org.objectweb.medor.eval.lib
Class MedorEvaluator

java.lang.Object
  org.objectweb.medor.eval.lib.MedorEvaluator

All Implemented Interfaces:

QueryEvaluator

public class MedorEvaluator

extends java.lang.Object

implements QueryEvaluator

This class is a simple evaluator of query tree, supporting the data prefetching

Author:

S.Chassande-Barrioz

Constructor Summary

MedorEvaluator(QueryTree query, long cacheSize)

Method Summary

TupleCollection	evaluate(ParameterOperand[] parameters, ConnectionResources resources, java.util.Map evaluationMDMap) First, it allocates a tree of Evaluator (Wrapper or NodeEvaluator) for the query tree associated to this evaluator.
TupleCollection	evaluate(ParameterOperand[] parameters, ConnectionResources resources, PrefetchBuffer prefetchBuffer, java.util.Map evalMDMap) Launch the evaluation of a query.
long	getCacheSize()
QueryTree	getQueryTree()
ConnectionResources	getRequiredConnectionResources()
WrapperFactory	getWrapperFactory() Returns the associated WrapperFactory.

Methods inherited from class java.lang.Object

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

Constructor Detail

MedorEvaluator

public MedorEvaluator(QueryTree query,
                      long cacheSize)
               throws EvaluationException

Method Detail

getWrapperFactory

public WrapperFactory getWrapperFactory()

Description copied from interface: QueryEvaluator

Returns the associated WrapperFactory. This is used to be able to bind specific Wrappers to DataStore types.

Specified by:

getWrapperFactory in interface QueryEvaluator

Returns:

the associated WrapperFactory

evaluate

public TupleCollection evaluate(ParameterOperand[] parameters,
                                ConnectionResources resources,
                                java.util.Map evaluationMDMap)
                         throws EvaluationException

First, it allocates a tree of Evaluator (Wrapper or NodeEvaluator) for the query tree associated to this evaluator. In a second step it launches the evalution of the query.

Specified by:

evaluate in interface QueryEvaluator

Parameters:

parameters - is the array of parameters

resources - is the holder of connection used by the wrapper to access the data support.

evaluationMDMap - contains a map associating an EvaluationMetaData object to each of the query nodes of the query tree currently associated to the QueryEvaluator.

Throws:

EvaluationException

evaluate

public TupleCollection evaluate(ParameterOperand[] parameters,
                                ConnectionResources resources,
                                PrefetchBuffer prefetchBuffer,
                                java.util.Map evalMDMap)
                         throws EvaluationException

Description copied from interface: QueryEvaluator

Launch the evaluation of a query. This method is able to prefetch data of the query in a prefetch buffer.

Specified by:

evaluate in interface QueryEvaluator

Parameters:

parameters - is a ConnectionResources containing associations between the DataStore names used in the QueryTree and the connection objects to use for the evaluation.

prefetchBuffer - is the prefetchBuffer instance where buffer data must be put. If this field is null, then no data prefetching mus be done.

resources - is a ConnectionResources containing associations between the DataStore names used in the QueryTree and the connection objects to use for the evaluation.It can be null.

Throws:

EvaluationException

getQueryTree

public QueryTree getQueryTree()

Specified by:

getQueryTree in interface QueryEvaluator

Returns:

the evaluable (optimized) query tree associated to the current QueryEvaluator.

getCacheSize

public long getCacheSize()

Specified by:

getCacheSize in interface QueryEvaluator

Returns:

the cache size used in different node of the QueryNode tree.

getRequiredConnectionResources

public ConnectionResources getRequiredConnectionResources()

Specified by:

getRequiredConnectionResources in interface QueryEvaluator