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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/Design" by NamitJain
Date Thu, 26 Feb 2009 02:34:50 GMT
Dear Wiki user,

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The following page has been changed by NamitJain:
http://wiki.apache.org/hadoop/Hive/Design

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  == Optimizer ==
+ More plan transformations are performed	by the optimizer. The optimizer	is an evolving component.
Currently, it	is rule-based and performs the following: column pruning, and predicate pushdown.
However, the infrastructure is in place, and there is work under progress to include other
optimizations like map-side join. The optimizer can be enhanced to be cost-based. The sorted
nature of output tables can also be preserved and used later on to generate better plans.
The query can be
+ performed on a small sample of data to guess the data distribution, which can be used to
generate a better plan. The plan is a generic operator tree, and can be easily manipulated.
  
  == Execution ==
  

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