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From Paul Yang <py...@facebook.com>
Subject RE: Schema evolution?
Date Thu, 01 Jul 2010 23:56:53 GMT
There exists structures for supporting this in the metastore, but that feature isn't in Hive
yet. For example, although the metadata for partitions include its own set of columns, parts
of the code in the query processor still read from table level metadata.

Some evolution can occur in the form of adding columns to a table.

-----Original Message-----
From: Yang [mailto:teddyyyy123@gmail.com] 
Sent: Thursday, July 01, 2010 4:43 PM
To: hive-user@hadoop.apache.org
Subject: Schema evolution?

I read on the VLBD hive paper "Hive - A Warehousing Solution Over a
Map-Reduce    Framework"
that Partitions could have different schemas : (section 3.1 MetaStore) "
Partition - Each partition can have its own columns
and SerDe and storage information. This can be used
in the future to support schema evolution in a Hive
warehouse.
"

but the API:
http://hadoop.apache.org/hive/docs/r0.5.0/api/

only lists getSchema() for Table, and Partition does not have a
separate getSchema().

is the schema evolution feature really there?

Thanks
Yang

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