Thomas Li created ARROW-13471:
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Summary: [Python][Parquet]Pandas datetime columns not correctly
roundtripping with fastparquet(0.7.0) and pyarrow
Key: ARROW-13471
URL: https://issues.apache.org/jira/browse/ARROW-13471
Project: Apache Arrow
Issue Type: Bug
Components: Parquet, Python
Affects Versions: 4.0.1
Environment: pandas: 1.4.0.dev0+253.gedd5af779a.dirty
pyarrow: 4.0.1
fastparquet: 0.7.0
Reporter: Thomas Li
When trying to roundtrip data with pandas.read_parquet, datetime64[ns] columns
are not round-tripped correctly if the data is written with fastparquet and
read in with pyarrow. The data appears to be read in correctly, but the dtypes
are incorrect.
Note: This works correctly if the engine used to read and write is fastparquet.
I asked this on the fastparquet bug tracker and they said that it was a pyarrow
bug.
xref [Broken compat between fastparquet(0.7.0) and pyarrow · Issue #650 ·
dask/fastparquet (github.com)|https://github.com/dask/fastparquet/issues/650]
{code:java}
import pandas as pd
s = pd.DataFrame({"a":pd.date_range("20130101", periods=3)})
s.dtypes # datetime64[ns] s.to_parquet("test.parquet", engine="fastparquet")
pd.read_parquet("test.parquet", engine="pyarrow").dtypes
# datetime64[ns, UTC]
{code}
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