Class TripleRefJoinOptimizer

java.lang.Object

org.eclipse.rdf4j.query.algebra.helpers.AbstractSimpleQueryModelVisitor<OptimizationException>

org.eclipse.rdf4j.federated.optimizer.TripleRefJoinOptimizer

All Implemented Interfaces:

FedXOptimizer, QueryModelVisitor<OptimizationException>

public class TripleRefJoinOptimizer
extends AbstractSimpleQueryModelVisitor<OptimizationException>
implements FedXOptimizer

Optimizer that groups TripleRefStatementPattern nodes with co-located StatementPattern nodes into TripleRefJoinGroup instances, enabling efficient federated evaluation of RDF 1.2 reification patterns.

The optimizer visits every NJoin in the query tree (depth-first) and looks for pairs of a TripleRefStatementPattern and one or more plain StatementPatterns that share the same unbound subject variable. Matched patterns are collapsed into a single TripleRefJoinGroup that can be sent as one request to the owning endpoints.

Author:

Andreas Schwarte

See Also:

• TripleRefJoinGroup
• TripleRefStatementPattern

Field Summary

Fields

Modifier and Type	Field	Description
protected final QueryInfo	queryInfo

Constructor Summary

Constructors

Constructor	Description
TripleRefJoinOptimizer(QueryInfo queryInfo)

Method Summary

Modifier and Type	Method	Description
protected List<TupleExpr>	formGroups(List<TupleExpr> originalArgs)	Group TripleRefStatementPattern and StatementPattern having the same subject variable into a TripleRefJoinGroup.
void	meet(Service tupleExpr)
protected void	meetNJoin(NJoin node)
void	meetOther(QueryModelNode node)
void	optimize(TupleExpr tupleExpr)	Optimize the provided tuple expression

Methods inherited from class AbstractSimpleQueryModelVisitor

meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meet, meetBinaryTupleOperator, meetBinaryValueOperator, meetCompareSubQueryValueOperator, meetNAryValueOperator, meetSubQueryValueOperator, meetUnaryTupleOperator, meetUnaryValueOperator, meetUnsupported, meetUpdateExpr

Methods inherited from class Object

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

Field Details

queryInfo

protected final QueryInfo queryInfo

Constructor Details

TripleRefJoinOptimizer

public TripleRefJoinOptimizer(QueryInfo queryInfo)

Method Details

optimize

public void optimize(TupleExpr tupleExpr)

Description copied from interface: FedXOptimizer

Optimize the provided tuple expression

Specified by:

optimize in interface FedXOptimizer

Parameters:

tupleExpr -

meet

public void meet(Service tupleExpr)

Specified by:

meet in interface QueryModelVisitor<OptimizationException>

Overrides:

meet in class AbstractSimpleQueryModelVisitor<OptimizationException>

meetOther

public void meetOther(QueryModelNode node)

Specified by:

meetOther in interface QueryModelVisitor<OptimizationException>

Overrides:

meetOther in class AbstractSimpleQueryModelVisitor<OptimizationException>

meetNJoin

protected void meetNJoin(NJoin node)

formGroups

protected List<TupleExpr> formGroups(List<TupleExpr> originalArgs)

Group TripleRefStatementPattern and StatementPattern having the same subject variable into a TripleRefJoinGroup.

Assumption: a shared unbound subject variable is treated as a sufficient co-location signal. In RDF 1.2 reification patterns the subject linking the outer statement to its triple term is typically a blank node that is local to a single dataset (and therefore to a single endpoint). No additional source-exclusivity check is performed.

Parameters:

originalArgs - the join arguments to group

Returns:

the new (potentially grouped) join arguments. If empty, the join will not produce any results.