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

java.lang.Object
  org.apache.pig.newplan.logical.rules.ColumnPruneHelper

public class ColumnPruneHelper
extends Object

Helper class used by ColumnMapKeyPrune to figure out what columns can be pruned. It doesn't make any changes to the operator plan

Field Summary

protected static String	INPUTUIDS
static String	OUTPUTUIDS
protected static String	REQUIREDCOLS

Constructor Summary

ColumnPruneHelper(OperatorPlan currentPlan)

Method Summary

boolean	check()
protected Set<Integer>	getColumns(LogicalSchema schema, Set<Long> uids)
OperatorPlan	reportChanges()

Methods inherited from class java.lang.Object

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

Field Detail

INPUTUIDS

protected static final String INPUTUIDS

See Also:

Constant Field Values

OUTPUTUIDS

public static final String OUTPUTUIDS

See Also:

Constant Field Values

REQUIREDCOLS

protected static final String REQUIREDCOLS

See Also:

Constant Field Values

Constructor Detail

ColumnPruneHelper

public ColumnPruneHelper(OperatorPlan currentPlan)

Method Detail

check

public boolean check()
              throws FrontendException

Throws:

FrontendException

getColumns

protected Set<Integer> getColumns(LogicalSchema schema,
                                  Set<Long> uids)
                           throws FrontendException

Throws:

FrontendException

reportChanges

public OperatorPlan reportChanges()