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From "Daniel Voros (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SQOOP-3288) Incremental import's upper bound ignores session time zone in Oracle
Date Wed, 21 Feb 2018 14:50:00 GMT

    [ https://issues.apache.org/jira/browse/SQOOP-3288?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16371502#comment-16371502
] 

Daniel Voros commented on SQOOP-3288:
-------------------------------------

[~maugli] it's the other way around. We were getting the OS time before, that's what this
patch is supposed to fix. (Also, please note, that we were not relying on the time of the
OS running the sqoop job, but the OS running Oracle.)

> Incremental import's upper bound ignores session time zone in Oracle
> --------------------------------------------------------------------
>
>                 Key: SQOOP-3288
>                 URL: https://issues.apache.org/jira/browse/SQOOP-3288
>             Project: Sqoop
>          Issue Type: Bug
>          Components: connectors/oracle
>    Affects Versions: 1.4.7
>            Reporter: Daniel Voros
>            Assignee: Daniel Voros
>            Priority: Major
>             Fix For: 1.5.0
>
>         Attachments: SQOOP-3288.1.patch
>
>
> At the moment we're using [{{SELECT SYSDATE FROM dual}}|https://github.com/apache/sqoop/blob/3153c3610da7e5db388bfb14f3681d308e9e89c6/src/java/org/apache/sqoop/manager/OracleManager.java#L652]
when getting current time from Oracle.
> SYSDATE returns the underlying operating system's current time, while CURRENT_TIMESTAMP
uses the session time zone. This could lead to problems during incremental imports *when Oracle's
time zone is different from the OS*.
> Consider the following scenario when Oracle is configured to {{+0:00}}, while the OS
is {{+5:00}}:
> ||Oracle time||OS time||Event||
> |2:00|7:00|{{sqoop import --last-value 1:00 ...}} => imports {{[1:00, 7:00)}}|
> |2:30|7:30|{{update ... set last_updated = current_timestamp ...}} => set to {{2:30}}
*Won't be imported!*|
> |3:00|8:00|{{sqoop import --last-value 7:00 ...}} => imports {{[7:00, 8:00)}}|
> This way records updated within 5 hours after the last sqoop import won't get imported.
> Please note, that the example above assumes, that the user/administrator who's updating
the Oracle table will use the current session time of Oracle when setting the "last updated"
column of the table.
> I think the solution is to use CURRENT_TIMESTAMP instead of SYSDATE. Other connection
managers, like MySQL or PostgreSQL are using that as well.



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