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https://issues.apache.org/jira/browse/HIVE-2747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13199099#comment-13199099
]
Namit Jain commented on HIVE-2747:
----------------------------------
create table tmp_tx1 (key string, value string);
insert overwrite table tmp_tx1 select * from src where key < 10;
create table tmp_tx2 (key int, value string);
insert overwrite table tmp_tx2 select * from src where key < 10;
select * from
(
select key, count(1) from tmp_tx1 group by key
union all
select key, count(1) from tmp_tx2 group by key
)
u;
The above also fails. Basically, if the types of the union dont match, we get a
run-time error.
The query:
select * from
(
select key, count(1) from tmp_tx1 group by key
union all
select cast(key as string) as key, count(1) from tmp_tx2 group by key
)
u;
works fine
> UNION ALL with subquery which selects NULL and performs group by fails
> ----------------------------------------------------------------------
>
> Key: HIVE-2747
> URL: https://issues.apache.org/jira/browse/HIVE-2747
> Project: Hive
> Issue Type: Bug
> Reporter: Kevin Wilfong
> Assignee: Kevin Wilfong
>
> Queries like the following
> from (select key, value, count(1) as count from src group by key, value union
> all select NULL as key, value, count(1) as count from src group by value) a
> select count(*);
> fail with the exception
> java.lang.NullPointerException
> at
> org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector.toString(StructObjectInspector.java:60)
> at java.lang.String.valueOf(String.java:2826)
> at java.lang.StringBuilder.append(StringBuilder.java:115)
> at
> org.apache.hadoop.hive.ql.exec.UnionOperator.initializeOp(UnionOperator.java:110)
> at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:357)
> at
> org.apache.hadoop.hive.ql.exec.MapOperator.initializeOp(MapOperator.java:427)
> at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:357)
> at org.apache.hadoop.hive.ql.exec.ExecMapper.configure(ExecMapper.java:98)
> ... 18 more
> This should at least provide a more informative error message if not work.
> It works without the group by.
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