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https://issues.apache.org/jira/browse/YARN-4178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14804414#comment-14804414
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Varun Saxena commented on YARN-4178:
------------------------------------

ApplicationId is basically a combination of cluster timestamp and a 
monotonically increasing sequence number/id. 
We can hence store application id as a sequence of 2 longs or 2 ints in the row 
key to ensure order is maintained.

We can encode it on the way in and decode it as a string on the way out by 
using ApplicationId#toString.

We are however storing app attempts ids and container ids in the same way. They 
will go into the entity table.



> [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
>
> 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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