SessionContext()
+            ctx.register_table_provider("test", table)
+            ctx.table("test").show()
+            ```
+            Results in
+            ```
+            DataFrame()
+            +----+----+----+
+            | c3 | c1 | c2 |
+            +----+----+----+
+            | 4  | 6  | a  |
+            | 6  | 5  | b  |
+            | 5  | 4  | c  |
+            +----+----+----+
+            ```
+        """
+        return self._table.__datafusion_table_provider__()
 
 class TableMerger:
     """API for various table `MERGE` commands."""

python/src/lib.rs

@@ -6,13 +6,16 @@ mod schema;
 mod utils;
 
 use std::collections::{HashMap, HashSet};
+use std::ffi::CString;
 use std::future::IntoFuture;
 use std::str::FromStr;
+use std::sync::Arc;
 use std::time;
 use std::time::{SystemTime, UNIX_EPOCH};
 
 use arrow::pyarrow::PyArrowType;
 use chrono::{DateTime, Duration, FixedOffset, Utc};
+use datafusion_ffi::table_provider::FFI_TableProvider;
 use delta_kernel::expressions::Scalar;
 use delta_kernel::schema::StructField;
 use deltalake::arrow::compute::concat_batches;
@@ -58,7 +61,7 @@ use futures::future::join_all;
 use pyo3::exceptions::{PyRuntimeError, PyValueError};
 use pyo3::prelude::*;
 use pyo3::pybacked::PyBackedStr;
-use pyo3::types::{PyDict, PyFrozenSet};
+use pyo3::types::{PyCapsule, PyDict, PyFrozenSet};
 use serde_json::{Map, Value};
 
 use crate::error::DeltaProtocolError;
@@ -1240,6 +1243,17 @@ impl RawDeltaTable {
             .map(|(app_id, transaction)| (app_id, PyTransaction::from(transaction)))
             .collect()
     }
+
+    fn __datafusion_table_provider__<'py>(
+        &self,
+        py: Python<'py>,
+    ) -> PyResult<Bound<'py, PyCapsule>> {
+        let name = CString::new("datafusion_table_provider").unwrap();
+
+        let provider = FFI_TableProvider::new(Arc::new(self._table.clone()), false);
+
+        PyCapsule::new_bound(py, provider, Some(name.clone()))
+    }
 }
 
 fn set_post_commithook_properties(