[jira] [Created] (HIVE-5095) Hive needs new operator walker for parallelization/optimization.

["Vikram Dixit K (JIRA)" <ji...@apache.org>]

Vikram Dixit K created HIVE-5095:
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             Summary: Hive needs new operator walker for parallelization/optimization.
                 Key: HIVE-5095
                 URL: https://issues.apache.org/jira/browse/HIVE-5095
             Project: Hive
          Issue Type: Bug
          Components: Tez
    Affects Versions: tez-branch
            Reporter: Vikram Dixit K
            Assignee: Vikram Dixit K
             Fix For: tez-branch


For tez to compute the number of reducers, we should be walking the operator tree in a topological fashion so that the reducers down the tree get the estimate from all parents. However, the current walkers in hive only walk the operator tree in a depth-first fashion. We need to add a new walker for the topological walk. Also, since information about the parent operators needs to be propagated on a per parent basis, we need to retain some context across operators to be passed to the child which the walker will co-ordinate.

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