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https://issues.apache.org/jira/browse/HIVE-25293?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Work on HIVE-25293 started by yongtaoliao.
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> Alter partitioned table with "cascade" option create too many columns records.
> ------------------------------------------------------------------------------
>
> Key: HIVE-25293
> URL: https://issues.apache.org/jira/browse/HIVE-25293
> Project: Hive
> Issue Type: Improvement
> Components: Metastore
> Affects Versions: 2.3.3, 3.1.2
> Reporter: yongtaoliao
> Assignee: yongtaoliao
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> When alter partitioned table with "cascade" option, all partitions supports
> to be updated. Currently, a CD_ID will be created for each partition,
> associated with a set of Columns, which will cause a large amount of
> redundant data in the metadata database.
> The following DDL statements can reproduce this scenario：
>
> {code:java}
> create table test_table (f1 int) partitioned by (p string);
> alter table test_table add partition(p='a');
> alter table test_table add partition(p='b');
> alter table test_table add partition(p='c');
> alter table test_table add columns (f2 int) cascade;{code}
> All partitions use the table's `CD_ID` before adding columns, while each
> partition use their own `CD_ID` after adding columns.
>
> My proposal is all partitions should use the same `CD_ID` when table was
> altered with "cascade" option.
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