de.fuberlin.wiwiss.ng4j.triql
Class QueryExecutionService

java.lang.Object
  de.fuberlin.wiwiss.ng4j.triql.QueryExecutionService

public class QueryExecutionService
extends Object

Executes a TriQL query and returns results. This class is used by TriQLQuery.getResults() and is usually not used explicitly.

The class implements the TriQL query algorithm. It's a na•ve implementation. The first triple pattern is matched against the proper graph(s), then for every match, a recursive call matches the second pattern, etc. Finally, the constraint clauses are evaluated. For this part, the RDQL implementation is used.

TODO: Refactor containsNonMatchingDuplicates(); it should check for duplicate variables in a single graph pattern before the query executes, and do the runtime checks only if any were found

Author:

Richard Cyganiak (richard@cyganiak.de)

Constructor Summary

QueryExecutionService(TriQLQuery query)
Constructs a new QueryExecutionService from a TriQL query.

Method Summary

List	execute() Executes the query and returns a list of results.

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryExecutionService

public QueryExecutionService(TriQLQuery query)

Constructs a new QueryExecutionService from a TriQL query.

Parameters:

query - a TriQL query object

Method Detail

execute

public List execute()

Executes the query and returns a list of results.

Returns:

a list of maps from variable names to result Nodes