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https://issues.apache.org/jira/browse/HIVE-15530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15801500#comment-15801500
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Aihua Xu commented on HIVE-15530:
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Hey [~Yibing] I just took a brief look at the patch. In the new file you
created, you need to include the apache license header, which you can copy from
other files. And also, you don't need to include create time, your name and
contact in the file (I guess it's the convention?). Rather you can include the
comments to explain what the class does, etc.
> Optimize the column stats update logic in table alteration
> ----------------------------------------------------------
>
> Key: HIVE-15530
> URL: https://issues.apache.org/jira/browse/HIVE-15530
> Project: Hive
> Issue Type: Bug
> Components: Hive
> Reporter: Yibing Shi
> Assignee: Yibing Shi
> Attachments: HIVE-15530.1.patch, HIVE-15530.2.patch,
> HIVE-15530.3.patch
>
>
> Currently when a table is altered, if any of below conditions is true, HMS
> would try to update column statistics for the table:
> # database name is changed
> # table name is changed
> # old columns and new columns are not the same
> As a result, when a column is added to a table, Hive also tries to update
> column statistics, which is not necessary. We can loose the last condition by
> checking whether all existing columns are changed or not. If not, we don't
> have to update stats info.
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