Skip to content

Commit

Permalink
GH-4646 remove intermediate joins
Browse files Browse the repository at this point in the history
  • Loading branch information
@JervenBolleman
JervenBolleman committed Jul 28, 2023
1 parent d4a4e0c commit 5c19780
Show file tree
Hide file tree
Showing 2 changed files with 47 additions and 31 deletions.
77 changes: 46 additions & 31 deletions ...tion/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/PathIteration.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
*******************************************************************************/
package org.eclipse.rdf4j.query.algebra.evaluation.iterator;

import java.util.HashSet;
import java.util.Queue;
import java.util.Set;

Expand Down Expand Up @@ -65,6 +66,8 @@ public class PathIteration extends LookAheadIteration<BindingSet, QueryEvaluatio
private ValuePair currentVp;

private static final String JOINVAR_PREFIX = "intermediate_join_";

private final Set<String> namedIntermediateJoins = new HashSet<>();

public PathIteration(EvaluationStrategy strategy, Scope scope, Var startVar,
TupleExpr pathExpression, Var endVar, Var contextVar, long minLength, BindingSet bindings)
Expand Down Expand Up @@ -104,10 +107,10 @@ protected BindingSet getNextElement() throws QueryEvaluationException {

while (currentIter != null && currentIter.hasNext()) {
BindingSet potentialNextElement = currentIter.next();
MutableBindingSet nextElement;
QueryBindingSet nextElement;
// if it is not a compatible type of BindingSet
if (potentialNextElement instanceof QueryBindingSet) {
nextElement = (MutableBindingSet) potentialNextElement;
nextElement = (QueryBindingSet) potentialNextElement;
} else {
nextElement = new QueryBindingSet(potentialNextElement);
}
Expand All @@ -121,22 +124,10 @@ protected BindingSet getNextElement() throws QueryEvaluationException {
}
}

Value v1, v2;
ValuePair vp = valuePairFromStartAndEnd(nextElement);

if (startVarFixed && endVarFixed && currentLength > 2) {
v1 = getVarValue(startVar, startVarFixed, nextElement);
v2 = nextElement.getValue("END_" + JOINVAR_PREFIX + this.hashCode());
} else if (startVarFixed && endVarFixed && currentLength == 2) {
v1 = getVarValue(startVar, startVarFixed, nextElement);
v2 = nextElement.getValue(JOINVAR_PREFIX + (currentLength - 1) + "_" + this.hashCode());
} else {
v1 = getVarValue(startVar, startVarFixed, nextElement);
v2 = getVarValue(endVar, endVarFixed, nextElement);
}

if (!isCyclicPath(v1, v2)) {
if (!isCyclicPath(vp)) {

ValuePair vp = new ValuePair(v1, v2);
if (reportedValues.contains(vp)) {
// new arbitrary-length path semantics: filter out
// duplicates
Expand All @@ -151,38 +142,38 @@ protected BindingSet getNextElement() throws QueryEvaluationException {

if (startVarFixed && endVarFixed) {
Value endValue = getVarValue(endVar, endVarFixed, nextElement);
if (endValue.equals(v2)) {
if (endValue.equals(vp.endValue)) {
add(reportedValues, vp);
if (!v1.equals(v2)) {
if (!vp.startValue.equals(vp.endValue)) {
addToQueue(valueQueue, vp);
}
if (!nextElement.hasBinding(startVar.getName())) {
addBinding(nextElement, startVar.getName(), v1);
addBinding(nextElement, startVar.getName(), vp.startValue);
}
if (!nextElement.hasBinding(endVar.getName())) {
addBinding(nextElement, endVar.getName(), v2);
addBinding(nextElement, endVar.getName(), vp.endValue);
}
return nextElement;
return removeIntermediateJoinVars(nextElement);
} else {
if (add(unreportedValues, vp)) {
if (!v1.equals(v2)) {
if (!vp.startValue.equals(vp.endValue)) {
addToQueue(valueQueue, vp);
}
}
continue again;
}
} else {
add(reportedValues, vp);
if (!v1.equals(v2)) {
if (!vp.startValue.equals(vp.endValue)) {
addToQueue(valueQueue, vp);
}
if (!nextElement.hasBinding(startVar.getName())) {
addBinding(nextElement, startVar.getName(), v1);
addBinding(nextElement, startVar.getName(), vp.startValue);
}
if (!nextElement.hasBinding(endVar.getName())) {
addBinding(nextElement, endVar.getName(), v2);
addBinding(nextElement, endVar.getName(), vp.endValue);
}
return nextElement;
return removeIntermediateJoinVars(nextElement);
}
} else {
continue again;
Expand All @@ -198,6 +189,27 @@ protected BindingSet getNextElement() throws QueryEvaluationException {
}
}

private BindingSet removeIntermediateJoinVars(QueryBindingSet nextElement) {
nextElement.removeAll(namedIntermediateJoins);
return nextElement;
}

private ValuePair valuePairFromStartAndEnd(MutableBindingSet nextElement) {
Value v1, v2;

if (startVarFixed && endVarFixed && currentLength > 2) {
v1 = getVarValue(startVar, startVarFixed, nextElement);
v2 = nextElement.getValue("END_" + JOINVAR_PREFIX + this.hashCode()) ;
} else if (startVarFixed && endVarFixed && currentLength == 2) {
v1 = getVarValue(startVar, startVarFixed, nextElement);
v2 = nextElement.getValue(JOINVAR_PREFIX + (currentLength - 1) + "_"+ this.hashCode());
} else {
v1 = getVarValue(startVar, startVarFixed, nextElement);
v2 = getVarValue(endVar, endVarFixed, nextElement);
}
return new ValuePair(v1, v2);
}

private void addBinding(MutableBindingSet bs, String name, Value value) {
bs.addBinding(name, value);
}
Expand Down Expand Up @@ -242,12 +254,12 @@ private Value getVarValue(Var var, boolean fixedValue, BindingSet bindingSet) {
return v;
}

private boolean isCyclicPath(Value v1, Value v2) {
private boolean isCyclicPath(ValuePair vp) {
if (currentLength <= 2) {
return false;
}

return reportedValues.contains(new ValuePair(v1, v2));
return reportedValues.contains(vp);

}

Expand Down Expand Up @@ -426,9 +438,12 @@ public void meet(Var var) {

}

private Var createAnonVar(String varName, Value v, boolean anonymous) {
namedIntermediateJoins.add(varName);
return new Var(varName, null, anonymous, false);
}

public Var createAnonVar(String varName) {
Var var = new Var(varName);
var.setAnonymous(true);
return var;
return createAnonVar(varName, null, true);
}
}
1 change: 1 addition & 0 deletions .../src/test/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/PathIterationTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -110,6 +110,7 @@ void assertExpected(BindingSet result, Value subClass, Value superClass) {
assertEquals(subClass, result.getBinding("subClass").getValue());
assertTrue(result.hasBinding("superClass"), "path zlp evaluation should binding for superClass var");
assertEquals(superClass, result.getBinding("superClass").getValue());
assertEquals(2, result.size());
}

@Test
Expand Down

0 comments on commit 5c19780

Please sign in to comment.