[jira] [Commented] (HIVE-14256) CBO: Rewrite aggregate + distinct as 3-stage DAG

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

    [ https://issues.apache.org/jira/browse/HIVE-14256?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15380401#comment-15380401 ] 

Ashutosh Chauhan commented on HIVE-14256:
-----------------------------------------

set hive.optimize.distinct.rewrite=true ?

> CBO: Rewrite aggregate + distinct as 3-stage DAG
> ------------------------------------------------
>
>                 Key: HIVE-14256
>                 URL: https://issues.apache.org/jira/browse/HIVE-14256
>             Project: Hive
>          Issue Type: Improvement
>          Components: CBO
>    Affects Versions: 2.2.0
>            Reporter: Gopal V
>
> {code}
> select sum(ss_net_profit), count(distinct ss_customer_sk) from store_sales;
> {code}
> is very slow, while manually sub-aggregating this makes it much faster.
> {code}
> select sum(v), count(c) from 
> ( select sum(ss_net_profit) as v, ss_customer_sk as k from store_sales group by ss_customer_sk);
> {code}
> Query28 in TPC-DS would be an example of whether this would be valuable.



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