[jira] [Commented] (LENS-40) Final Explan plan returned should include more information on why drivers are skipped

["Ajay Yadava (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LENS-40?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15212218#comment-15212218 ] 

Ajay Yadava commented on LENS-40:
---------------------------------

Here is my understanding followed by the approaches that I am considering.

Use case scenario: Users fire a query and expect certain low cost drivers to be selected but for some reasons (data not available etc.) another driver gets selected. We would like to be able to debug such scenarios.

Approach 1: Log the {code}LensException cause{code} in {code}QueryExecutionServiceImpl::RewriteEstimateRunnable{code} 

Approach 2: Change QueryPlan class to store drivers and the reasons the exceptions / cost. Will need to populate this in {code}QueryExecutionServiceImpl.java:explain{code} and {code}QueryExecutionServiceImpl.java:explainAndPrepare{code} methods.

Please provide your inputs.

> Final Explan plan returned should include more information on why drivers are skipped
> -------------------------------------------------------------------------------------
>
>                 Key: LENS-40
>                 URL: https://issues.apache.org/jira/browse/LENS-40
>             Project: Apache Lens
>          Issue Type: Improvement
>          Components: server
>            Reporter: Amareshwari Sriramadasu
>            Assignee: Ajay Yadava
>              Labels: newbie
>
> When we do explain with multiple drivers in server and choose one, we should include the reason why other drivers are skipped.
> This would help users improve their query if the query is going to different execution engine than they expected.



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