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From "Rui Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-14305) To/From UTC timestamp may return incorrect result because of DST
Date Mon, 25 Jul 2016 02:23:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-14305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15391260#comment-15391260
] 

Rui Li commented on HIVE-14305:
-------------------------------

[~rdblue], I think that effectively requires us to set UTC as default timezone throughout
the whole query. IIUC, Timestamp is a wrapper of Date plus nano second info. If we want the
computation performed in UTC, we need to call {{Timezone.setDefault}} to set default timezone.
This method is JVM-wide and not thread safe, which means we cannot set UTC for specific computation
and then switch back to system default timezone.
Not sure if this is acceptable. Also pinging [~xuefuz], [~szehon], [~sershe] for opinions.

> To/From UTC timestamp may return incorrect result because of DST
> ----------------------------------------------------------------
>
>                 Key: HIVE-14305
>                 URL: https://issues.apache.org/jira/browse/HIVE-14305
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Rui Li
>            Assignee: Rui Li
>
> If the machine's local timezone involves DST, the UDFs return incorrect results.
> For example:
> {code}
> select to_utc_timestamp('2005-04-03 02:01:00','UTC');
> {code}
> returns {{2005-04-03 03:01:00}}. Correct result should be {{2005-04-03 02:01:00}}.
> {code}
> select to_utc_timestamp('2005-04-03 10:01:00','Asia/Shanghai');
> {code}
> returns {{2005-04-03 03:01:00}}. Correct result should be {{2005-04-03 02:01:00}}.



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