GH-49927: [Python][Parquet] Expose bloom_filter_offset and bloom_filter_length to Python in column chunk metadata

[haziqishere]

Rationale for this change

ColumnChunkMetaData.to_dict() method omits bloom_filter_offset and bloom_filter_length even when a bloom filter is written to the Parquet file. Users cannot programmatically verify bloom filter presence via the Python metadata API without resorting to file size comparison.

What changes are included in this PR?

1. python/pyarrow/includes/libparquet.pxd: Declare bloom_filter_offset() and bloom_filter_length() (both optional[int64_t]) on CColumnChunkMetaData. This is to expose the existing C++ methods to Cython.
2. python/pyarrow/_parquet.pyx: Add bloom_filter_offset and bloom_filter_length properties to ColumnChunkMetaData (returns int when set, None otherwise). Add both fields to to_dict() and __repr__.
3. python/pyarrow/tests/parquet/test_metadata.py: Add test_bloom_filter_offset_in_metadata verifying that columns with a bloom filter expose non-None integer values and that to_dict() contains the keys, while columns without a bloom filter return None.

Are these changes tested?

Yes. test_bloom_filter_offset_in_metadata in test_metadata.py covers:

• Column with bloom filter: bloom_filter_offset and bloom_filter_length are non-None integers
• Column without bloom filter: both return None
• Both keys present in to_dict() output

Here is closer look on the logic output:

output:

col_a bloom_filter_offset: 10699
col_a bloom_filter_length: 1040
col_b bloom_filter_offset: None
col_b bloom_filter_length: None

col_a to_dict(): {'file_offset': 0, 'file_path': '', 'physical_type': 'BYTE_ARRAY', 'num_values': 1000, 'path_in_schema': 'a', 'is_stats_set': True, 'statistics': {'has_min_max': True, 'min': 'id_0', 'max': 'id_999', 'null_count': 0, 'distinct_count': None, 'num_values': 1000, 'physical_type': 'BYTE_ARRAY'}, 'geo_statistics': None, 'compression': 'SNAPPY', 'encodings': ('PLAIN', 'RLE', 'RLE_DICTIONARY'), 'has_dictionary_page': True, 'dictionary_page_offset': 4, 'data_page_offset': 4035, 'total_compressed_size': 5336, 'total_uncompressed_size': 11208, 'bloom_filter_offset': 10699, 'bloom_filter_length': 1040}

• GitHub Issue: [Python][Parquet] Expose bloom_filter_offset and bloom_filter_length to Python in column chunk metadata #49927

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

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Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

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See also:

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• Contribution Guidelines - Contributing Overview

[github-actions]

⚠️ GitHub issue #49927 has been automatically assigned in GitHub to PR creator.

[raulcd]

This seems reasonable to me. Could you update the the title to something like the following to make it clear that this is about exposing this to Python not about a fix on C++?
GH-49927: [Python][Parquet] Expose bloom_filter_offset and bloom_filter_length to Python in column chunk metadata

[haziqishere]

@raulcd thanks for reviewing and the feedback. I've updated the items respectively 😄

[raulcd]

Exposing this to PyArrow looks good to me.
@mapleFU @pitrou do you want to take a look?