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https://issues.apache.org/jira/browse/HIVE-19653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16492920#comment-16492920
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Ashutosh Chauhan commented on HIVE-19653:
-----------------------------------------

TestMiniLlapLocalCliDriver.testCliDriver[vector_groupby_grouping_sets4] is 
failing with:
{code}
Caused by: java.lang.NullPointerException
        at 
org.apache.hadoop.hive.ql.plan.AggregationDesc.getExprString(AggregationDesc.java:153)
        at 
org.apache.hadoop.hive.ql.plan.GroupByDesc.getAggregatorStrings(GroupByDesc.java:217)
        ... 82 more

{code}

> Incorrect predicate pushdown for groupby with grouping sets
> -----------------------------------------------------------
>
>                 Key: HIVE-19653
>                 URL: https://issues.apache.org/jira/browse/HIVE-19653
>             Project: Hive
>          Issue Type: Bug
>          Components: Logical Optimizer
>    Affects Versions: 4.0.0
>            Reporter: Zhang Li
>            Assignee: Zhang Li
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 4.0.0
>
>         Attachments: HIVE-19653.patch
>
>
> Consider the following query:
> {code:java}
> CREATE TABLE T1(a STRING, b STRING, s BIGINT);
> INSERT OVERWRITE TABLE T1 VALUES ('aaaa', 'bbbb', 123456);
> SELECT * FROM (
> SELECT a, b, sum(s)
> FROM T1
> GROUP BY a, b GROUPING SETS ((), (a), (b), (a, b))
> ) t WHERE a IS NOT NULL;
> {code}
> When hive.optimize.ppd is enabled (and hive.cbo.enable=false), the query will 
> output:
> {code:java}
> NULL  NULL    123456
> NULL  bbbb    123456
> aaaa  NULL    123456
> aaaa  bbbb    123456
> {code}
> We can see the predicate "a IS NOT NULL" takes no effect, which is incorrect.
> When performing PPD optimization for a GBY operator, we should make sure all 
> grouping sets contains the processing expr before pushdown. otherwise the 
> expr value after GBY is changed and the result is wrong.



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