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https://issues.apache.org/jira/browse/HIVE-14251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15492297#comment-15492297
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Lefty Leverenz commented on HIVE-14251:
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Doc note: [~aihuaxu] documented this in the Union wikidoc.
* [Union -- Column Type Conversion |
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Union#LanguageManualUnion-ColumnTypeConversion]
Question: Should this also be mentioned in the section on implicit conversions
in the Data types doc?
* [Data Types -- Allowed Implicit Conversions |
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Types#LanguageManualTypes-AllowedImplicitConversions]
> Union All of different types resolves to incorrect data
> -------------------------------------------------------
>
> Key: HIVE-14251
> URL: https://issues.apache.org/jira/browse/HIVE-14251
> Project: Hive
> Issue Type: Bug
> Components: Query Planning
> Affects Versions: 2.0.0
> Reporter: Aihua Xu
> Assignee: Aihua Xu
> Fix For: 2.2.0
>
> Attachments: HIVE-14251.1.patch, HIVE-14251.2.patch,
> HIVE-14251.3.patch, HIVE-14251.4.patch, HIVE-14251.5.patch, HIVE-14251.6.patch
>
>
> create table src(c1 date, c2 int, c3 double);
> insert into src values ('2016-01-01',5,1.25);
> select * from
> (select c1 from src union all
> select c2 from src union all
> select c3 from src) t;
> It will return NULL for the c1 values. Seems the common data type is resolved
> to the last c3 which is double.
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