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From "Varun Saxena (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-5585) [Atsv2] Add a new filter fromId in REST endpoints
Date Thu, 06 Oct 2016 15:01:20 GMT

    [ https://issues.apache.org/jira/browse/YARN-5585?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15552144#comment-15552144

Varun Saxena commented on YARN-5585:

bq. I was thinking to use same REST API for both by using SingleColumnFilter. One cons I see
is table scan for all the entityType i.e reflect in read performance.
We should not use SingleColumnValueFilter if we know the prefix because as you said former
will lead to a relatively slower read performance. Basically we need to differentiate between
having a prefix for the entity type and user unable to supply it.

bq. I would have thought that we store the entities in the reverse entity id order, but it
appears that the entity id is encoded into the row key as is (EntityRowKey). Am I reading
that right? If so, this is a bug to fix.
Entity IDs' can be anything. Even a completely alphabetical sequence can be an entity ID.
So it will not be possible to define a reverse order for every generic entity ID. Is this
your question ?

bq. Firstly about multi JVM which makes application programmer to define new protocol for
transferring prefixId. 
Trying to understand this more. Can same DAG be executed by multiple Tez AMs' ?

bq. Secondly, what if users misses providing an prefixId in subsequent updates.? 
This should be caught during integration phase. Right ?

> [Atsv2] Add a new filter fromId in REST endpoints
> -------------------------------------------------
>                 Key: YARN-5585
>                 URL: https://issues.apache.org/jira/browse/YARN-5585
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: timelinereader
>            Reporter: Rohith Sharma K S
>            Assignee: Rohith Sharma K S
>            Priority: Critical
>         Attachments: 0001-YARN-5585.patch, YARN-5585-workaround.patch, YARN-5585.v0.patch
> TimelineReader REST API's provides lot of filters to retrieve the applications. Along
with those, it would be good to add new filter i.e fromId so that entities can be retrieved
after the fromId. 
> Current Behavior : Default limit is set to 100. If there are 1000 entities then REST
call gives first/last 100 entities. How to retrieve next set of 100 entities i.e 101 to 200
OR 900 to 801?
> Example : If applications are stored database, app-1 app-2 ... app-10.
> *getApps?limit=5* gives app-1 to app-5. But to retrieve next 5 apps, there is no way
to achieve this. 
> So proposal is to have fromId in the filter like *getApps?limit=5&&fromId=app-5*
which gives list of apps from app-6 to app-10. 
> Since ATS is targeting large number of entities storage, it is very common use case to
get next set of entities using fromId rather than querying all the entites. This is very useful
for pagination in web UI.

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