org.apache.pig.impl.logicalLayer.optimizer
Class PushDownForeachFlatten
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.PushDownForeachFlatten
public class PushDownForeachFlatten
- extends LogicalTransformer
A visitor to discover if a foreach with flatten(s) can be pushed as low down the tree as
possible.
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 |
PushDownForeachFlatten
public PushDownForeachFlatten(LogicalPlan plan)
getSwap
public boolean getSwap()
- Returns:
- true if the foreach has to swapped; false otherwise
getInsertBetween
public boolean getInsertBetween()
- Returns:
- true if the foreach has to be inserted after its successor; false
otherwise
getFlattenedColumnMap
public Map<Integer,Integer> getFlattenedColumnMap()
- Returns:
- a map of old column position in the foreach to the column
position in foreach's successor
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
reset
public void reset()
- Description copied from class:
Transformer
- Reset any internal state after the transformation.
- Overrides:
reset
in class LogicalTransformer
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