org.apache.pig.impl.logicalLayer.optimizer
Class PruneColumns
java.lang.Object
org.apache.pig.impl.plan.optimizer.Transformer<LogicalOperator,LogicalPlan>
org.apache.pig.impl.logicalLayer.optimizer.LogicalTransformer
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns
public class PruneColumns
- extends LogicalTransformer
Fields inherited from class org.apache.pig.impl.plan.optimizer.Transformer |
mPlan |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
PruneColumns
public PruneColumns(LogicalPlan plan)
check
public boolean check(List<LogicalOperator> nodes)
throws OptimizerException
- 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<LogicalOperator,LogicalPlan>
- Parameters:
nodes
- - List of nodes declared in transform ($1 = nodes[0],
etc.) Remember that somes entries in node[] may be NULL since they may
not be created until after the transform.
- Returns:
- true if the transform should be done.
- Throws:
OptimizerException
transform
public void transform(List<LogicalOperator> nodes)
throws OptimizerException
- Description copied from class:
Transformer
- Transform the tree
- Specified by:
transform
in class Transformer<LogicalOperator,LogicalPlan>
- Parameters:
nodes
- - List of nodes declared in transform ($1 = nodes[0],
etc.) This call must destruct any nodes that are being removed as part
of the transform and remove them from the nodes vector and construct
any that are being created as part of the transform and add them at the
appropriate point to the nodes vector.
- Throws:
OptimizerException
processNode
public void processNode(LogicalOperator lo,
org.apache.pig.impl.logicalLayer.optimizer.RequiredInfo requiredOutputInfo)
throws OptimizerException
- Throws:
OptimizerException
prune
public void prune()
throws OptimizerException
- Throws:
OptimizerException
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