org.apache.pig.backend.hadoop.executionengine.mapReduceLayer
Class SampleOptimizer

java.lang.Object
  org.apache.pig.impl.plan.PlanVisitor<MapReduceOper,MROperPlan>
      org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.plans.MROpPlanVisitor
          org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.SampleOptimizer

public class SampleOptimizer
extends MROpPlanVisitor

A visitor to optimize plans that have a sample job that immediately follows a load/store only MR job. These kinds of plans are generated for order bys, and will soon be generated for joins that need to sample their data first. These can be changed so that the RandomSampleLoader subsumes the loader used in the first job and then removes the first job.

Field Summary

Fields inherited from class org.apache.pig.impl.plan.PlanVisitor

mCurrentWalker, mPlan

Constructor Summary

SampleOptimizer(MROperPlan plan, PigContext pigContext)

Method Summary

void	visit() Entry point for visiting the plan.
void	visitMROp(MapReduceOper mr)

Methods inherited from class org.apache.pig.impl.plan.PlanVisitor

getPlan, popWalker, pushWalker

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SampleOptimizer

public SampleOptimizer(MROperPlan plan,
                       PigContext pigContext)

Method Detail

visit

public void visit()
           throws VisitorException

Description copied from class: PlanVisitor

Entry point for visiting the plan.

Overrides:

visit in class PlanVisitor<MapReduceOper,MROperPlan>

Throws:

VisitorException - if an error is encountered while visiting.

visitMROp

public void visitMROp(MapReduceOper mr)
               throws VisitorException

Overrides:

visitMROp in class MROpPlanVisitor

Throws:

VisitorException