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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/PartitionedViews" by JohnSichi
Date Wed, 09 Feb 2011 22:52:24 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=10&rev2=11

--------------------------------------------------

  
  Currently, changing a view definition requires dropping the view and recreating it.  This
implies dropping and recreating all existing partitions as well, which could be very expensive.
  
- This implies that followup support for [[https://issues.apache.org/jira/browse/HIVE-1078|CREATE
OR REPLACE]] is very important, and that it needs to preserve existing partitions (after validating
that they are still compatible with the new view definition).
+ This implies that followup support for [[https://issues.apache.org/jira/browse/HIVE-1078|CREATE
OR REPLACE VIEW]] is very important, and that it needs to preserve existing partitions (after
validating that they are still compatible with the new view definition).
  
+ = Hook Information =
+ 
+ Although there is currently no connection between the view partition and underlying table
partitions, Hive does provide dependency information as part of the hook invocation for ALTER
VIEW ADD PARTITION.  It does this by compiling an internal query of the form
+ 
+ {{{
+ SELECT * FROM view_name
+ WHERE view_partition_col1 = 'val1' AND view_partition_col=2 = 'val2' ...
+ }}}
+ 
+ and then capturing the table/partition inputs for this query and passing them on to the
ALTER VIEW ADD PARTITION hook results.
+ 
+ This allows applications to track the dependencies themselves.  In the future, Hive will
automatically populate these depenencies into the metastore as part of [[https://issues.apache.org/jira/browse/HIVE-1073|HIVE-1073]].
+ 

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