[I] [Python][Parquet] read_schema drops extension types (UUID returned as fixed_size_binary[16]) [arrow]

["Kuinox (via GitHub)" <gi...@apache.org>]

Kuinox opened a new issue, #48254:
URL: https://github.com/apache/arrow/issues/48254

   ### Describe the bug, including details regarding any error messages, version, and platform.
   
    ### Summary
     UUID extension types are preserved in tables but dropped by `pyarrow.parquet.read_schema`, creating an asymmetry between the table’s schema and the schema read from Parquet metadata.
   
     ### Steps to Reproduce
     ```python
     import pyarrow as pa
     import pyarrow.parquet as pq
     from pathlib import Path
     import tempfile
   
     data = [
         b'\xe4`\xf9p\x83QGN\xac\x7f\xa4g>\x4b\xa8\xcb',
         b'\x1et\x14\x95\xee\xd5C\xea\x9b\xd7s\xdc\x91BK\xaf',
         None,
     ]
     table = pa.table([pa.array(data, type=pa.uuid())], names=["ext"])
     print("table schema type:", table.schema.field("ext").type)  # extension<arrow.uuid>
   
     path = Path(tempfile.gettempdir()) / "uuid_ext_test.parquet"
     pq.write_table(table, path, store_schema=False)
   
     print("read_schema type:", pq.read_schema(path).field("ext").type)
     print("read_table schema type:", pq.read_table(path).schema.field("ext").type)
   
     ### Expected Behavior
   
     read_schema(path) should yield the same type as the table schema (and read_table), i.e., extension<arrow.uuid>.
   
     ### Actual Behavior
   
     read_schema(path) returns fixed_size_binary[16], while the original table.schema and read_table(path).schema both report extension<arrow.uuid>, so metadata-based schema inspection drops the extension type.
   
     ### Notes
   
     - Observed with the current pyarrow wheel (22.0.0) and current main sources.
     - ParquetFile(...).schema_arrow preserves the extension type; read_schema does not
   
   ### Component(s)
   
   Python, Parquet


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Re: [I] [Python][Parquet] read_schema drops extension types (UUID returned as fixed_size_binary[16]) [arrow]

["raulcd (via GitHub)" <gi...@apache.org>]

raulcd closed issue #48254: [Python][Parquet] read_schema drops extension types (UUID returned as fixed_size_binary[16])
URL: https://github.com/apache/arrow/issues/48254


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Re: [I] [Python][Parquet] read_schema drops extension types (UUID returned as fixed_size_binary[16]) [arrow]

["rohanjain101 (via GitHub)" <gi...@apache.org>]

rohanjain101 commented on issue #48254:
URL: https://github.com/apache/arrow/issues/48254#issuecomment-3598662488

   Similar to https://github.com/apache/arrow/issues/48169


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Re: [I] [Python][Parquet] read_schema drops extension types (UUID returned as fixed_size_binary[16]) [arrow]

["raulcd (via GitHub)" <gi...@apache.org>]

raulcd commented on issue #48254:
URL: https://github.com/apache/arrow/issues/48254#issuecomment-4535125535

   Issue resolved by pull request 48255
   https://github.com/apache/arrow/pull/48255


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