rdblue commented on code in PR #6775:
URL: https://github.com/apache/iceberg/pull/6775#discussion_r1182742980
##########
python/pyiceberg/io/pyarrow.py:
##########
@@ -498,6 +503,96 @@ def expression_to_pyarrow(expr: BooleanExpression) ->
pc.Expression:
return boolean_expression_visit(expr, _ConvertToArrowExpression())
+@lru_cache
+def _get_file_format(file_format: FileFormat, **kwargs: Dict[str, Any]) ->
ds.FileFormat:
+ if file_format == FileFormat.PARQUET:
+ return ds.ParquetFileFormat(**kwargs)
+ else:
+ raise ValueError(f"Unsupported file format: {file_format}")
+
+
+def _construct_fragment(fs: FileSystem, data_file: DataFile,
file_format_kwargs: Dict[str, Any] = EMPTY_DICT) -> ds.Fragment:
+ _, path = PyArrowFileIO.parse_location(data_file.file_path)
+ return _get_file_format(data_file.file_format,
**file_format_kwargs).make_fragment(path, fs)
+
+
+def _read_deletes(fs: FileSystem, data_file: DataFile) -> Dict[str,
pa.ChunkedArray]:
+ delete_fragment = _construct_fragment(
+ fs, data_file, file_format_kwargs={"dictionary_columns":
("file_path",), "pre_buffer": True, "buffer_size": ONE_MEGABYTE}
+ )
+ table = ds.Scanner.from_fragment(fragment=delete_fragment).to_table()
+ table.unify_dictionaries()
+ return {
+ file.as_py(): table.filter(pc.field("file_path") == file).column("pos")
+ for file in table.column("file_path").chunks[0].dictionary
+ }
+
+
+class _OrderedChunkedArrayConsumer:
+ """
+ A wrapper to consume multiple individually ordered chunked-arrays
+ simultaneously as an ordered iterator
+ """
+
+ arrays: Tuple[pa.ChunkedArray, ...]
+ arrays_len: Tuple[int, ...]
+ arrays_pos: List[int]
+
+ def _reset(self) -> None:
+ self.arrays_pos = [0] * len(self.arrays)
+ self.arrays_len = tuple(len(array) for array in self.arrays)
+
+ def __init__(self, *arrays: pa.ChunkedArray) -> None:
+ self.arrays = arrays
+ self._reset()
+
+ def __iter__(self) -> _OrderedChunkedArrayConsumer:
Review Comment:
Isn't it a better pattern to always return a temporary iterator object that
references the arrays here rather than to keep global state that is reset when
this is reused?
Sharing state in the consumer object means this isn't thread safe, but the
Python pattern could easily be thread safe by separating the current position
state into its own object.
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