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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