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https://issues.apache.org/jira/browse/HIVE-14251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15386026#comment-15386026
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Aihua Xu commented on HIVE-14251:
---------------------------------
Yeah. Actually implicitConvertible() is not completely accurate I feel. I just
put the comment why I try to avoid reusing the same function.
So for comparison of string and double, then we should compare them in double
type. That's implicitConvertible() is trying to do, returning true for string
=> double conversion.
I feel comparison and union do need separate functions though.
> 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
> Attachments: HIVE-14251.1.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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