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From "Sangjin Lee (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-5814) Add druid as storage backend in YARN Timeline Service
Date Tue, 15 Nov 2016 22:39:58 GMT

    [ https://issues.apache.org/jira/browse/YARN-5814?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15668610#comment-15668610

Sangjin Lee commented on YARN-5814:

Thanks [~BINGXUE QIU] for adding more details. It sounds like a good starting point. A couple
of points.

It would be great to see some more details on the reader side of things. In the case of HBase/Phoenix,
more sophisticated analytical queries are going to be based on the Phoenix (SQL) schema. In
case of Druid, it would be interesting to see some examples being served right out of the
same schema.

Also, with readers we do a fair amount of predicate (filter) pushdown. We have the set of
timeline service filters which then get translated to HBase filters and are pushed down to
the queries. Have you looked at what kind of predicate pushdown would be feasible in case
of Druid?

I'd also like to bring your attention to the entity id prefix we just introduced (YARN-5715)
to solve the problem of more natural sort/selection order. The lexicographical sort order
based on the entity id's is going to fall short of the expectation, thus the reason for introducing
the entity id prefix. You might want to take a look at that, and see how that would translate
to the Druid schema.

I'll comment more if I have more things to think about.

>  Add druid as storage backend in YARN Timeline Service
> ------------------------------------------------------
>                 Key: YARN-5814
>                 URL: https://issues.apache.org/jira/browse/YARN-5814
>             Project: Hadoop YARN
>          Issue Type: New Feature
>          Components: ATSv2
>    Affects Versions: 3.0.0-alpha2
>            Reporter: Bingxue Qiu
>         Attachments: Add-Druid-in-YARN-Timeline-Service.pdf
> h3. Introduction
> I propose to add druid as storage backend in YARN Timeline Service.
> We run more than 6000 applications and generate 450 million metrics daily in Alibaba
Clusters with thousands of nodes. We need to collect and store meta/events/metrics data, online
analyze the utilization reports of various dimensions and display the trends of allocation/usage
resources for cluster by joining and aggregating data. It helps us to manage and optimize
the cluster by tracking resource utilization.
> To achieve our goal we have changed to use druid as the storage instead of HBase and
have achieved sub-second OLAP performance in our production environment for few months. 
> h3. Analysis
> Currently YARN Timeline Service only supports aggregating metrics at a) flow level by
FlowRunCoprocessor and b) application level metrics aggregating by AppLevelTimelineCollector,
offline (time-based periodic) aggregation for flows/users/queues for reporting and analysis
is planned but not yet implemented. YARN Timeline Service chooses Apache HBase as the primary
storage backend. As we all know that HBase doesn't fit for OLAP.
>  For arbitrary exploration of data,such as online analyze the utilization reports of
various dimensions(Queue,Flow,Users,Application,CPU,Memory) by joining and aggregating data,
Druid's custom column format enables ad-hoc queries without pre-computation. The format also
enables fast scans on columns, which is important for good aggregation performance.
> To achieve our goal that support to online analyze the utilization reports of various
dimensions, display the variation trends of allocation/usage resources for cluster, and arbitrary
exploration of data, we propose to add druid storage and implement DruidWriter /DruidReader
in YARN Timeline Service.

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