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From "Mariano Dominguez (JIRA)" <>
Subject [jira] [Created] (HIVE-7046) Propagate addition of new columns to partition schema
Date Mon, 12 May 2014 15:47:24 GMT
Mariano Dominguez created HIVE-7046:

             Summary: Propagate addition of new columns to partition schema
                 Key: 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 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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