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https://issues.apache.org/jira/browse/HIVE-6439?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13902903#comment-13902903
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Brock Noland commented on HIVE-6439:
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Hi Laljo,
Essentially that is correct. The problem with that code is that it catches
Throwable and logs at debug. This means nasty errors such as OOM or internal
JVM errors which occur and will not be logged since most users do not log at
the debug level in production. I'd suggest not catching throwable and instead
catching exception. Catching exception is still a poor coding practice as you
will catch all kinds of runtime errors which you do not expect. I am guessing
the author is looking to "try CBO" and fail back if a bug is hit. Even in that
case, catching exception, we should be logging at a ERROR level unless there is
a very good reason not to.
> Introduce CBO step in Semantic Analyzer
> ---------------------------------------
>
> Key: HIVE-6439
> URL: https://issues.apache.org/jira/browse/HIVE-6439
> Project: Hive
> Issue Type: Sub-task
> Reporter: Harish Butani
> Assignee: Harish Butani
> Attachments: HIVE-6439.1.patch, HIVE-6439.2.patch
>
>
> This patch introduces CBO step in SemanticAnalyzer. For now the
> CostBasedOptimizer is an empty shell.
> The contract between SemAly and CBO is:
> - CBO step is controlled by the 'hive.enable.cbo.flag'.
> - When true Hive SemAly will hand CBO a Hive Operator tree (with operators
> annotated with stats). If it can CBO will return a better plan in Hive AST
> form.
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