org.objectweb.medor.eval.api
Interface NodeEvaluator
- BinaryIteratifNodeEvaluator, TupleCollectionNodeEvaluator, UnaryIteratifNodeEvaluator
public interface NodeEvaluator
This interface defines the controller object for the evaluation of a given
QueryNode within a QueryTree. It is created at evaluation time by the
NodeEvaluatorFactory, on request from the QueryEvaluator.
The QueryEvaluator controls the overall evaluation by activating/killing
the NodeEvaluator instances.
fetchData
public TupleCollection fetchData(ParameterOperand[] parameters)
throws MedorException
This method executes the query on the underlying node.
It controls the evaluation locally for this node.
It returns the TupleCollection containing the result of the execution.
getCacheSize
public long getCacheSize()
getEvaluationMetaData
public EvaluationMetaData getEvaluationMetaData()
Returns the evaluation meta data associated with this node evaluator.
- the associated EvaluationMetaData
getQueryNode
public QueryNode getQueryNode()
Returns the QueryNode to which the NodeEvaluator is attached.
linkChildren
public boolean linkChildren()
Opens the links between the current NodeEvaluator and the NodeEvaluators
of the children QueryTrees for pipelining operations.
TODO complete comments
setCacheSize
public void setCacheSize(long cacheSize)
setPrefetchBuffer
public void setPrefetchBuffer(PrefetchBuffer pb)
throws MedorException
Associates a PrefetchBuffer to be filled by the collection computed by
this evaluator.
pb
- The PrefetchBuffer to be filled.
unlinkChildren
public boolean unlinkChildren()
Closes the links between the current NodeEvaluator and the NodeEvaluators
of the children QueryTrees for pipelining operations.
TODO complete comments