Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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0.8.0
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OS: Mac OS X 10.13.2
Python: 3.6.4
PyArrow: 0.8.0
Description
When writing to a Parquet file, if `use_deprecated_int96_timestamps` is True, timestamps are only written as 96-bit integers if the timestamp has nanosecond resolution. This is a problem because Amazon Redshift timestamps only have microsecond resolution but require them to be stored in 96-bit format in Parquet files.
I'd expect the use_deprecated_int96_timestamps flag to cause all timestamps to be written as 96 bits, regardless of resolution. If this is a deliberate design decision, it'd be immensely helpful if it were explicitly documented as part of the argument.
To reproduce:
1. Create a table with a timestamp having microsecond or millisecond resolution, and save it to a Parquet file. Be sure to set `use_deprecated_int96_timestamps` to True.
import datetime import pyarrow from pyarrow import parquet schema = pyarrow.schema([ pyarrow.field('last_updated', pyarrow.timestamp('us')), ]) data = [ pyarrow.array([datetime.datetime.now()], pyarrow.timestamp('us')), ] table = pyarrow.Table.from_arrays(data, ['last_updated']) with open('test_file.parquet', 'wb') as fdesc: parquet.write_table(table, fdesc, use_deprecated_int96_timestamps=True)
2. Inspect the file. I used parquet-tools:
dak@tux ~ $ parquet-tools meta test_file.parquet file: file:/Users/dak/test_file.parquet creator: parquet-cpp version 1.3.2-SNAPSHOT file schema: schema -------------------------------------------------------------------------------- last_updated: OPTIONAL INT64 O:TIMESTAMP_MICROS R:0 D:1 row group 1: RC:1 TS:76 OFFSET:4 -------------------------------------------------------------------------------- last_updated: INT64 SNAPPY DO:4 FPO:28 SZ:76/72/0.95 VC:1 ENC:PLAIN,PLAIN_DICTIONARY,RLE
Attachments
Issue Links
- relates to
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ARROW-1957 [Python] Write nanosecond timestamps using new NANO LogicalType Parquet unit
- Resolved
- links to