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

java.lang.Object
  org.apache.pig.newplan.optimizer.Rule
      org.apache.pig.newplan.logical.rules.GroupByConstParallelSetter

public class GroupByConstParallelSetter
extends Rule

Rule: If a LOCogroup is 'group all', set the parallelism to 1, or in general - if the group-by expression is just a constant then set parallelism to 1 LogicalExpressionSimplifier could be used to convert an expression with constants into a single ConstantExpression

Nested Class Summary

class

GroupByConstParallelSetter.GroupAllParallelSetterTransformer

Field Summary

Fields inherited from class org.apache.pig.newplan.optimizer.Rule

currentPlan, name, pattern

Constructor Summary

GroupByConstParallelSetter(String n)

Method Summary

protected OperatorPlan	buildPattern() Build the pattern that this rule will look for
Transformer	getNewTransformer() Get the transformer for this rule.

Methods inherited from class org.apache.pig.newplan.optimizer.Rule

getName, getPattern, isMandatory, isSkipListener, match, setSkipListener

Methods inherited from class java.lang.Object

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

Constructor Detail

GroupByConstParallelSetter

public GroupByConstParallelSetter(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

buildPattern

protected OperatorPlan buildPattern()

Description copied from class: Rule

Build the pattern that this rule will look for

Specified by:

buildPattern in class Rule

Returns:

the pattern to look for by this rule