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From "Xin Wu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SPARK-18727) Support schema evolution as new files are inserted into table
Date Thu, 27 Apr 2017 23:20:04 GMT

    [ https://issues.apache.org/jira/browse/SPARK-18727?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15987874#comment-15987874
] 

Xin Wu commented on SPARK-18727:
--------------------------------

[~ekhliang] First of all, i am not sure whether it is wise to introduce more non-SQL standard
syntax into Spark's DDL.  In addition, with ALTER TABLE SCHEMA, or ALTER TABLE SET/UPDATE/MOIDFY
SCHEMA, depending however we call it, it requires users to put in the whole list of columns'
definition for maybe a small change of a column. It is inconvenient especially when the table
is relatively wide. What do you think [~smilegator] ? 

> Support schema evolution as new files are inserted into table
> -------------------------------------------------------------
>
>                 Key: SPARK-18727
>                 URL: https://issues.apache.org/jira/browse/SPARK-18727
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.1.0
>            Reporter: Eric Liang
>            Priority: Critical
>
> Now that we have pushed partition management of all tables to the catalog, one issue
for scalable partition handling remains: handling schema updates.
> Currently, a schema update requires dropping and recreating the entire table, which does
not scale well with the size of the table.
> We should support updating the schema of the table, either via ALTER TABLE, or automatically
as new files with compatible schemas are appended into the table.
> cc [~rxin]



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