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https://issues.apache.org/jira/browse/HIVE-14903?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15551569#comment-15551569
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Eric Lin commented on HIVE-14903:
---------------------------------

Both Hive and Impala seem to have the issue, so also created 
https://issues.cloudera.org/browse/IMPALA-4250

> from_utc_time function issue for CET daylight savings
> -----------------------------------------------------
>
>                 Key: HIVE-14903
>                 URL: https://issues.apache.org/jira/browse/HIVE-14903
>             Project: Hive
>          Issue Type: Bug
>          Components: Beeline
>    Affects Versions: 2.0.1
>            Reporter: Eric Lin
>            Priority: Minor
>
> Based on https://en.wikipedia.org/wiki/Central_European_Summer_Time, the 
> summer time is between 1:00 UTC on the last Sunday of March and 1:00 on the 
> last Sunday of October, see test case below:
> Impala:
> {code}
> select from_utc_timestamp('2016-10-30 00:30:00','CET');
> Query: select from_utc_timestamp('2016-10-30 00:30:00','CET')
> +--------------------------------------------------+
> | from_utc_timestamp('2016-10-30 00:30:00', 'cet') |
> +--------------------------------------------------+
> | 2016-10-30 01:30:00                              |
> +--------------------------------------------------+
> {code}
> Hive:
> {code}
> select from_utc_timestamp('2016-10-30 00:30:00','CET');
> INFO  : OK
> +------------------------+--+
> |          _c0           |
> +------------------------+--+
> | 2016-10-30 01:30:00.0  |
> +------------------------+--+
> {code}
> MySQL:
> {code}
> mysql> SELECT CONVERT_TZ( '2016-10-30 00:30:00', 'UTC', 'CET' );
> +---------------------------------------------------+
> | CONVERT_TZ( '2016-10-30 00:30:00', 'UTC', 'CET' ) |
> +---------------------------------------------------+
> | 2016-10-30 02:30:00                               |
> +---------------------------------------------------+
> {code}
> At 00:30AM UTC, the daylight saving has not finished so the time different 
> should still be 2 hours rather than 1. MySQL returned correct result
> At 1:30, results are correct:
> Impala:
> {code}
> Query: select from_utc_timestamp('2016-10-30 01:30:00','CET')
> +--------------------------------------------------+
> | from_utc_timestamp('2016-10-30 01:30:00', 'cet') |
> +--------------------------------------------------+
> | 2016-10-30 02:30:00                              |
> +--------------------------------------------------+
> Fetched 1 row(s) in 0.01s
> {code}
> Hive:
> {code}
> +------------------------+--+
> |          _c0           |
> +------------------------+--+
> | 2016-10-30 02:30:00.0  |
> +------------------------+--+
> 1 row selected (0.252 seconds)
> {code}
> MySQL:
> {code}
> mysql> SELECT CONVERT_TZ( '2016-10-30 01:30:00', 'UTC', 'CET' );
> +---------------------------------------------------+
> | CONVERT_TZ( '2016-10-30 01:30:00', 'UTC', 'CET' ) |
> +---------------------------------------------------+
> | 2016-10-30 02:30:00                               |
> +---------------------------------------------------+
> 1 row in set (0.00 sec)
> {code}
> Seems like a bug.



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