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From "Brock Noland (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-6439) Introduce CBO step in Semantic Analyzer
Date Sat, 15 Feb 2014 22:46:19 GMT

    [ https://issues.apache.org/jira/browse/HIVE-6439?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13902557#comment-13902557
] 

Brock Noland commented on HIVE-6439:
------------------------------------

1) There are many tabs and spacing issues in this patch
2) We are catching throwable and logging at debug. We should *never* do this.

{noformat}
} catch (Throwable t) {
LOG.debug("CBO failed, skipping CBO", t);
{noformat}

> 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
>
>
> 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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