org.apache.pig.impl.logicalLayer.optimizer
Class PartitionFilterOptimizer
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.PartitionFilterOptimizer
public class PartitionFilterOptimizer
- extends LogicalTransformer
When the load statement in a pig script is loading a table from a meta data
system (like owl), the load can be followed by a filter which can contain
conditions on partition columns. This filter can also contain conditions on
non partition columns. This optimizer looks at the logical plan and checks if
there is a load followed by such a filter which has conditions on partition
columns. If so, it extracts the conditions on partition columns out of the
filter.
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 |
PartitionFilterOptimizer
protected PartitionFilterOptimizer(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
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