[
https://issues.apache.org/jira/browse/HIVE-26779?focusedWorklogId=859122&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-859122
]
ASF GitHub Bot logged work on HIVE-26779:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 26/Apr/23 09:54
Start Date: 26/Apr/23 09:54
Worklog Time Spent: 10m
Work Description: kasakrisz opened a new pull request, #4272:
URL: https://github.com/apache/hive/pull/4272
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### What changes were proposed in this pull request?
`GenTezUtils.removeUnionOperators` tries to remove union operators from
union branches of the plan. I assume it is done because each branch has its own
Map vertex and the Union vertex takes the union of the result these.
Let's see the following query
```
SELECT NULL AS first_login_did
FROM tez_test_t5
LATERAL VIEW explode(split('0,6', ',')) gaps AS ads_h5_gap
UNION ALL
SELECT null as first_login_did
FROM tez_test_t1
UNION ALL
SELECT did AS first_login_did
FROM tez_test_t2
;
```
The plan before `removeUnionOperators`
```
TS[0]-LVF[1]-SEL[2] -LVJ[5]-SEL[6]-UNION[9]-SEL[12]-UNION[13]-FS[15]
-SEL[3]-UDTF[4]-LVJ[5]
TS[7]-SEL[8] -UNION[9]
TS[10]-SEL[11] -UNION[13]
```
The branch having lateral view has two sub branches from LVF (Lateral View
Forward op) to LVJ (Lateral View Join op).
The `removeUnionOperators` traverse the branches and it tries to remove the
UNION[9] operator twice. It fails the second time with the exception mentioned
in the jira.
### Why are the changes needed?
Fix issue mentioned above.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
```
mvn test -Dtest.output.overwrite -DskipSparkTests
-Dtest=TestMiniLlapLocalCliDriver -Dqfile=lateral_view_unionall.q -pl
itests/qtest -Pitests
```
Issue Time Tracking
-------------------
Worklog Id: (was: 859122)
Remaining Estimate: 0h
Time Spent: 10m
> UNION ALL throws SemanticException when trying to remove partition
> predicates: fail to find child from parent
> -------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-26779
> URL: https://issues.apache.org/jira/browse/HIVE-26779
> Project: Hive
> Issue Type: Bug
> Components: Query Processor
> Affects Versions: 4.0.0-alpha-2
> Reporter: Zhizhen Hou
> Assignee: Zhizhen Hou
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> {quote}Reproduce sql:
> drop table if exists tez_test_t1;
> create table tez_test_t1(md_exper string);
> insert into tez_test_t1 values('tez_test_t1-md_expr');
> drop table if exists tez_test_t5;
> create table tez_test_t5(md_exper string, did string);
> insert into tez_test_t5 values('tez_test_t5-md_expr','tez_test_t5-did');
> drop table if exists tez_test_t2;
> create table tez_test_t2(did string);
> insert into tez_test_t2 values('tez_test_t2-did');
> SELECT md_exper,null as ads_h5_gap , null as first_login_did, null as
> inclick_did
> FROM tez_test_t1
> UNION ALL
> SELECT md_exper, ads_h5_gap ,
> NULL AS first_login_did,did AS inclick_did
> FROM tez_test_t5
> LATERAL VIEW explode(split('0,6', ',')) gaps AS ads_h5_gap
> UNION ALL
> SELECT '' AS md_exper,'0,6' as ads_h5_gap ,
> did AS first_login_did, NULL AS inclick_did
> FROM tez_test_t2
> GROUP BY did;
> {quote}
>
> StackTrace
> 2022-11-27T09:31:06,801 ERROR [21d35a7f-9625-46ae-9c3d-13ca925f55cb main]:
> ql.Driver (:()) - FAILED: SemanticException Exception when trying to remove
> partition predicates: fail to find child from parent
> org.apache.hadoop.hive.ql.parse.SemanticException: Exception when trying to
> remove partition predicates: fail to find child from parent
> at
> org.apache.hadoop.hive.ql.exec.Operator.removeChildAndAdoptItsChildren(Operator.java:859)
> at
> org.apache.hadoop.hive.ql.parse.GenTezUtils.removeUnionOperators(GenTezUtils.java:348)
> at
> org.apache.hadoop.hive.ql.parse.TezCompiler.generateTaskTree(TezCompiler.java:573)
> at
> org.apache.hadoop.hive.ql.parse.TaskCompiler.compile(TaskCompiler.java:241)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.analyzeInternal(SemanticAnalyzer.java:12333)
> at
> org.apache.hadoop.hive.ql.parse.CalcitePlanner.analyzeInternal(CalcitePlanner.java:330)
> at
> org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:286)
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