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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/ViewDev" by JohnSichi
Date Thu, 28 Jan 2010 23:49:19 GMT
Dear Wiki user,

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

The "Hive/ViewDev" page has been changed by JohnSichi.
http://wiki.apache.org/hadoop/Hive/ViewDev?action=diff&rev1=13&rev2=14

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

  
  After the tables are altered, the new columns will contain NULL values for existing rows
describing previously created tables.  This is correct for VIEW_ORIGINAL_TEXT and VIEW_EXPANDED_TEXT
(since views did not previously exist), but is incorrect for the TBL_TYPE column introduced
by [[https://issues.apache.org/jira/browse/HIVE-1068|HIVE-1068]].  The new Hive code is capable
of handling this (automatically filling in the correct value for the new field when a descriptor
is retrieved), but it does not "fix" the stored rows.  This could be an issue if in the future
other tools are used to retrieve information directly from the metastore database rather than
accessing the metastore API.
  
- The script below can be used to fix existing rows after the tables have been altered.  It
should be run in the specified order, and AFTER all Hive instances directly accessing the
metastore database have been upgraded.  For safety, it is view-aware just in case a CREATE
VIEW statement has already been executed, meaning it can be rerun any time after the upgrade.
+ The script below can be used to fix existing rows after the tables have been altered.  It
should be run AFTER all Hive instances directly accessing the metastore database have been
upgraded (otherwise new null values could slip in and remain forever).  For safety, it is
view-aware just in case a CREATE VIEW statement has already been executed, meaning it can
be rerun any time after the upgrade.
  
  {{{
  UPDATE TBLS SET TBL_TYPE='MANAGED_TABLE'

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