From 6e63ea8162d906412db388a91d3f4f13f8f9fbc5 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Thu, 16 Mar 2023 11:46:04 -0700
Subject: [PATCH 1/2] BUG: pickling ArrowExtensionArray with _pa_data rename

---
 pandas/core/arrays/arrow/array.py    |  8 ++++++--
 pandas/tests/extension/test_arrow.py | 16 ++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/arrow/array.py b/pandas/core/arrays/arrow/array.py
index c07aee737934b..2cfed49926f15 100644
--- a/pandas/core/arrays/arrow/array.py
+++ b/pandas/core/arrays/arrow/array.py
@@ -433,11 +433,15 @@ def __abs__(self) -> Self:
     # https://issues.apache.org/jira/browse/ARROW-10739 is addressed
     def __getstate__(self):
         state = self.__dict__.copy()
-        state["_data"] = self._pa_array.combine_chunks()
+        state["_pa_array"] = self._pa_array.combine_chunks()
         return state
 
     def __setstate__(self, state) -> None:
-        state["_pa_array"] = pa.chunked_array(state["_data"])
+        if "_data" in state:
+            data = state["_data"]
+        else:
+            data = state["_pa_array"]
+        state["_pa_array"] = pa.chunked_array(data)
         self.__dict__.update(state)
 
     def _cmp_method(self, other, op):
diff --git a/pandas/tests/extension/test_arrow.py b/pandas/tests/extension/test_arrow.py
index fcca2e4fa8e8e..cff9e99c9317e 100644
--- a/pandas/tests/extension/test_arrow.py
+++ b/pandas/tests/extension/test_arrow.py
@@ -2351,3 +2351,19 @@ def test_concat_empty_arrow_backed_series(dtype):
     expected = ser.copy()
     result = pd.concat([ser[np.array([], dtype=np.bool_)]])
     tm.assert_series_equal(result, expected)
+
+
+# _data was renamed to _pa_data
+class OldArrowExtensionArray(ArrowExtensionArray):
+    def __getstate__(self):
+        state = super().__getstate__()
+        state["_data"] = state.pop("_pa_array")
+        return state
+
+
+def test_pickle_old_arrowextensionarray():
+    data = pa.array([1])
+    expected = OldArrowExtensionArray(data)
+    result = pickle.loads(pickle.dumps(expected))
+    tm.assert_extension_array_equal(result, expected)
+    assert result._pa_array == pa.chunked_array(data)

From 42c7fabdc5809ac12aafc5b257c25f7adeadbf48 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Thu, 16 Mar 2023 11:58:43 -0700
Subject: [PATCH 2/2] pop _data if exists

---
 pandas/core/arrays/arrow/array.py    | 2 +-
 pandas/tests/extension/test_arrow.py | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/arrays/arrow/array.py b/pandas/core/arrays/arrow/array.py
index 2cfed49926f15..551b925f42579 100644
--- a/pandas/core/arrays/arrow/array.py
+++ b/pandas/core/arrays/arrow/array.py
@@ -438,7 +438,7 @@ def __getstate__(self):
 
     def __setstate__(self, state) -> None:
         if "_data" in state:
-            data = state["_data"]
+            data = state.pop("_data")
         else:
             data = state["_pa_array"]
         state["_pa_array"] = pa.chunked_array(data)
diff --git a/pandas/tests/extension/test_arrow.py b/pandas/tests/extension/test_arrow.py
index cff9e99c9317e..2378710555340 100644
--- a/pandas/tests/extension/test_arrow.py
+++ b/pandas/tests/extension/test_arrow.py
@@ -2367,3 +2367,4 @@ def test_pickle_old_arrowextensionarray():
     result = pickle.loads(pickle.dumps(expected))
     tm.assert_extension_array_equal(result, expected)
     assert result._pa_array == pa.chunked_array(data)
+    assert not hasattr(result, "_data")