Eclipse RDF4J

Milestone number 2 of the upcoming 6.0.0 release of RDF4J is now available for download.

RDF4J 6.0.0 is a major release of the RDF4J framework. This second milestone continues the work from Milestone 1 with RDF 1.2 and SPARQL 1.2 support, new safeguards for long-running queries, query-planning improvements, FedX optimizations, and deployment updates.

Please note that RDF4J 6.0.0-M2 requires Java 25.

Some of the highlights covered in this second milestone:

• RDF 1.2 and SPARQL 1.2 support in parsers, writers, the model API, and query evaluation
• Query circuit breakers that protect server and workbench query execution under unsafe JVM memory pressure
• Configurable slow-query logging for Sail-backed repositories, focused on time to first result
• FedX grouped source selection, reducing remote source-selection requests for larger federations
• Query optimizer work including sketch-based join planning, cascade-style planners, LMDB cardinality-estimation improvements, and plan-comparison tooling
• Updated Docker images for Jetty 12 and Tomcat 11 on Java 25, plus Docker run documentation updates
• New vocabulary modules for EU, annotation, and bibliographic vocabularies, plus additional PROV-O inverse properties

This milestone build is not yet feature-complete, but we are putting it out to receive early feedback on all the improvements we have put in.

• issues fixed in 6.0.0 Milestone 2
• issues planned for 6.0.0

Upgrade notes

RDF 1.2 and SPARQL 1.2

RDF4J 6.0.0-M2 adds broad support for RDF 1.2 and SPARQL 1.2 (GH-5327). This includes RDF 1.2 parser and writer updates for Turtle, TriG, N-Triples, N-Quads, and RDF/XML, SPARQL 1.2 grammar and evaluation changes, and conformance-test coverage for the new syntax and behavior.

The model API now uses RDF 1.2 triple-term terminology. Legacy RDF-star parser/writer formats and names have been replaced by the corresponding triple-term APIs and formats. Triple terms are supported in object position, matching RDF 1.2 semantics.

Support is not yet complete for every store. The SPARQL 1.2 conformance suite is enabled for MemoryStore, while NativeStore and LMDBStore still have known gaps for triple-term and base-direction support.

Query execution safeguards

RDF4J now includes query circuit breakers for server and workbench query execution (GH-5809). These monitor JVM memory pressure, reject or abort query work when pressure becomes unsafe, release in-flight query resources, and expose breaker status for operators.

Sail-backed repositories can also be configured to log slow queries (GH-5819). The implementation tracks query context through Sail evaluation and logs queries that exceed a configured threshold before producing their first result.

Query planning and LMDB

The query optimizer has received new sketch-based, unified, and cascade-style planning work (GH-5720, PR-5785, PR-5796), including runtime telemetry and plan-comparison tooling. LMDB cardinality estimation has also been improved with a page-walking estimator that reads LMDB data files directly (GH-5686).

FedX

FedX source selection can now group remote source checks per endpoint (GH-5813). For larger federations, this reduces source-selection round trips from one ASK query per statement-pattern/endpoint pair to grouped SELECT queries using BIND(EXISTS { ... }). The optimization is enabled by default and can be disabled through FedXConfig#withEnableGroupedSourceSelection(false).

The FedX module also received cleanup for deprecated and unwired 6.0-era code paths (GH-5828).

Docker and deployment

The Docker setup now targets Java 25 application-server images: Jetty 12 with EE11 modules and Tomcat 11 (GH-5801). The developer testing guide and Server/Workbench deployment guide now document the docker/run.sh workflow and Docker Compose usage.

Vocabularies

RDF4J now ships additional vocabulary modules for EU data-portal and dataspace vocabularies, annotation vocabularies, and bibliographic vocabularies (GH-5709). The PROV-O vocabulary also includes the suggested inverse properties listed by PROV-O (GH-5706).

Links

• Download RDF4J

Milestone number 1 of the upcoming 6.0.0 release of RDF4J is now available for download.

RDF4J 6.0.0 is a major release of the RDF4J framework, focusing on dependency upgrades, LMDB improvements, and HTTP client improvements.

Please note that RDF4J 6.0.0-M1 requires Java 25.

Some of the highlights covered in this first milestone:

• Upgrade to Java 25 as the minimally-required version of Java
• Introduction of a pluggable HTTP client SPI with Apache HttpComponents 5 and JDK built-in backends
• Migration from Apache HttpComponents 4 to the new HTTP client facade

This milestone build is not yet feature-complete, but we are putting it out to receive early feedback on all the improvements we have put in.

RDF4J 5.3.1 is now available. This is a patch release fixing 2 bugs.

For more details, have a look at the release notes.