[jira] [Commented] (HIVE-12866) Allow ReduceSinkDeDuplication to kick in when there are constant keys

["Ashutosh Chauhan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-12866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15270517#comment-15270517 ] 

Ashutosh Chauhan commented on HIVE-12866:
-----------------------------------------

We have entirely disabled RS-dedup in presence of constants, it will be nice if we can restore this optimization.

> Allow ReduceSinkDeDuplication to kick in when there are constant keys 
> ----------------------------------------------------------------------
>
>                 Key: HIVE-12866
>                 URL: https://issues.apache.org/jira/browse/HIVE-12866
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Hari Sankar Sivarama Subramaniyan
>
> Currently in ReduceSinkDeDuplication.checkExprs() we have the following check which prevents the optimization from kicking in as soon as we hit constant key. We should lift this restriction as much as possible.
> {code}
>     private Integer checkExprs(List<ExprNodeDesc> ckeys, List<ExprNodeDesc> pkeys,
>         ReduceSinkOperator cRS, ReduceSinkOperator pRS) throws SemanticException {
>       // If ckeys or pkeys have constant node expressions avoid the merge.
>       for (ExprNodeDesc ck : ckeys) {
>         if (ck instanceof ExprNodeConstantDesc) {
>           return null;
>         }
>       }
>       for (ExprNodeDesc pk : pkeys) {
>         if (pk instanceof ExprNodeConstantDesc) {
>           return null;
>         }
>       }
> {code}



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