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Joris Van den Bossche commented on ARROW-10695:
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bq. Is there a separate issue open for the partition_filename_cb to be added to
ds.write_dataset()? I have been using that feature to "repartition" Dataset A
with many small files into Dataset B with one file per partition (larger
physical file, less fragments).
[~ldacey] Could you open an issue for it, describing the use case for which you
needed {{partition_filename_cb}} ?
It's not added in the new dataset implementation (it's also a bit harder to
implement since it would need a Python callback from C++), so it would be good
to first see what are the use cases and if that needs such a callback or if it
can be solved differently.
bq. Unfortunately, there is no metadata_collector for ds.write_dataset() yet.
Same for this one, it would be interesting to describe your use case for it in
a new JIRA.
> [C++][Dataset] Allow to use a UUID in the basename_template when writing a
> dataset
> ----------------------------------------------------------------------------------
>
> Key: ARROW-10695
> URL: https://issues.apache.org/jira/browse/ARROW-10695
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Joris Van den Bossche
> Priority: Minor
> Labels: dataset, dataset-parquet-write
> Fix For: 5.0.0
>
>
> Currently we allow the user to specify a {{basename_template}}, and this can
> include a {{"\{i\}"}} part to replace it with an automatically incremented
> integer (so each generated file written to a single partition is unique):
> https://github.com/apache/arrow/blob/master/python/pyarrow/dataset.py#L713-L717
> It _might_ be useful to also have the ability to use a UUID, to ensure the
> file is unique in general (not only for a single write) and to mimic the
> behaviour of the old {{write_to_dataset}} implementation.
> For example, we could look for a {{"\{uuid\}"}} in the template string, and
> if present replace it for each file with a new UUID.
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