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From "Varun Saxena (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-4178) [storage implementation] app id as string can cause incorrect ordering
Date Mon, 28 Sep 2015 15:57:05 GMT

    [ https://issues.apache.org/jira/browse/YARN-4178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14933487#comment-14933487

Varun Saxena commented on YARN-4178:

After giving some further thought over it, in the patch, I have not stored application_ in
the row key and using ApplicationId for conversion.
The reason is same as above. ApplicationId class is used across YARN to represent app id.
Any change in app id format would reflect in this class too.
If we do not use this class, we have to write our own custom conversion method and from maintenance
point of view, any future changes in app id format may be missed here.
If we really want to store application_ part due to the example given by Joep, maybe we can
add a method in ApplicationId which takes in prefix as an additional parameter instead of
taking it from static field. 
Thoughts ?

Also, if we follow approach in the patch, conversion to ApplicationId from string can be done
while filling the context itself. But as we need to refactor reader code and  have common
context for reader and writer, we can do this later.

> [storage implementation] app id as string can cause incorrect ordering
> ----------------------------------------------------------------------
>                 Key: YARN-4178
>                 URL: https://issues.apache.org/jira/browse/YARN-4178
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: timelineserver
>    Affects Versions: YARN-2928
>            Reporter: Sangjin Lee
>            Assignee: Varun Saxena
>         Attachments: YARN-4178-YARN-2928.01.patch
> Currently the app id is used in various places as part of row keys and in column names.
However, they are treated as strings for the most part. This will cause a problem with ordering
when the id portion of the app id rolls over to the next digit.
> For example, "app_1234567890_100" will be considered *earlier* than "app_1234567890_99".
We should correct this.

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