[jira] [Assigned] (KYLIN-4035) Calculate column cardinality by using spark engine

["Shaofeng SHI (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KYLIN-4035?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shaofeng SHI reassigned KYLIN-4035:
-----------------------------------

    Assignee: Jack

Hi Jack, thanks for the input and the PR. How about the performance improvement when switching from MR to Spark?

> Calculate column cardinality by using spark engine
> --------------------------------------------------
>
>                 Key: KYLIN-4035
>                 URL: https://issues.apache.org/jira/browse/KYLIN-4035
>             Project: Kylin
>          Issue Type: Improvement
>          Components: Spark Engine
>    Affects Versions: Future
>         Environment: kylin: master/3.0.0-alpha
> spark: 2.4.3
> hadoop: 2.6.5
>            Reporter: Jack
>            Assignee: Jack
>            Priority: Minor
>             Fix For: Future
>
>
> Kylin will calculate column cardinality when loading hive table. This stage is only supported by MR engine without spark. I think spark engine should be used in this stage because of the following:
> 1) Kylin users can choose which engine they apply when calculating column cardinality;
> 2) Some good spark features(e.g. dynamic resource allocation) can be used; 
> 3) The code written in spark is simple.
> I finish this work and test ok. But "kylin.engin.spark-cardinality=true" should be added in kylin.properties(default is false). Look forwards to suggestions.
> Best regards. 



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