Michael Milton created ARROW-16431:
--------------------------------------
Summary: Improve error message in append_row_groups() when
appending disjoint metadata
Key: ARROW-16431
URL: https://issues.apache.org/jira/browse/ARROW-16431
Project: Apache Arrow
Issue Type: Improvement
Reporter: Michael Milton
Currently if you try to append together metadata from row groups with different
schemas (?), you get the following error:
{code:java}
File
"/home/mmilton/.conda/envs/mmilton/envs/driverpipe/lib/python3.9/site-packages/dask/dataframe/io/parquet/arrow.py",
line 52, in _append_row_groups
metadata.append_row_groups(md)
File "pyarrow/_parquet.pyx", line 628, in
pyarrow._parquet.FileMetaData.append_row_groups
self._metadata.AppendRowGroups(deref(c_metadata))
RuntimeError: AppendRowGroups requires equal schemas.
{code}
What would be useful here is to actually pass the schema difference in the
error object in terms of which columns disagree. This information should _also_
be in the error message.
For example if it said:
{code:java}
RuntimeError: AppendRowGroups requires equal schemas. Column "foo" was
previously an int32 but the latest row group is storing it as an int64
{code}
--
This message was sent by Atlassian Jira
(v8.20.7#820007)
