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  1. Apache Arrow
  2. ARROW-1957

[Python] Write nanosecond timestamps using new NANO LogicalType Parquet unit

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    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 0.8.0
    • Fix Version/s: 0.14.0
    • Component/s: Python
    • Labels:
    • Environment:
      Python 3.6.4. Mac OSX and CentOS Linux release 7.3.1611. Pandas 0.21.1 .

      Description

      The following code

      import pyarrow as pa
      import pyarrow.parquet as pq
      import pandas as pd
      
      n=3
      df = pd.DataFrame({'x': range(n)}, index=pd.DatetimeIndex(start='2017-01-01', freq='1n', periods=n))
      pq.write_table(pa.Table.from_pandas(df), '/tmp/t.parquet')

      results in:

      ArrowInvalid: Casting from timestamp[ns] to timestamp[us] would lose data: 1483228800000000001

      The desired effect is that we can save nanosecond resolution without losing precision (e.g. conversion to ms). Note that if freq='1u' is used, the code runs properly.

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              • Assignee:
                tpboudreau TP Boudreau
                Reporter:
                jordansamuels Jordan Samuels
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                  Updated:
                  Resolved: