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https://issues.apache.org/jira/browse/ARROW-4516?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rok Mihevc updated ARROW-4516:
------------------------------
External issue URL: https://github.com/apache/arrow/issues/21067
> [Python] Error while creating a ParquetDataset on a path without
> `_common_dataset` but with an empty `_tempfile`
> ----------------------------------------------------------------------------------------------------------------
>
> Key: ARROW-4516
> URL: https://issues.apache.org/jira/browse/ARROW-4516
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Affects Versions: 0.12.0
> Reporter: yogesh garg
> Priority: Major
> Labels: parquet
> Fix For: 0.14.0
>
>
> I suspect that there's an error in this line of code:
> https://github.com/apache/arrow/blob/master/python/pyarrow/parquet.py#L926
> While validating schema in the initialisation of a {{ParquetDataset}}, we
> assume that if {{_common_metadata}} file does not exist, the schema should be
> inferred from the first piece of that dataset. The first piece, in my
> experience, could refer to a file named with an underscore, that does not
> necessarily have to contain the schema, and could be an empty file, e.g.
> {{_tempfile}}.
> {code:bash}
> /tmp/pq/
> ├── part1.parquet
> └── _tempfile
> {code}
> This behavior is allowed by the parquet specification, and we should probably
> ignore such pieces.
> On a cursory look, we could do either of the following.
> 1. Choose the first piece with path that does not start with "_"
> 2. Sort pieces by name, but put all the "_" pieces later while making the
> manifest.
> https://github.com/apache/arrow/blob/master/python/pyarrow/parquet.py#L729
> 3. Silently exclude all the files starting with "_" here, but this will need
> to be tested:
> https://github.com/apache/arrow/blob/master/python/pyarrow/parquet.py#L770
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