GH-4315 support sparql lateral by m-alreeni · Pull Request #5853 · eclipse-rdf4j/rdf4j

m-alreeni · 2026-06-03T11:42:20Z

GitHub issue resolved: #4315

Briefly describe the changes proposed in this PR:

Core implementation of SPARQL lateral join functionality

Query Evaluation: handle lateral joins and iterating over lateral join results
Parser Updates: to recognize lateral join syntax and build lateral join expressions
Extended query model visitors to support lateral join traversal

PR Author Checklist (see the contributor guidelines for more details):

my pull request is self-contained
I've added tests for the changes I made
I've applied code formatting (you can use mvn process-resources to format from the command line)
I've squashed my commits where necessary
every commit message starts with the issue number (GH-xxxx) followed by a meaningful description of the change

kenwenzel · 2026-06-03T12:03:42Z

Why is this commit rebase to rdf 1.2 in the middle?

m-alreeni · 2026-06-03T12:45:31Z

Why is this commit rebase to rdf 1.2 in the middle?

The message is wrong and confusing. I'll correct it

kenwenzel · 2026-06-08T09:11:19Z

@hmottestad Do you also think that this can be merged?

Copilot

Pull request overview

Adds core support for SPARQL 1.2-style LATERAL graph patterns to RDF4J, spanning parsing, query model, rendering, and evaluation, with accompanying compliance tests/resources.

Changes:

Extend the SPARQL parser/AST builder to recognize LATERAL { ... } and construct a new query algebra node.
Introduce Lateral as a BinaryTupleOperator, wire it into visitors/rendering, and add evaluation support via a dedicated iterator/evaluation step.
Add new SPARQL 1.2 testsuite resources and a JUnit dynamic test class for LATERAL behavior.

Reviewed changes

Copilot reviewed 33 out of 34 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
testsuites/sparql/src/main/resources/testcases-sparql-1.2/manifest-all.ttl	Includes the lateral tests manifest in the SPARQL 1.2 testsuite manifest.
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/manifest.ttl	Declares LATERAL tests (currently only lateral-01/02).
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/data.ttl	Test data used by LATERAL query evaluation tests.
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-01.rq	LATERAL test query (LIMIT).
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-01.srx	Expected results for lateral-01.
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-02.rq	LATERAL test query (OPTIONAL).
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-02.srx	Expected results for lateral-02.
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-03.rq	Additional LATERAL test query (multiple results).
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-03.srx	Expected results for lateral-03.
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-04.rq	Additional LATERAL test query (UNION).
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-04.srx	Expected results for lateral-04.
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-05.rq	Additional LATERAL test query (subselect + filter).
testsuites/sparql/src/main/resources/testcases-sparql-1.2/lateral/lateral-05.srx	Expected results for lateral-05.
testsuites/sparql/src/main/java/org/eclipse/rdf4j/testsuite/sparql/tests/LateralTest.java	Adds dynamic JUnit tests for basic LATERAL evaluation scenarios.
testsuites/sparql/src/main/java/org/eclipse/rdf4j/testsuite/sparql/RepositorySPARQLComplianceTestSuite.java	Registers LATERAL tests into the repository compliance suite.
core/queryrender/src/main/java/org/eclipse/rdf4j/queryrender/sparql/SparqlTupleExprRenderer.java	Adds rendering support for the new `Lateral` algebra node.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/TupleExprBuilder.java	Builds a `Lateral` tuple expression from the parsed AST.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/ast/SyntaxTreeBuilderVisitor.java	Extends AST visitor interface with `ASTLateralGraphPattern`.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/ast/SyntaxTreeBuilderTreeConstants.java	Adds AST node id/name for lateral graph pattern.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/ast/SyntaxTreeBuilderDefaultVisitor.java	Adds default visitation for the new lateral AST node.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/ast/SyntaxTreeBuilderConstants.java	Adds the `LATERAL` token and keyword mapping.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/ast/SyntaxTreeBuilder.java	Generated parser changes to parse `LATERAL { ... }`.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/ast/sparql.jjt	Grammar update to introduce `LATERAL` graph patterns.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/ast/ASTLateralGraphPattern.java	New generated AST node type for lateral graph patterns.
core/queryparser/sparql/src/main/java/org/eclipse/rdf4j/query/parser/sparql/AbstractASTVisitor.java	Ensures AST traversal includes the lateral graph pattern node.
core/queryalgebra/model/src/main/java/org/eclipse/rdf4j/query/algebra/QueryModelVisitor.java	Adds `meet(Lateral)` to the query model visitor API.
core/queryalgebra/model/src/main/java/org/eclipse/rdf4j/query/algebra/Lateral.java	Introduces the `Lateral` query algebra operator.
core/queryalgebra/model/src/main/java/org/eclipse/rdf4j/query/algebra/helpers/StatementPatternVisitor.java	Traversal support for the new algebra node.
core/queryalgebra/model/src/main/java/org/eclipse/rdf4j/query/algebra/helpers/AbstractSimpleQueryModelVisitor.java	Default visitor support for `Lateral`.
core/queryalgebra/model/src/main/java/org/eclipse/rdf4j/query/algebra/helpers/AbstractQueryModelVisitor.java	Default visitor support for `Lateral`.
core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/LateralIterator.java	New iterator to evaluate RHS per LHS binding set.
core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/impl/evaluationsteps/LateralQueryEvaluationStep.java	New evaluation step to hook `Lateral` into strategy precompilation.
core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/impl/DefaultEvaluationStrategy.java	Wires `Lateral` into runtime evaluation and precompilation.

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+	@Override
+	public Object visit(ASTLateralGraphPattern node, Object data) throws VisitorException {
+		GraphPattern parentGP = graphPattern;
+
+		// The left argument is the current graph pattern so far
+		TupleExpr leftArg = graphPattern.buildTupleExpr();
+
+		// Create a new graph pattern for the lateral block
+		graphPattern = new GraphPattern(parentGP);
+		node.jjtGetChild(0).jjtAccept(this, null);
+		TupleExpr rightArg = graphPattern.buildTupleExpr();
+
+		// Create the lateral join
+		Lateral lateral = new Lateral(leftArg, rightArg);
+		parentGP.addRequiredTE(lateral);
+		graphPattern = parentGP;
+
+		return null;
+	}


+	@Override
+	public Set<String> getAssuredBindingNames() {
+		return getLeftArg().getAssuredBindingNames();
+	}


+    rdfs:label "Lateral" ;
+    mf:entries
+    (
+    :lateral-01
+    :lateral-02


+			// Should have 4 results: subject1 with 2 alternatives, subject2 with 1,
+			// subject3 with none


kenwenzel · 2026-06-17T10:57:09Z

@m-alreeni Please take a look at the review above and try to fix the problems (if any).

…Pattern, fix assured-binding information, extend tests

…ateral-05.rq

hmottestad · 2026-06-18T05:28:01Z

I have been reviewing and fixing issues here: #5875

m-alreeni added 2 commits June 3, 2026 14:36

eclipse-rdf4jGH-4315 support of lateral join

1046826

eclipse-rdf4jGH-4315 fix copyright header

f049d99

m-alreeni force-pushed the GH-4315-support-sparql-lateral branch from 7310d71 to f049d99 Compare June 3, 2026 13:13

aschwarte10 requested a review from Copilot June 17, 2026 10:11

Copilot started reviewing on behalf of aschwarte10 June 17, 2026 10:12 View session

Copilot AI reviewed Jun 17, 2026

View reviewed changes

m-alreeni added 2 commits June 17, 2026 16:17

eclipse-rdf4jGH-4315 handle ASTLateralGraphPattern like ASTMinusGraph…

e194032

…Pattern, fix assured-binding information, extend tests

eclipse-rdf4jGH-4315 fix test files: lateral-03.srx, lateral-04.rq, l…

06078dd

…ateral-05.rq

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GH-4315 support sparql lateral#5853

GH-4315 support sparql lateral#5853
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m-alreeni commented Jun 3, 2026

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		// Should have 4 results: subject1 with 2 alternatives, subject2 with 1,
		// subject3 with none

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m-alreeni commented Jun 3, 2026

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Pull request overview

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kenwenzel commented Jun 17, 2026

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hmottestad commented Jun 18, 2026

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