Re: [I] `parquet_path_to_id_mapping` generates incorrect path for List types [iceberg-python]

["syun64 (via GitHub)" <gi...@apache.org>]

syun64 commented on issue #716:
URL: https://github.com/apache/iceberg-python/issues/716#issuecomment-2170966077

   Hi @cgbur and @felixscherz thank you for raising this and taking this investigation further. I'm not a polars user myself, but the difference in the behavior is quite interesting, and I think there would be value in trying to fix this issue.
   
   I just read the `write_table` API documentation in `pyarrow.parquet` and found something rather interesting:
   
   https://arrow.apache.org/docs/python/generated/pyarrow.parquet.write_table.html#pyarrow.parquet.write_table
   
   If you check the documentation for `use_compliant_nested_type` flag, it mentions that having `element` as the single item field name is the parquet compliant format as specified here on the [Parquet Spec for Nested Types](https://github.com/apache/parquet-format/blob/master/LogicalTypes.md#nested-types). PyArrow defaults to using this flag and writes the list element field name as `element`.
   
   For some reason it looks like polars has decided to use `item` - the non-parquet compliant list element name instead. While I'm curious about why the polars community has decided to go this route, I also think supporting both `element` or `item` name in the visitor may not be the worst thing, just to increase our scope of support.


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