[jira] [Created] (HIVE-19653) Incorrect predicate pushdown for groupby with grouping sets

["Zhang Li (JIRA)" <ji...@apache.org>]

Zhang Li created HIVE-19653:
-------------------------------

             Summary: 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: 3.1.0
            Reporter: Zhang Li
            Assignee: Zhang Li
             Fix For: 3.1.0


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), (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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