org.eclipse.rdf4j.query.algebra.evaluation.impl

Class QueryJoinOptimizer.JoinVisitor

java.lang.Object

org.eclipse.rdf4j.query.algebra.helpers.AbstractQueryModelVisitor<RuntimeException>

org.eclipse.rdf4j.query.algebra.evaluation.impl.QueryJoinOptimizer.JoinVisitor

All Implemented Interfaces:

QueryModelVisitor<RuntimeException>

Enclosing class:

QueryJoinOptimizer

protected class QueryJoinOptimizer.JoinVisitor
extends AbstractQueryModelVisitor<RuntimeException>

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	JoinVisitor()

Method Summary

Modifier and Type	Method and Description
protected List<Var>	getConstantVars(Iterable<Var> vars)
protected List<Extension>	getExtensions(List<TupleExpr> expressions)
protected int	getForeignVarFreq(List<Var> ownUnboundVars, Map<Var,Integer> varFreqMap)
protected <L extends List<TupleExpr>> L	getJoinArgs(TupleExpr tupleExpr, L joinArgs)
protected List<Var>	getStatementPatternVars(TupleExpr tupleExpr)
protected List<TupleExpr>	getSubSelects(List<TupleExpr> expressions)
protected double	getTupleExprCardinality(TupleExpr tupleExpr, Map<TupleExpr,Double> cardinalityMap, Map<TupleExpr,List<Var>> varsMap, Map<Var,Integer> varFreqMap, Set<String> boundVars)
protected List<Var>	getUnboundVars(Iterable<Var> vars)
protected <M extends Map<Var,Integer>> M	getVarFreqMap(List<Var> varList, M varFreqMap)
void	meet(Join node)
void	meet(LeftJoin leftJoin)
protected List<TupleExpr>	reorderSubselects(List<TupleExpr> subselects) Determines an optimal ordering of subselect join arguments, based on variable bindings.
protected TupleExpr	selectNextTupleExpr(List<TupleExpr> expressions, Map<TupleExpr,Double> cardinalityMap, Map<TupleExpr,List<Var>> varsMap, Map<Var,Integer> varFreqMap, Set<String> boundVars) Selects from a list of tuple expressions the next tuple expression that should be evaluated.

Methods inherited from class org.eclipse.rdf4j.query.algebra.helpers.AbstractQueryModelVisitor

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, meetNode, meetOther, meetSubQueryValueOperator, meetUnaryTupleOperator, meetUnaryValueOperator, meetUpdateExpr

Methods inherited from class java.lang.Object

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

Constructor Detail

JoinVisitor

protected JoinVisitor()

Method Detail

meet

public void meet(LeftJoin leftJoin)

Specified by:

meet in interface QueryModelVisitor<RuntimeException>

Overrides:

meet in class AbstractQueryModelVisitor<RuntimeException>

meet

public void meet(Join node)

Specified by:

meet in interface QueryModelVisitor<RuntimeException>

Overrides:

meet in class AbstractQueryModelVisitor<RuntimeException>

getJoinArgs

protected <L extends List<TupleExpr>> L getJoinArgs(TupleExpr tupleExpr,
                                                    L joinArgs)

getStatementPatternVars

protected List<Var> getStatementPatternVars(TupleExpr tupleExpr)

getVarFreqMap

protected <M extends Map<Var,Integer>> M getVarFreqMap(List<Var> varList,
                                                       M varFreqMap)

getExtensions

protected List<Extension> getExtensions(List<TupleExpr> expressions)

getSubSelects

protected List<TupleExpr> getSubSelects(List<TupleExpr> expressions)

reorderSubselects

protected List<TupleExpr> reorderSubselects(List<TupleExpr> subselects)

Determines an optimal ordering of subselect join arguments, based on variable bindings. An ordering is considered optimal if for each consecutive element it holds that first of all its shared variables with all previous elements is maximized, and second, the union of all its variables with all previous elements is maximized.

Example: reordering

   [f] [a b c] [e f] [a d] [b e]
 

should result in:

   [a b c] [a d] [b e] [e f] [f]
 

Parameters:

subselects - the original ordering of expressions

Returns:

the optimized ordering of expressions

selectNextTupleExpr

protected TupleExpr selectNextTupleExpr(List<TupleExpr> expressions,
                                        Map<TupleExpr,Double> cardinalityMap,
                                        Map<TupleExpr,List<Var>> varsMap,
                                        Map<Var,Integer> varFreqMap,
                                        Set<String> boundVars)

Selects from a list of tuple expressions the next tuple expression that should be evaluated. This method selects the tuple expression with highest number of bound variables, preferring variables that have been bound in other tuple expressions over variables with a fixed value.

getTupleExprCardinality

protected double getTupleExprCardinality(TupleExpr tupleExpr,
                                         Map<TupleExpr,Double> cardinalityMap,
                                         Map<TupleExpr,List<Var>> varsMap,
                                         Map<Var,Integer> varFreqMap,
                                         Set<String> boundVars)

getConstantVars

protected List<Var> getConstantVars(Iterable<Var> vars)

getUnboundVars

protected List<Var> getUnboundVars(Iterable<Var> vars)

getForeignVarFreq

protected int getForeignVarFreq(List<Var> ownUnboundVars,
                                Map<Var,Integer> varFreqMap)