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Posted to issues@arrow.apache.org by "Ben Kietzman (Jira)" <ji...@apache.org> on 2020/05/14 20:47:00 UTC
[jira] [Assigned] (ARROW-8729) [C++][Dataset] Only selecting a
partition column results in empty table
[ https://issues.apache.org/jira/browse/ARROW-8729?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Ben Kietzman reassigned ARROW-8729:
-----------------------------------
Assignee: Ben Kietzman
> [C++][Dataset] Only selecting a partition column results in empty table
> -----------------------------------------------------------------------
>
> Key: ARROW-8729
> URL: https://issues.apache.org/jira/browse/ARROW-8729
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
> Reporter: Joris Van den Bossche
> Assignee: Ben Kietzman
> Priority: Major
> Labels: dataset
> Fix For: 1.0.0
>
>
> Python reproducer:
> {code}
> import pyarrow as pa
> import pyarrow.parquet as pq
> import pyarrow.dataset as ds
> path = "test_dataset"
> table = pa.table({'part': ['a', 'a', 'b', 'b'], 'col': [1, 2, 3, 4]})
> pq.write_to_dataset(table, str(path), partition_cols=["part"])
> {code}
> gives
> {code}
> In [38]: ds.dataset(str(path), partitioning="hive").to_table().num_rows
> Out[38]: 4
> In [39]: ds.dataset(str(path), partitioning="hive").to_table(columns=["part"]).num_rows
> Out[39]: 0
> {code}
> The schema correctly only includes the "part" column, but there are no rows.
> cc [~bkietz]
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