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https://issues.apache.org/jira/browse/PARQUET-200?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14551089#comment-14551089
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Ryan Blue commented on PARQUET-200:
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I just updated this for microsecond instead of nanosecond types. SQL requires
microseconds, and most nanosecond times aren't accurate enough to be valuable.
Impala intends to move away from nanosecond precision and this proposal is now
in line with the microsecond types we removed from the PR when we added
millisecond time types.
> Add microsecond time and timestamp annotations
> ----------------------------------------------
>
> Key: PARQUET-200
> URL: https://issues.apache.org/jira/browse/PARQUET-200
> Project: Parquet
> Issue Type: Improvement
> Components: parquet-format
> Reporter: Ryan Blue
>
> When the date/time type annotations were added, we decided not to add
> precisions smaller than milliseconds because there wasn't a clear
> requirement. I think that the requirement is for nanosecond precision. The
> SQL spec requires at least microsecond. Some databases support nanosecond,
> including SQL engines on Hadoop like Phoenix. Hive and Impala currently
> support nanosecond times using an int96, but intend to move to microsecond
> precision with this spec.
> I propose adding the following type annotations:
> * {{TIME_MICROS}}: annotates an int64 (8 bytes), represents the number of
> microseconds from midnight.
> * {{TIMESTAMP_MICROS}}: annotates an int64 (8 bytes), represents the number
> of microseconds from the unix epoch.
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