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https://issues.apache.org/jira/browse/TRAFODION-25?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14944932#comment-14944932
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ASF GitHub Bot commented on TRAFODION-25:
-----------------------------------------

Github user nonstop-qfchen commented on a diff in the pull request:

    https://github.com/apache/incubator-trafodion/pull/102#discussion_r41256153
  
    --- Diff: core/sql/optimizer/BindRelExpr.cpp ---
    @@ -11046,6 +11046,14 @@ RelExpr *MergeDelete::bindNode(BindWA *bindWA)
             bindWA->setErrStatus();
             return this;
           }
    +      if (CmpCommon::getDefault(COMP_BOOL_175) == DF_OFF)
    +      {
    +        // MERGE DELETE + INSERT is buggy, so disallow it unless CQD is 
on. In
    --- End diff --
    
    Since COMP_BOOL_175 is OFF by default, this check prevents MERGE_DELETE + 
INSERT.  Is it intended? 


> Insert, delete and update operators should use specialized cost method 
> -----------------------------------------------------------------------
>
>                 Key: TRAFODION-25
>                 URL: https://issues.apache.org/jira/browse/TRAFODION-25
>             Project: Apache Trafodion
>          Issue Type: Bug
>            Reporter: Qifan Chen
>            Assignee: David Wayne Birdsall
>              Labels: performance
>
> In Trafodion, insert, delete and update operators do not use a specialized 
> cost method that model the true operation involved. 
> As a result, these operators can be assigned a zero cost and the query plan 
> may not be optimal. In one example, a delete query against a partitioned 
> table may get a serial plan. 



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