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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/Locking" by NamitJain
Date Wed, 05 May 2010 05:23:38 GMT
Dear Wiki user,

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

The "Hive/Locking" page has been changed by NamitJain.
http://wiki.apache.org/hadoop/Hive/Locking?action=diff&rev1=12&rev2=13

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

  In order to avoid deadlocks, a very simple scheme is proposed here. All	the objects to be
locked
  are sorted lexicographically, and the required mode lock is acquired. Note that	in some
cases, the
  list of objects may not be known - for eg. in case of dynamic partitions, the list of partitions
- being modified is not known at compile time - so, the list is generated conservatively.
+ being modified is not known at compile time - so, the list is generated conservatively.
Since the 
+ number of partitions may not be known, an exclusive lock is taken on the table, or the prefix
that 
+ is known. 
  
  Two new configurable parameters will be added to decide the number of retries for the lock
and the 
  wait time between each retry. If the number of retries are really high, it can lead to a
live lock.

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