org.apache.pig.backend.hadoop.executionengine.fetch
Class FetchOptimizer

java.lang.Object
  org.apache.pig.backend.hadoop.executionengine.fetch.FetchOptimizer

public class FetchOptimizer
extends Object

FetchOptimizer determines whether the entire physical plan is fetchable, meaning that the task's result can be directly read (fetched) from the underlying storage rather than creating MR jobs. During the check FetchablePlanVisitor is used to walk through the plan.

Constructor Summary

FetchOptimizer()

Method Summary

static boolean	isFetchEnabled(PigContext pc) Checks whether the fetch is enabled
static boolean	isPlanFetchable(PigContext pc, PhysicalPlan pp) Visits the plan with FetchablePlanVisitor and checks whether the plan is fetchable.

Methods inherited from class java.lang.Object

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

Constructor Detail

FetchOptimizer

public FetchOptimizer()

Method Detail

isFetchEnabled

public static boolean isFetchEnabled(PigContext pc)

Checks whether the fetch is enabled

Parameters:

pc -

Returns:

true if fetching is enabled

isPlanFetchable

public static boolean isPlanFetchable(PigContext pc,
                                      PhysicalPlan pp)
                               throws VisitorException

Visits the plan with FetchablePlanVisitor and checks whether the plan is fetchable.

Parameters:

pc - PigContext

pp - the physical plan to be examined

Returns:

true if the plan is fetchable

Throws:

VisitorException