Dask

How to install

Dask also supports Apache ORC.

pip3 install "dask[dataframe]==2025.5.1"
pip3 install pandas

How to write and read an ORC file

In [1]: import pandas as pd

In [2]: import dask.dataframe as dd

In [3]: pf = pd.DataFrame(data={"col1": [1, 2, 3], "col2": ["a", "b", None]})

In [4]: dd.to_orc(dd.from_pandas(pf, npartitions=2), path="/tmp/orc")
Out[4]: (None, None)

In [5]: dd.read_orc(path="/tmp/orc").compute()
Out[5]:
   col1  col2
0     1     a
1     2     b
0     3  <NA>

In [6]: dd.read_orc(path="/tmp/orc", columns=["col1"]).compute()
Out[6]:
   col1
0     1
1     2
0     3

10 Minutes to Dask page provides a short overview.

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