org.apache.pig.newplan.logical.rules

Class LimitOptimizer.OptimizeLimitTransformer

java.lang.Object

org.apache.pig.newplan.optimizer.Transformer

org.apache.pig.newplan.logical.rules.LimitOptimizer.OptimizeLimitTransformer

Enclosing class:

LimitOptimizer

public class LimitOptimizer.OptimizeLimitTransformer
extends Transformer

Constructor Summary

Constructors

Constructor and Description
OptimizeLimitTransformer()

Method Summary

Modifier and Type	Method and Description
boolean	check(OperatorPlan matched) check if the transform should be done.
OperatorPlan	reportChanges() Report what parts of the tree were transformed.
void	transform(OperatorPlan matched) Transform the tree

Methods inherited from class java.lang.Object

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

Constructor Detail

OptimizeLimitTransformer

public OptimizeLimitTransformer()

Method Detail

check

public boolean check(OperatorPlan matched)

Description copied from class: Transformer

check if the transform should be done. If this is being called then the pattern matches, but there may be other criteria that must be met as well.

Specified by:

check in class Transformer

Parameters:

matched - the sub-set of the plan that matches the pattern. This subset has the same graph as the pattern, but the operators point to the same objects as the plan to be matched.

Returns:

true if the transform should be done.

reportChanges

public OperatorPlan reportChanges()

Description copied from class: Transformer

Report what parts of the tree were transformed. This is so that listeners can know which part of the tree to visit and modify schemas, annotations, etc. So any nodes that were removed need will not be in this plan, only nodes that were added or moved.

Specified by:

reportChanges in class Transformer

Returns:

OperatorPlan that describes just the changed nodes.

transform

public void transform(OperatorPlan matched)
               throws FrontendException

Description copied from class: Transformer

Transform the tree

Specified by:

transform in class Transformer

Parameters:

matched - the sub-set of the plan that matches the pattern. This subset has the same graph as the pattern, but the operators point to the same objects as the plan to be matched.

Throws:

FrontendException