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https://issues.apache.org/jira/browse/HIVE-17460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16156233#comment-16156233
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Matt McCline commented on HIVE-17460:
-------------------------------------
I don't think this is right -- you will end up with upset customers because
query results will be different.
Unfortunately, the current semantics of adding a column are that the default
behavior is RESTRICT not CASCADE. RESTRICT means the partition schema's do not
get updated with the new columns. Thus, the new columns default to NULL when
queried. In order to get the behavior you are talking about you would need to
specify the CASCADE option.
So I'm a -1 on this change.
[~wzheng]
> `insert overwrite` should support table schema evolution (e.g. add columns)
> ---------------------------------------------------------------------------
>
> Key: HIVE-17460
> URL: https://issues.apache.org/jira/browse/HIVE-17460
> Project: Hive
> Issue Type: Bug
> Affects Versions: 2.1.0, 2.2.0
> Reporter: Chaozhong Yang
> Assignee: Chaozhong Yang
> Fix For: 3.0.0
>
> Attachments: HIVE-17460.2.patch, HIVE-17460.patch
>
>
> In Hive, adding columns into original table is a common use case. However, if
> we insert overwrite older partitions after adding columns, added columns will
> not be accessed.
> ```
> create table src_table(
> i int
> )
> PARTITIONED BY (`date` string);
> insert overwrite table src_table partition(`date`='20170905') valu
> es (3);
> select * from src_table where `date` = '20170905';
> alter table src_table add columns (bi bigint);
> insert overwrite table src_table partition(`date`='20170905') valu
> es (3, 5);
> select * from src_table where `date` = '20170905';
> ```
> The result will be as follows:
> ```
> 3, NULL, '20170905'
> ```
> Obviously, it doesn't meet our expectation. The expected result should be:
> ```
> 3, 5, '20170905'
> ```
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