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Posted to issues@hive.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2019/10/21 09:01:00 UTC
[jira] [Work logged] (HIVE-19653) Incorrect predicate pushdown for
groupby with grouping sets
[ https://issues.apache.org/jira/browse/HIVE-19653?focusedWorklogId=331291&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-331291 ]
ASF GitHub Bot logged work on HIVE-19653:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 21/Oct/19 09:00
Start Date: 21/Oct/19 09:00
Worklog Time Spent: 10m
Work Description: fan624009652 commented on issue #354: HIVE-19653: Incorrect predicate pushdown for groupby with grouping sets
URL: https://github.com/apache/hive/pull/354#issuecomment-544419803
Now I'm facing this problem and I wonder why this pull request is still unmerged.
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Issue Time Tracking
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Worklog Id: (was: 331291)
Remaining Estimate: 0h
Time Spent: 10m
> 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
> Reporter: Zhang Li
> Assignee: Zhang Li
> Priority: Major
> Labels: pull-request-available
> Fix For: 4.0.0
>
> Attachments: HIVE-19653.1.patch, HIVE-19653.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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