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From "Hari Sankar Sivarama Subramaniyan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-12640) Allow StatsOptimizer to optimize the query for Constant GroupBy keys
Date Thu, 10 Dec 2015 21:02:11 GMT

     [ https://issues.apache.org/jira/browse/HIVE-12640?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Hari Sankar Sivarama Subramaniyan updated HIVE-12640:
-----------------------------------------------------
    Description: 
{code}
hive> select count('1') from src group by '1';
{code}

In the above query, while performing StatsOptimizer optimization we can safely ignore the
group by on the constant key '1' since the above query will return the same result as "select
count('1') from src".

Exception:
If src is empty, according to the SQL standard, should
 select count('1') from src group by '1'
and
 select count('1') from src

  was:
{code}
hive> select count('1') from src group by '1';
{code}

In the above query, while performing StatsOptimizer optimization we can safely ignore the
group by on the constant key '1' since the above query will return the same result as "select
count('1') from src".


> Allow StatsOptimizer to optimize the query for Constant GroupBy keys 
> ---------------------------------------------------------------------
>
>                 Key: HIVE-12640
>                 URL: https://issues.apache.org/jira/browse/HIVE-12640
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Hari Sankar Sivarama Subramaniyan
>            Assignee: Hari Sankar Sivarama Subramaniyan
>         Attachments: HIVE-12640.1.patch
>
>
> {code}
> hive> select count('1') from src group by '1';
> {code}
> In the above query, while performing StatsOptimizer optimization we can safely ignore
the group by on the constant key '1' since the above query will return the same result as
"select count('1') from src".
> Exception:
> If src is empty, according to the SQL standard, should
>  select count('1') from src group by '1'
> and
>  select count('1') from src



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