[jira] [Assigned] (HIVE-25046) Log CBO plans right after major transformations

["Stamatis Zampetakis (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-25046?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stamatis Zampetakis reassigned HIVE-25046:
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> Log CBO plans right after major transformations
> -----------------------------------------------
>
>                 Key: HIVE-25046
>                 URL: https://issues.apache.org/jira/browse/HIVE-25046
>             Project: Hive
>          Issue Type: Improvement
>          Components: CBO
>            Reporter: Stamatis Zampetakis
>            Assignee: Stamatis Zampetakis
>            Priority: Major
>
> Currently the results of various CBO transformations are logged (in DEBUG mode) at the end of the optimization [phase|https://github.com/apache/hive/blob/9f5bd72e908244b2fe915e8dc39f55afa94bbffa/ql/src/java/org/apache/hadoop/hive/ql/parse/CalcitePlanner.java#L2106] and only if we are not in test mode. This has some disadvantages:
> * If there is a failure (exception) in some intermediate step we will miss all the intermediate  plans, possibly losing track of what plan led to the problem.
> * Intermediate logs are very useful for identifying plan problems while working on a patch; unfortunately the logs are explicitly disabled in test mode which means that in order to appear the respective code needs to change every time we need to see those logs.
> * Logging at the end necessitates keeping additional local variables that make code harder to read.
> The goal of this issue is to place DEBUG logging right after major transformations and independently if we are running in test mode or not to alleviate the shortcomings mentioned above.



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