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https://issues.apache.org/jira/browse/HIVE-19653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16492913#comment-16492913
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Ashutosh Chauhan commented on HIVE-19653:
-----------------------------------------
+1
> 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
> 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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