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https://issues.apache.org/jira/browse/HIVE-7046?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13995384#comment-13995384
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Szehon Ho commented on HIVE-7046:
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This is also related to HIVE-6131
> Propagate addition of new columns to partition schema
> -----------------------------------------------------
>
> Key: HIVE-7046
> URL: https://issues.apache.org/jira/browse/HIVE-7046
> Project: Hive
> Issue Type: Improvement
> Components: Database/Schema
> Affects Versions: 0.12.0
> Reporter: Mariano Dominguez
>
> Hive reads data according to the partition schema, not the table schema
> (because of HIVE-3833). ALTER TABLE only updates the table schema, and the
> changes are not propagated to partitions. Thus, the schema of a partition
> will differ from that of the table after altering the table schema; this is
> done to preserve the ability to read existing data, particularly when using
> binary formats such as RCFile. Binary formats do not allow changing the type
> of a field because of the way serialization works; a field serialized as a
> string will be displayed incorrectly if read as an integer.
> Unfortunately, as a side effect, this behavior limits the ability to add new
> columns to already exiting partitions using ALTER TABLE ADD COLUMNS. A
> possible workaround is to manually recreate the partitions, but this process
> could be unnecessarily cumbersome if the number of partitions is high. New
> columns should be propagated to existing partitions automatically instead.
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