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https://issues.apache.org/jira/browse/IMPALA-5203?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Csaba Ringhofer resolved IMPALA-5203.
-------------------------------------
Resolution: Resolved
> from_utc_timestamp inconsistent how it handles daily savings time
> -----------------------------------------------------------------
>
> Key: IMPALA-5203
> URL: https://issues.apache.org/jira/browse/IMPALA-5203
> Project: IMPALA
> Issue Type: Bug
> Environment: Impala Shell v2.6.0-cdh5.8.3 (9872875) built on Fri Dec
> 9 14:31:00 PST 2016
> Reporter: Lou Bershad
> Priority: Major
>
> from_utc_timestamp(ts, EDT) as the timezone adjusts the time correctly
> whether or not the timestamp being translated was during daylight savings
> time. That is, it adjusts 4 hours for dates during daylight savings time and
> 5 hours for dates during standard time. from_utc_timetamp(ts, EST) always
> adjusts by 5 hours.
> In 2017, daylight savings time started on March 12th. This query shows that
> from_utc_timestamp using EDT adjusts 5 hours on March 11th and 4 hours on
> March 13th. When using EST, it adjusts 5 hours no matter what.
> {noformat}
> [i-pvd1c1mgr-vip.vldb-bo.secureworkslab.com:21001] > select 'EST',
> from_utc_timestamp('2017-03-11', 'EST'), from_utc_timestamp('2017-03-13',
> 'EST') ;
> Query: select 'EST', from_utc_timestamp('2017-03-11', 'EST'),
> from_utc_timestamp('2017-03-13', 'EST')
> +-------+-----------------------------------------+-----------------------------------------+
> | 'est' | from_utc_timestamp('2017-03-11', 'est') |
> from_utc_timestamp('2017-03-13', 'est') |
> +-------+-----------------------------------------+-----------------------------------------+
> | EST | 2017-03-10 19:00:00 | 2017-03-12 19:00:00
> |
> +-------+-----------------------------------------+-----------------------------------------+
> Fetched 1 row(s) in 0.01s
> [i-pvd1c1mgr-vip.vldb-bo.secureworkslab.com:21001] > select 'EST',
> from_utc_timestamp('2017-03-11', 'EDT'), from_utc_timestamp('2017-03-13',
> 'EDT') ;
> Query: select 'EST', from_utc_timestamp('2017-03-11', 'EDT'),
> from_utc_timestamp('2017-03-13', 'EDT')
> +-------+-----------------------------------------+-----------------------------------------+
> | 'est' | from_utc_timestamp('2017-03-11', 'edt') |
> from_utc_timestamp('2017-03-13', 'edt') |
> +-------+-----------------------------------------+-----------------------------------------+
> | EST | 2017-03-10 19:00:00 | 2017-03-12 20:00:00
> |
> +-------+-----------------------------------------+-----------------------------------------+
> Fetched 1 row(s) in 0.01s
> {noformat}
> The inconsistency could be fixed either by:
> # EST acts the same as EDT and adjusts the timestamp based on whether the
> timestamp is during daylight savings time. (I feel quite strongly that this
> would be the correct choice)
> # EDT always adjusts by 4 hours
> Note: The same dichotomy exists in other US timezones: PST/PDT, CST/CDT and
> MST/MDT. The dichotomy does not exist in France (CET/CEST).
> {noformat}
> Query: select tz, from_utc_timestamp('2017-03-01', tz),
> from_utc_timestamp('2017-05-01', tz) from (
> select 'EST' tz union all
> select 'EDT' tz union all
> select 'CST' tz union all
> select 'CDT' tz union all
> select 'PST' tz union all
> select 'PDT' tz union all
> select 'CET' tz union all
> select 'CEST' tz
> ) x
> +------+--------------------------------------+--------------------------------------+
> | tz | from_utc_timestamp('2017-03-01', tz) |
> from_utc_timestamp('2017-05-01', tz) |
> +------+--------------------------------------+--------------------------------------+
> | EST | 2017-02-28 19:00:00 | 2017-04-30 19:00:00
> |
> | EDT | 2017-02-28 19:00:00 | 2017-04-30 20:00:00
> |
> | CST | 2017-02-28 18:00:00 | 2017-04-30 19:00:00
> |
> | CDT | 2017-02-28 18:00:00 | 2017-04-30 19:00:00
> |
> | PST | 2017-02-28 16:00:00 | 2017-04-30 17:00:00
> |
> | PDT | 2017-02-28 16:00:00 | 2017-04-30 17:00:00
> |
> | CET | 2017-03-01 01:00:00 | 2017-05-01 02:00:00
> |
> | CEST | 2017-03-01 01:00:00 | 2017-05-01 02:00:00
> |
> +------+--------------------------------------+--------------------------------------+
> Fetched 8 row(s) in 0.02s
> {noformat}
>
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