org.apache.pig.newplan.logical.rules
Class ColumnMapKeyPrune

java.lang.Object
  extended by org.apache.pig.newplan.optimizer.Rule
      extended by org.apache.pig.newplan.logical.rules.WholePlanRule
          extended by org.apache.pig.newplan.logical.rules.ColumnMapKeyPrune

public class ColumnMapKeyPrune
extends WholePlanRule

This Rule prunes columns and map keys and set to loader. This rule depends on MapKeysPruneHelper to calculate what keys are required for a loader, and ColumnPruneHelper to calculate the required columns for a loader. Then it combines the map keys and columns info to set into the loader.


Nested Class Summary
 class ColumnMapKeyPrune.ColumnMapKeyPruneTransformer
           
 
Field Summary
 
Fields inherited from class org.apache.pig.newplan.optimizer.Rule
currentPlan, log, name, pattern
 
Constructor Summary
ColumnMapKeyPrune(String n)
           
 
Method Summary
 Transformer getNewTransformer()
          Get the transformer for this rule.
 
Methods inherited from class org.apache.pig.newplan.logical.rules.WholePlanRule
buildPattern, match
 
Methods inherited from class org.apache.pig.newplan.optimizer.Rule
getName, getPattern, isMandatory, isSkipListener, setSkipListener
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ColumnMapKeyPrune

public ColumnMapKeyPrune(String n)
Method Detail

getNewTransformer

public Transformer getNewTransformer()
Description copied from class: Rule
Get the transformer for this rule. Abstract because the rule may want to choose how to instantiate the transformer. This should never return a cached transformer, it should always return a fresh one with no state.

Specified by:
getNewTransformer in class Rule
Returns:
Transformer to use with this rule


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