[jira] [Created] (HIVE-20007) Hive should carry out timestamp computations in UTC

["Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org>]

Jesus Camacho Rodriguez created HIVE-20007:
----------------------------------------------

             Summary: Hive should carry out timestamp computations in UTC
                 Key: HIVE-20007
                 URL: https://issues.apache.org/jira/browse/HIVE-20007
             Project: Hive
          Issue Type: Sub-task
          Components: Hive
            Reporter: Ryan Blue
            Assignee: Jesus Camacho Rodriguez
             Fix For: 3.1.0


Hive currently uses the "local" time of a java.sql.Timestamp to represent the SQL data type TIMESTAMP WITHOUT TIME ZONE. The purpose is to be able to use {{Timestamp#getYear()}} and similar methods to implement SQL functions like {{year}}.

When the SQL session's time zone is a DST zone, such as America/Los_Angeles that alternates between PST and PDT, there are times that cannot be represented because the effective zone skips them.

{code}
hive> select TIMESTAMP '2015-03-08 02:10:00.101';
2015-03-08 03:10:00.101
{code}

Using UTC instead of the SQL session time zone as the underlying zone for a java.sql.Timestamp avoids this bug, while still returning correct values for {{getYear}} etc. Using UTC as the convenience representation (timestamp without time zone has no real zone) would make timestamp calculations more consistent and avoid similar problems in the future.

Notably, this would break the {{unix_timestamp}} UDF that specifies the result is with respect to ["the default timezone and default locale"|https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF#LanguageManualUDF-DateFunctions]. That function would need to be updated to use the {{System.getProperty("user.timezone")}} zone.



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)