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fix: Fix issues with chunked arrow data #1700

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May 8, 2025
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24 changes: 20 additions & 4 deletions bigframes/core/local_data.py
Original file line number Diff line number Diff line change
Expand Up @@ -86,7 +86,7 @@ def from_pyarrow(self, table: pa.Table) -> ManagedArrowTable:
columns: list[pa.ChunkedArray] = []
fields: list[schemata.SchemaItem] = []
for name, arr in zip(table.column_names, table.columns):
new_arr, bf_type = _adapt_arrow_array(arr)
new_arr, bf_type = _adapt_chunked_array(arr)
columns.append(new_arr)
fields.append(schemata.SchemaItem(name, bf_type))

Expand Down Expand Up @@ -279,10 +279,26 @@ def _adapt_pandas_series(
raise e


def _adapt_arrow_array(
array: Union[pa.ChunkedArray, pa.Array]
) -> tuple[Union[pa.ChunkedArray, pa.Array], bigframes.dtypes.Dtype]:
def _adapt_chunked_array(
chunked_array: pa.ChunkedArray,
) -> tuple[pa.ChunkedArray, bigframes.dtypes.Dtype]:
if len(chunked_array.chunks) == 0:
return _adapt_arrow_array(chunked_array.combine_chunks())
dtype = None
arrays = []
for chunk in chunked_array.chunks:
array, arr_dtype = _adapt_arrow_array(chunk)
arrays.append(array)
dtype = dtype or arr_dtype
assert dtype is not None
return pa.chunked_array(arrays), dtype


def _adapt_arrow_array(array: pa.Array) -> tuple[pa.Array, bigframes.dtypes.Dtype]:
"""Normalize the array to managed storage types. Preverse shapes, only transforms values."""
if array.offset != 0: # Offset arrays don't have all operations implemented
return _adapt_arrow_array(pa.concat_arrays([array]))

if pa.types.is_struct(array.type):
assert isinstance(array, pa.StructArray)
assert isinstance(array.type, pa.StructType)
Expand Down
20 changes: 20 additions & 0 deletions tests/unit/test_local_data.py
Original file line number Diff line number Diff line change
Expand Up @@ -44,3 +44,23 @@ def test_local_data_well_formed_round_trip():
local_entry = local_data.ManagedArrowTable.from_pandas(pd_data)
result = pd.DataFrame(local_entry.itertuples(), columns=pd_data.columns)
pandas.testing.assert_frame_equal(pd_data_normalized, result, check_dtype=False)


def test_local_data_well_formed_round_trip_chunked():
pa_table = pa.Table.from_pandas(pd_data, preserve_index=False)
as_rechunked_pyarrow = pa.Table.from_batches(pa_table.to_batches(max_chunksize=2))
local_entry = local_data.ManagedArrowTable.from_pyarrow(as_rechunked_pyarrow)
result = pd.DataFrame(local_entry.itertuples(), columns=pd_data.columns)
pandas.testing.assert_frame_equal(pd_data_normalized, result, check_dtype=False)


def test_local_data_well_formed_round_trip_sliced():
pa_table = pa.Table.from_pandas(pd_data, preserve_index=False)
as_rechunked_pyarrow = pa.Table.from_batches(pa_table.slice(2, 4).to_batches())
local_entry = local_data.ManagedArrowTable.from_pyarrow(as_rechunked_pyarrow)
result = pd.DataFrame(local_entry.itertuples(), columns=pd_data.columns)
pandas.testing.assert_frame_equal(
pd_data_normalized[2:4].reset_index(drop=True),
result.reset_index(drop=True),
check_dtype=False,
)