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[Bigdata-commit] SF.net SVN: bigdata:[4376] branches/QUADS_QUERY_BRANCH/bigdata
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From: <mrp...@us...> - 2011-04-06 21:28:36
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Revision: 4376
http://bigdata.svn.sourceforge.net/bigdata/?rev=4376&view=rev
Author: mrpersonick
Date: 2011-04-06 21:28:29 +0000 (Wed, 06 Apr 2011)
Log Message:
-----------
added support for using hash joins for optional join groups
Modified Paths:
--------------
branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/bop/controller/SubqueryHashJoinOp.java
branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOp2BOpUtility.java
branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOpTree.java
branches/QUADS_QUERY_BRANCH/bigdata-sails/src/test/com/bigdata/rdf/sail/TestBOps.java
Modified: branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/bop/controller/SubqueryHashJoinOp.java
===================================================================
--- branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/bop/controller/SubqueryHashJoinOp.java 2011-04-06 21:27:45 UTC (rev 4375)
+++ branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/bop/controller/SubqueryHashJoinOp.java 2011-04-06 21:28:29 UTC (rev 4376)
@@ -508,6 +508,11 @@
final UnsyncLocalOutputBuffer<IBindingSet> unsyncBuffer = new UnsyncLocalOutputBuffer<IBindingSet>(
joinOp.getChunkCapacity(), sink);
+ // Thread-local buffer iff optional sink is in use.
+ final AbstractUnsynchronizedArrayBuffer<IBindingSet> unsyncBuffer2 = sink2 == null ? null
+ : new UnsyncLocalOutputBuffer<IBindingSet>(
+ joinOp.getChunkCapacity(), sink2);
+
// The iterator draining the subquery
final IAsynchronousIterator<IBindingSet[]> subquerySolutionItr = runningSubquery
.iterator();
@@ -554,7 +559,7 @@
* solutions produced by the join are rejected
* by the filter.
*/
- src.nhits++;
+// src.nhits++;
if (log.isDebugEnabled())
log.debug("Join with " + src);
@@ -582,11 +587,13 @@
if (log.isDebugEnabled())
log.debug("Join fails constraint(s): "
+ bset);
-
+
continue;
}
+ src.nhits++;
+
// strip off unnecessary variables.
bset = selectVars == null ? bset : bset
.copy(selectVars);
@@ -616,11 +623,6 @@
* any constraint on the join.
*/
- // Thread-local buffer iff optional sink is in use.
- final AbstractUnsynchronizedArrayBuffer<IBindingSet> unsyncBuffer2 = sink2 == null ? null
- : new UnsyncLocalOutputBuffer<IBindingSet>(
- joinOp.getChunkCapacity(), sink2);
-
for(Bucket b : map.values()) {
for(SolutionHit hit : b.solutions) {
@@ -633,21 +635,21 @@
if (log.isDebugEnabled())
log.debug("Optional solution: " + bs);
- if (constraints != null) {
- if (!BOpUtility.isConsistent(constraints,
- bs)) {
+// if (constraints != null) {
+// if (!BOpUtility.isConsistent(constraints,
+// bs)) {
+//
+// // Failed by the constraint on the join.
+//
+// if (log.isDebugEnabled())
+// log
+// .debug("Optional solution failed by constraints: "
+// + hit);
+//
+// continue;
+// }
+// }
- // Failed by the constraint on the join.
-
- if (log.isDebugEnabled())
- log
- .debug("Optional solution failed by constraints: "
- + hit);
-
- continue;
- }
- }
-
if (log.isTraceEnabled())
log.trace("Output optional solution: " + bs);
Modified: branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOp2BOpUtility.java
===================================================================
--- branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOp2BOpUtility.java 2011-04-06 21:27:45 UTC (rev 4375)
+++ branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOp2BOpUtility.java 2011-04-06 21:28:29 UTC (rev 4376)
@@ -62,6 +62,7 @@
import com.bigdata.bop.joinGraph.PartitionedJoinGroup;
import com.bigdata.bop.solutions.SliceOp;
import com.bigdata.rdf.sail.FreeTextSearchExpander;
+import com.bigdata.rdf.sail.QueryHints;
import com.bigdata.rdf.sail.Rule2BOpUtility;
import com.bigdata.rdf.sail.sop.SOpTree.SOpGroup;
import com.bigdata.rdf.sail.sop.SOpTree.SOpGroups;
@@ -262,17 +263,44 @@
idFactory,
queryHints);
} else {
- final PipelineOp subquery = convert(
- child, idFactory, db, queryEngine, queryHints);
- final boolean optional = isOptional(child);
- final int subqueryId = idFactory.incrementAndGet();
- left = new SubqueryOp(new BOp[]{left},
- new NV(Predicate.Annotations.BOP_ID, subqueryId),//
- new NV(SubqueryOp.Annotations.SUBQUERY, subquery),//
- new NV(SubqueryOp.Annotations.OPTIONAL,optional)//
- );
+ if (useHashJoin(queryHints)) {
+
+ final IVariable<?>[] joinVars =
+ gatherHashJoinVars(join, child);
+ final IConstraint[] joinConstraints =
+ gatherHashJoinConstraints(join, child);
+
+ final PipelineOp subquery = convert(
+ child, idFactory, db, queryEngine, queryHints);
+ final boolean optional = isOptional(child);
+ final int subqueryId = idFactory.incrementAndGet();
+
+ if (log.isInfoEnabled()) {
+ log.info("join vars: " + Arrays.toString(joinVars));
+ log.info("join constraints: " + Arrays.toString(joinConstraints));
+ }
+
+ left = new SubqueryHashJoinOp(new BOp[]{left},
+ new NV(Predicate.Annotations.BOP_ID, subqueryId),//
+ new NV(SubqueryOp.Annotations.SUBQUERY, subquery),//
+ new NV(SubqueryOp.Annotations.OPTIONAL,optional),//
+ new NV(SubqueryHashJoinOp.Annotations.PIPELINED, false),//
+ new NV(SubqueryHashJoinOp.Annotations.JOIN_VARS, joinVars),
+ new NV(SubqueryHashJoinOp.Annotations.CONSTRAINTS, joinConstraints)
+ );
+ } else {
+ final PipelineOp subquery = convert(
+ child, idFactory, db, queryEngine, queryHints);
+ final boolean optional = isOptional(child);
+ final int subqueryId = idFactory.incrementAndGet();
+ left = new SubqueryOp(new BOp[]{left},
+ new NV(Predicate.Annotations.BOP_ID, subqueryId),//
+ new NV(SubqueryOp.Annotations.SUBQUERY, subquery),//
+ new NV(SubqueryOp.Annotations.OPTIONAL,optional)//
+ );
+ }
if (log.isInfoEnabled()) {
- log.info("adding a subquery: " + subqueryId + "\n" + left);
+ log.info("adding a subquery:\n" + BOpUtility.toString2(left));
}
}
}
@@ -488,66 +516,8 @@
new LinkedHashMap<IVariable<?>, Collection<Predicate>>();
final Collection<IVariable<?>> boundByHashJoins =
new LinkedList<IVariable<?>>();
- if (true) { // maybe check query hints for this?
-
- int numSearches = 0;
- { // first count the searches
- for (IPredicate pred : preds) {
- if (isFreeTextSearch(pred))
- numSearches++;
- }
- }
- if (numSearches > 1) {
- { // collect them up
- final Iterator<Predicate> it = preds.iterator();
- while (it.hasNext()) {
- final Predicate pred = it.next();
- if (isFreeTextSearch(pred)) {
- // we're going to handle these separately
- it.remove();
- // create a hash group for this variable
- final IVariable v = (IVariable) pred.get(0);
- if (hashJoins.containsKey(v)) {
- throw new IllegalArgumentException(
- "multiple free text searches using the same variable!!");
- }
- final Collection<Predicate> hashGroup =
- new LinkedList<Predicate>();
- hashGroup.add(pred);
- hashJoins.put(v, hashGroup);
- // add this search variables to the list of known
- // bound variables
- boundByHashJoins.add(v);
- }
- }
- }
- { // collect up other predicates that use the search vars
- final Iterator<Predicate> it = preds.iterator();
- while (it.hasNext()) {
- final Predicate pred = it.next();
- // search always binds to a literal, which can only be
- // used as the 2nd arg (the object)
- final BOp obj = pred.get(2);
- if (obj instanceof IVariable<?>) {
- final IVariable<?> v = (IVariable<?>) obj;
- if (hashJoins.containsKey(v)) {
- // we're going to handle these separately
- it.remove();
- // add this predicate to the hash group
- hashJoins.get(v).add(pred);
- // add any other variables used by this tail to
- // the list of known bound variables
- for (BOp arg : pred.args()) {
- if (arg instanceof IVariable<?>) {
- boundByHashJoins.add((IVariable<?>) arg);
- }
- }
- }
- }
- }
- }
- }
-
+ if (useHashJoin(queryHints)) { // maybe check query hints for this?
+ gatherHashJoins(preds, hashJoins, boundByHashJoins);
}
final IVariable<?>[] required = group.getTree().getRequiredVars();
@@ -585,63 +555,32 @@
}
if (hashJoins.size() > 0) {
- final Set<IVariable<?>> lastVars = new LinkedHashSet<IVariable<?>>();
- final Set<IVariable<?>> joinVars = new LinkedHashSet<IVariable<?>>();
- int i = 0;
+ Collection<Predicate> lastGroup = null;
for (Collection<Predicate> hashGroup : hashJoins.values()) {
- joinVars.clear();
- if (lastVars.size() > 0) {
- for (Predicate pred : hashGroup) {
- for (BOp arg : pred.args()) {
- if (arg instanceof IVariable<?>) {
- final IVariable<?> v = (IVariable<?>) arg;
- if (lastVars.contains(v)) {
- joinVars.add(v);
- }
- }
- }
- }
- }
- lastVars.clear();
- for (Predicate pred : hashGroup) {
- for (BOp arg : pred.args()) {
- if (arg instanceof IVariable<?>) {
- final IVariable<?> v = (IVariable<?>) arg;
- lastVars.add(v);
- }
- }
- }
- if (i == 0) {
+ if (lastGroup == null) {
left = convert(hashGroup, constraints, left, knownBound,
idFactory, db, queryEngine, queryHints);
} else {
final PipelineOp subquery = convert(hashGroup, constraints,
null/*left*/, knownBound,
idFactory, db, queryEngine, queryHints);
- final PipelineOp slice = new SliceOp(new BOp[] { subquery }, NV.asMap(//
- new NV(BOp.Annotations.BOP_ID, idFactory.incrementAndGet()), //
- new NV(BOp.Annotations.EVALUATION_CONTEXT,
- BOpEvaluationContext.CONTROLLER),//
- new NV(PipelineOp.Annotations.SHARED_STATE, true)//
- ));
+ final IVariable<?>[] joinVars =
+ gatherHashJoinVars(lastGroup, hashGroup);
- final IVariable<?>[] joinVarsArray =
- joinVars.toArray(new IVariable[joinVars.size()]);
-
if (log.isInfoEnabled()) {
- log.info(Arrays.toString(joinVarsArray));
+ log.info(Arrays.toString(joinVars));
log.info(subquery);
}
left = new SubqueryHashJoinOp(new BOp[]{left},
new NV(Predicate.Annotations.BOP_ID, idFactory.incrementAndGet()),//
+ new NV(SubqueryHashJoinOp.Annotations.SUBQUERY, subquery),//
new NV(SubqueryHashJoinOp.Annotations.PIPELINED, false),//
- new NV(SubqueryHashJoinOp.Annotations.SUBQUERY, slice),//
- new NV(SubqueryHashJoinOp.Annotations.JOIN_VARS, joinVarsArray));
+ new NV(SubqueryHashJoinOp.Annotations.JOIN_VARS, joinVars));
}
- i++;
+ lastGroup = hashGroup;
}
}
@@ -673,7 +612,13 @@
return pred.getAccessPathExpander()
instanceof FreeTextSearchExpander;
}
-
+
+ /**
+ * Used by hashJoins. Temporary measure. Have to do this because normal
+ * rule2BOp would attach all the constraints to the last tail, which would
+ * cause this subquery to fail. Need to be smarter about pruning the
+ * constraints here and then we could just run through normal rule2BOp.
+ */
protected static final PipelineOp convert(
final Collection<Predicate> preds,
final Collection<IConstraint> constraints,
@@ -728,9 +673,194 @@
}
- return left;
+ final PipelineOp slice = new SliceOp(new BOp[] { left }, NV.asMap(//
+ new NV(BOp.Annotations.BOP_ID, idFactory.incrementAndGet()), //
+ new NV(BOp.Annotations.EVALUATION_CONTEXT,
+ BOpEvaluationContext.CONTROLLER),//
+ new NV(PipelineOp.Annotations.SHARED_STATE, true)//
+ ));
+
+ return slice;
}
+ protected static void gatherHashJoins(
+ final Collection<Predicate> preds,
+ final Map<IVariable<?>, Collection<Predicate>> hashJoins,
+ final Collection<IVariable<?>> boundByHashJoins) {
+
+ int numSearches = 0;
+ { // first count the searches
+ for (IPredicate pred : preds) {
+ if (isFreeTextSearch(pred))
+ numSearches++;
+ }
+ }
+ if (numSearches > 1) {
+ { // collect them up
+ final Iterator<Predicate> it = preds.iterator();
+ while (it.hasNext()) {
+ final Predicate pred = it.next();
+ if (isFreeTextSearch(pred)) {
+ // we're going to handle these separately
+ it.remove();
+ // create a hash group for this variable
+ final IVariable v = (IVariable) pred.get(0);
+ if (hashJoins.containsKey(v)) {
+ throw new IllegalArgumentException(
+ "multiple free text searches using the same variable!!");
+ }
+ final Collection<Predicate> hashGroup =
+ new LinkedList<Predicate>();
+ hashGroup.add(pred);
+ hashJoins.put(v, hashGroup);
+ // add this search variables to the list of known
+ // bound variables
+ boundByHashJoins.add(v);
+ }
+ }
+ }
+ { // collect up other predicates that use the search vars
+ final Iterator<Predicate> it = preds.iterator();
+ while (it.hasNext()) {
+ final Predicate pred = it.next();
+ // search always binds to a literal, which can only be
+ // used as the 2nd arg (the object)
+ final BOp obj = pred.get(2);
+ if (obj instanceof IVariable<?>) {
+ final IVariable<?> v = (IVariable<?>) obj;
+ if (hashJoins.containsKey(v)) {
+ // we're going to handle these separately
+ it.remove();
+ // add this predicate to the hash group
+ hashJoins.get(v).add(pred);
+ // add any other variables used by this tail to
+ // the list of known bound variables
+ for (BOp arg : pred.args()) {
+ if (arg instanceof IVariable<?>) {
+ boundByHashJoins.add((IVariable<?>) arg);
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+
+ }
+ protected static IVariable<?>[] gatherHashJoinVars(
+ final SOpGroup group1,
+ final SOpGroup group2) {
+
+ final Collection<Predicate> p1 = new LinkedList<Predicate>();
+ final Collection<Predicate> p2 = new LinkedList<Predicate>();
+
+ for (SOp sop : group1) {
+ final BOp bop = sop.getBOp();
+ if (bop instanceof Predicate)
+ p1.add((Predicate) bop);
+ }
+
+ for (SOp sop : group2) {
+ final BOp bop = sop.getBOp();
+ if (bop instanceof Predicate)
+ p2.add((Predicate) bop);
+ }
+
+ return gatherHashJoinVars(p1, p2);
+
+ }
+
+ protected static IVariable<?>[] gatherHashJoinVars(
+ final Collection<Predicate> group1,
+ final Collection<Predicate> group2) {
+
+ final Set<IVariable<?>> vars = new LinkedHashSet<IVariable<?>>();
+ final Set<IVariable<?>> joinVars = new LinkedHashSet<IVariable<?>>();
+
+ for (Predicate pred : group1) {
+ for (BOp arg : pred.args()) {
+ if (arg instanceof IVariable<?>) {
+ final IVariable<?> v = (IVariable<?>) arg;
+ vars.add(v);
+ }
+ }
+ }
+
+ if (vars.size() > 0) {
+ for (Predicate pred : group2) {
+ for (BOp arg : pred.args()) {
+ if (arg instanceof IVariable<?>) {
+ final IVariable<?> v = (IVariable<?>) arg;
+ if (vars.contains(v)) {
+ joinVars.add(v);
+ }
+ }
+ }
+ }
+ }
+
+ return joinVars.toArray(new IVariable<?>[joinVars.size()]);
+
+ }
+
+ protected static IConstraint[] gatherHashJoinConstraints(
+ final SOpGroup group1,
+ final SOpGroup group2) {
+
+ final Set<IVariable<?>> vars1 = new LinkedHashSet<IVariable<?>>();
+
+ for (SOp sop : group1) {
+ final BOp bop = sop.getBOp();
+ if (bop instanceof Predicate) {
+ final Predicate pred = (Predicate) bop;
+ for (BOp arg : pred.args()) {
+ if (arg instanceof IVariable<?>) {
+ final IVariable<?> v = (IVariable<?>) arg;
+ vars1.add(v);
+ }
+ }
+ }
+ }
+
+ // if the subquery has filters that use variables from the pipeline,
+ // we need to elevate those onto the HashJoin
+
+ final Collection<IConstraint> constraints = new LinkedList<IConstraint>();
+ final Collection<SOp> sopsToPrune = new LinkedList<SOp>();
+
+ for (SOp sop : group2) {
+ final BOp bop = sop.getBOp();
+ if (bop instanceof IConstraint) {
+ final IConstraint c = (IConstraint) bop;
+ final Iterator<IVariable<?>> vars = BOpUtility.getSpannedVariables(c);
+ while (vars.hasNext()) {
+ final IVariable<?> v = vars.next();
+ if (vars1.contains(v)) {
+ constraints.add(c);
+ sopsToPrune.add(sop);
+ }
+ }
+ }
+ }
+
+ group2.pruneSOps(sopsToPrune);
+
+ return constraints.toArray(new IConstraint[constraints.size()]);
+
+ }
+
+ protected static boolean useHashJoin(final Properties queryHints) {
+ final boolean hashJoin = Boolean.valueOf(queryHints.getProperty(
+ QueryHints.HASH_JOIN, QueryHints.DEFAULT_HASH_JOIN));
+ if (log.isInfoEnabled()) {
+ log.info(queryHints);
+ log.info(queryHints.getProperty(QueryHints.HASH_JOIN));
+ log.info("use hash join = " + hashJoin);
+ }
+ return hashJoin;
+ }
+
+
}
Modified: branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOpTree.java
===================================================================
--- branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOpTree.java 2011-04-06 21:27:45 UTC (rev 4375)
+++ branches/QUADS_QUERY_BRANCH/bigdata-sails/src/java/com/bigdata/rdf/sail/sop/SOpTree.java 2011-04-06 21:28:29 UTC (rev 4376)
@@ -165,6 +165,10 @@
return group == 0;
}
+ public void pruneSOps(final Collection<SOp> sopsToPrune) {
+ this.sops.removeAll(sopsToPrune);
+ }
+
}
public class SOpGroups implements Iterable<SOpGroup> {
Modified: branches/QUADS_QUERY_BRANCH/bigdata-sails/src/test/com/bigdata/rdf/sail/TestBOps.java
===================================================================
--- branches/QUADS_QUERY_BRANCH/bigdata-sails/src/test/com/bigdata/rdf/sail/TestBOps.java 2011-04-06 21:27:45 UTC (rev 4375)
+++ branches/QUADS_QUERY_BRANCH/bigdata-sails/src/test/com/bigdata/rdf/sail/TestBOps.java 2011-04-06 21:28:29 UTC (rev 4376)
@@ -70,7 +70,7 @@
props.setProperty(BigdataSail.Options.AXIOMS_CLASS, NoAxioms.class.getName());
props.setProperty(BigdataSail.Options.VOCABULARY_CLASS, NoVocabulary.class.getName());
props.setProperty(BigdataSail.Options.JUSTIFY, "false");
- props.setProperty(BigdataSail.Options.TEXT_INDEX, "false");
+ props.setProperty(BigdataSail.Options.TEXT_INDEX, "true");
return props;
@@ -452,4 +452,130 @@
}
+ public void testHashJoin() throws Exception {
+
+ final BigdataSail sail = getSail();
+ sail.initialize();
+ final BigdataSailRepository repo = new BigdataSailRepository(sail);
+ final BigdataSailRepositoryConnection cxn =
+ (BigdataSailRepositoryConnection) repo.getConnection();
+ cxn.setAutoCommit(false);
+
+ try {
+
+ final ValueFactory vf = sail.getValueFactory();
+
+ final LexiconRelation lex = sail.getDatabase().getLexiconRelation();
+
+ final String ns = BD.NAMESPACE;
+
+ URI mikeA = new URIImpl(ns+"MikeA");
+ URI mikeB = new URIImpl(ns+"MikeB");
+ URI bryan = new URIImpl(ns+"Bryan");
+ URI martyn = new URIImpl(ns+"Martyn");
+ URI person = new URIImpl(ns+"Person");
+ URI name = new URIImpl(ns+"name");
+ Literal l1 = new LiteralImpl("Mike");
+ Literal l2 = new LiteralImpl("Bryan");
+ Literal l3 = new LiteralImpl("Martyn");
+/**/
+ cxn.setNamespace("ns", ns);
+
+ cxn.add(mikeA, RDF.TYPE, person);
+ cxn.add(mikeA, name, l1);
+ cxn.add(mikeB, RDF.TYPE, person);
+ cxn.add(mikeB, name, l1);
+ cxn.add(bryan, RDF.TYPE, person);
+ cxn.add(bryan, name, l2);
+ cxn.add(martyn, RDF.TYPE, person);
+ cxn.add(martyn, name, l3);
+
+ /*
+ * Note: The either flush() or commit() is required to flush the
+ * statement buffers to the database before executing any operations
+ * that go around the sail.
+ */
+ cxn.flush();//commit();
+ cxn.commit();//
+
+ if (log.isInfoEnabled()) {
+ log.info("\n" + sail.getDatabase().dumpStore());
+ }
+
+ {
+
+// String query =
+// "PREFIX "+QueryHints.PREFIX+": <"+QueryHints.NAMESPACE+QueryHints.HASH_JOIN+"=true> " +
+// "PREFIX rdf: <"+RDF.NAMESPACE+"> " +
+// "PREFIX rdfs: <"+RDFS.NAMESPACE+"> " +
+// "PREFIX bds: <"+BD.SEARCH_NAMESPACE+"> " +
+// "PREFIX ns: <"+ns+"> " +
+//
+// "select distinct ?s1 ?s2 " +
+//// "select distinct ?s1 " +
+// "WHERE { " +
+// " ?o1 bds:search \"m*\" ." +
+// " ?s1 ns:name ?o1 . " +
+// " ?s1 rdf:type ns:Person . " +
+// " ?s1 ns:name ?name . " +
+// " OPTIONAL { " +
+// " ?o2 bds:search \"m*\" ." +
+// " ?s2 ns:name ?o2 . " +
+// " ?s2 rdf:type ns:Person . " +
+// " ?s2 ns:name ?name . " +
+// " filter(?s1 != ?s2) . " +
+// " } " +
+//// " filter(!bound(?s2) || ?s1 != ?s2) . " +
+// "}";
+
+ String query =
+ "PREFIX "+QueryHints.PREFIX+": <"+QueryHints.NAMESPACE+QueryHints.HASH_JOIN+"=true> " +
+ "PREFIX rdf: <"+RDF.NAMESPACE+"> " +
+ "PREFIX rdfs: <"+RDFS.NAMESPACE+"> " +
+ "PREFIX bds: <"+BD.SEARCH_NAMESPACE+"> " +
+ "PREFIX ns: <"+ns+"> " +
+
+ "select distinct ?s1 ?s2 " +
+ "WHERE { " +
+ " ?s1 rdf:type ns:Person . " +
+ " ?s1 ns:name ?name . " +
+ " OPTIONAL { " +
+ " ?s2 rdf:type ns:Person . " +
+ " ?s2 ns:name ?name . " +
+ " filter(?s1 != ?s2) . " +
+ " } " +
+ "}";
+
+
+ final TupleQuery tupleQuery =
+ cxn.prepareTupleQuery(QueryLanguage.SPARQL, query);
+ TupleQueryResult result = tupleQuery.evaluate();
+
+ while (result.hasNext()) {
+ System.err.println(result.next());
+ }
+
+// Collection<BindingSet> solution = new LinkedList<BindingSet>();
+// solution.add(createBindingSet(new Binding[] {
+// new BindingImpl("s", mike),
+// new BindingImpl("p", RDFS.LABEL),
+// new BindingImpl("label", l1)
+// }));
+// solution.add(createBindingSet(new Binding[] {
+// new BindingImpl("s", bryan),
+// new BindingImpl("p", RDFS.COMMENT),
+// new BindingImpl("label", l2)
+// }));
+//
+// compare(result, solution);
+
+ }
+
+ } finally {
+ cxn.close();
+ sail.__tearDownUnitTest();
+ }
+
+ }
+
}
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