[jira] [Created] (ARROW-7782) Losing index information when using write_to_dataset with partition_cols

2020-02-06 Thread Ludwik Bielczynski (Jira)
Ludwik Bielczynski created ARROW-7782:
-

 Summary: Losing index information when using write_to_dataset with 
partition_cols
 Key: ARROW-7782
 URL: https://issues.apache.org/jira/browse/ARROW-7782
 Project: Apache Arrow
  Issue Type: Bug
 Environment: pyarrow==0.15.1
Reporter: Ludwik Bielczynski


One cannot save the index when using {{pyarrow.parquet.write_to_dataset()}} 
with given partition_cols arguments. Here I have created a minimal example 
which shows the issue:
{code:java}
 
from pathlib import Path
import pandas as pd
from pyarrow import Table
from pyarrow.parquet import write_to_dataset
path = Path('/home/ludwik/Documents/YieldPlanet/research/trials')
file_name = 'trial_pq.parquet'
df = pd.DataFrame({"A": [1, 2, 3], 
 "B": ['a', 'a', 'b']
 }, 
 index=pd.Index(['a', 'b', 'c'], name='idx'))

table = Table.from_pandas(df)
write_to_dataset(table, str(path / file_name), partition_cols=['B'],
 partition_filename_cb=None, filesystem=None)
{code}
 

The issue is rather important for pandas and dask users.



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[jira] [Created] (ARROW-1398) No support reading columns of type decimal(19,4)

2017-08-22 Thread Ludwik Bielczynski (JIRA)
Ludwik Bielczynski created ARROW-1398:
-

 Summary: No support reading columns of type decimal(19,4)
 Key: ARROW-1398
 URL: https://issues.apache.org/jira/browse/ARROW-1398
 Project: Apache Arrow
  Issue Type: Bug
  Components: Python
Affects Versions: 0.6.0
 Environment: Ubuntu 16.04, Python 3.6
Reporter: Ludwik Bielczynski


I have a localy saved parquet database created in spark from querrying an SQL 
database. When I run:

{code:python}
import pyarrow.parquet as pq

path = "path/to/parquet/dataset"
dataset = pq.ParquetDataset(path)
dataset.read()
{code}

an error indicating that there is no support for reading columns of type 
decimal(19,4). It's quite a common type used in SQL databases and I saw in the 
source code that there is an implementation for decimals. I'm stuck trying to 
figuring out a solution. Is there a walk around (conversion of decimals to 
integers during reading)?



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