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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/PartitionedViews" by JohnSichi
Date Wed, 09 Feb 2011 23:28:09 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "Hive/PartitionedViews" page has been changed by JohnSichi.
http://wiki.apache.org/hadoop/Hive/PartitionedViews?action=diff&rev1=11&rev2=12

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  = Use Cases =
  
-  1. An administrator wants to create a set of views as a table/column renaming layer on
top of an existing set of base tables, without disturbing the ETL processes which load those
tables.  To read-only users, the views should behave exactly the same as the underlying tables
in every way.  Among other things, this means users should be able to browse available partitions.
+  1. An administrator wants to create a set of views as a table/column renaming layer on
top of an existing set of base tables, without breaking any existing dependencies on those
tables.  To read-only users, the views should behave exactly the same as the underlying tables
in every way.  Among other things, this means users should be able to browse available partitions.
   1. A base table is partitioned on columns (ds,hr) for date and hour.  Besides this fine-grained
partitioning, users would also like to see a virtual table of coarse-grained (date-only) partitioning
in which the partition for a given date only appears after all of the hour-level partitions
of that day have been fully loaded.
   1. A view is defined on a complex join+union+aggregation of a number of underlying base
tables and other views, all of which are themselves partitioned.  The top-level view should
also be partitioned accordingly, with a new partition not appearing until corresponding partitions
have been loaded for all of the underlying tables.
  

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