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https://issues.apache.org/jira/browse/HIVE-13452?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15677507#comment-15677507
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Vineet Garg commented on HIVE-13452:
------------------------------------
With postgres
{code}
select count(*) from tempty group by (1=1) ; --tempty is an empty table
count
-------
(0 rows)
{code}
So as [~ashutoshc] suggested for count(*) with group by 1 on an empty table
should not return any row
> StatsOptimizer should return no rows on empty table with group by
> -----------------------------------------------------------------
>
> Key: HIVE-13452
> URL: https://issues.apache.org/jira/browse/HIVE-13452
> Project: Hive
> Issue Type: Bug
> Components: Logical Optimizer
> Reporter: Ashutosh Chauhan
> Assignee: Pengcheng Xiong
>
> {code}
> create table t1 (a int);
> analyze table t1 compute statistics;
> analyze table t1 compute statistics for columns;
> select count(1) from t1 group by 1;
> set hive.compute.query.using.stats=true;
> select count(1) from t1 group by 1;
> {code}
> In both cases result set should be empty. However, with statsoptimizer on
> Hive returns one row with value 0.
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