Oct 172014

Trentino, Italy:  19-23 October 2014

SYSTAP’s Chief Scientist and Co-Founder, Bryan Thompson, is presenting SYSTAP’s MapGraph technology during the industry track at the the 13th Annual International Semantic Web Conference (ISWC 2014).  SYSTAP is a Gold Sponsor for ISWC 2014, the premier international forum for the Semantic Web / Linked Data Community. Here, scientists, industry specialists, and practitioners meet to discuss the future of practical, scalable, user-friendly, and game changing solutions.

SYSTAP’s MapGraph is a new and disruptive technology for organizations that need to process large graphs in near-real time.  It cost effectively brings the capabilities of High Performance Computing (HPC) to your organization’s biggest and most time critical graph challenges.  MapGraph provides a familiar vertex-centric graph programming model, but its GPU acceleration is 100s of times faster than competing CPU-only technologies and up to 100,000 times faster than graph technologies based on key-value stores such as HBase, Titan, and Accumulo. MapGraph runs on one GPU or a cluster of GPUs.  With MapGraph on 64 NVIDIA K40 GPUs, you can traverse a scale-free graph of 4.3 billion directed edges in .13 seconds for a throughput of 32 Billion Traversed Edges Per Second (32 GTEPS).  Learn more at http://MapGraph.io.

Sep 262014

This is a minor release of bigdata(R) with critical security and bug fixes.

Bigdata is a horizontally-scaled, open-source architecture for indexed data with an emphasis on RDF capable of loading 1B triples in under one hour on a 15 node cluster. Bigdata operates in both a single machine mode (Journal), highly available replication cluster mode (HAJournalServer), and a horizontally sharded cluster mode (BigdataFederation). The Journal provides fast scalable ACID indexed storage for very large data sets, up to 50 billion triples / quads. The HAJournalServer adds replication, online backup, horizontal scaling of query, and high availability. The federation provides fast scalable shard-wise parallel indexed storage using dynamic sharding and shard-wise ACID updates and incremental cluster size growth. Both platforms support fully concurrent readers with snapshot isolation.

Distributed processing offers greater throughput but does not reduce query or update latency. Choose the Journal when the anticipated scale and throughput requirements permit. Choose the HAJournalServer for high availability and linear scaling in query throughput. Choose the BigdataFederation when the administrative and machine overhead associated with operating a cluster is an acceptable tradeoff to have essentially unlimited data scaling and throughput.

See [1,2,8] for instructions on installing bigdata(R), [4] for the javadoc, and [3,5,6] for news, questions, and the latest developments. For more information about SYSTAP, LLC and bigdata, see [7].

Starting with the 1.0.0 release, we offer a WAR artifact [8] for easy installation of the single machine RDF database. For custom development and cluster installations we recommend checking out the code from SVN using the tag for this release. The code will build automatically under eclipse. You can also build the code using the ant script. The cluster installer requires the use of the ant script.

Starting with the 1.3.0 release, we offer a tarball artifact [10] for easy installation of the HA replication cluster.

You can download the WAR (standalone) or HA artifacts from:


You can checkout this release from:


Critical or otherwise of note in this minor release:

– Stored query facility (#989).
– Improved locality for small allocation slots (#986).
– Improved scalability for RWStore (#936).
– Various improvements for the workbench.
– Various improvements for property graphs.
– Critical bug fix for hasStatements() for unisolated indices (#855, #1005).
– Critical bug fix for ConcurrentWeakValueHashMap (#1004).
– Critical bug fix for query timeouts (#772, #865).
– Critical bug fix for RWStore (#973).
– Security fix for Apache commons-fileupload (#1010).

New features in 1.3.x:

– Java 7 is now required.
– High availability [10].
– High availability load balancer.
– New RDF/SPARQL workbench.
– Blueprints API.
– RDF Graph Mining Service (GASService) [12].
– Reification Done Right (RDR) support [11].
– Property Path performance enhancements.
– Plus numerous other bug fixes and performance enhancements.

Feature summary:

– Highly Available Replication Clusters (HAJournalServer [10])
– Single machine data storage to ~50B triples/quads (RWStore);
– Clustered data storage is essentially unlimited (BigdataFederation);
– Simple embedded and/or webapp deployment (NanoSparqlServer);
– Triples, quads, or triples with provenance (SIDs);
– Fast RDFS+ inference and truth maintenance;
– Fast 100% native SPARQL 1.1 evaluation;
– Integrated “analytic” query package;
– %100 Java memory manager leverages the JVM native heap (no GC);

Road map [3]:

– Column-wise indexing;
– Runtime Query Optimizer for quads;
– Performance optimization for scale-out clusters; and
– Simplified deployment, configuration, and administration for scale-out clusters.

Change log:

Note: Versions with (*) MAY require data migration. For details, see [9].


– http://trac.bigdata.com/ticket/1016 (Jetty/LBS issues when deployed as WAR under tomcat)
– http://trac.bigdata.com/ticket/1010 (Upgrade apache http components to 1.3.1 (security))
– http://trac.bigdata.com/ticket/1005 (Invalidate BTree objects if error occurs during eviction)
– http://trac.bigdata.com/ticket/1004 (Concurrent binding problem)
– http://trac.bigdata.com/ticket/1002 (Concurrency issues in JVMHashJoinUtility caused by MAX_PARALLEL query hint override)
– http://trac.bigdata.com/ticket/1000 (Add configuration option to turn off bottom-up evaluation)
– http://trac.bigdata.com/ticket/999 (Extend BigdataSailFactory to take arbitrary properties)
– http://trac.bigdata.com/ticket/998 (SPARQL Update through BigdataGraph)
– http://trac.bigdata.com/ticket/996 (Add custom prefix support for query results)
– http://trac.bigdata.com/ticket/995 (Allow general purpose SPARQL queries through BigdataGraph)
– http://trac.bigdata.com/ticket/992 (Deadlock between AbstractRunningQuery.cancel(), QueryLog.log(), and ArbitraryLengthPathTask)
– http://trac.bigdata.com/ticket/990 (Query hints not recognized in FILTERs)
– http://trac.bigdata.com/ticket/989 (Stored query service)
– http://trac.bigdata.com/ticket/988 (Bad performance for FILTER EXISTS)
– http://trac.bigdata.com/ticket/987 (maven build is broken)
– http://trac.bigdata.com/ticket/986 (Improve locality for small allocation slots)
– http://trac.bigdata.com/ticket/985 (Deadlock in BigdataTriplePatternMaterializer)
– http://trac.bigdata.com/ticket/975 (HA Health Status Page)
– http://trac.bigdata.com/ticket/974 (Name2Addr.indexNameScan(prefix) uses scan + filter)
– http://trac.bigdata.com/ticket/973 (RWStore.commit() should be more defensive)
– http://trac.bigdata.com/ticket/971 (Clarify HTTP Status codes for CREATE NAMESPACE operation)
– http://trac.bigdata.com/ticket/968 (no link to wiki from workbench)
– http://trac.bigdata.com/ticket/966 (Failed to get namespace under concurrent update)
– http://trac.bigdata.com/ticket/965 (Can not run LBS mode with HA1 setup)
– http://trac.bigdata.com/ticket/961 (Clone/modify namespace to create a new one)
– http://trac.bigdata.com/ticket/960 (Export namespace properties in XML/Java properties text format)
– http://trac.bigdata.com/ticket/938 (HA Load Balancer)
– http://trac.bigdata.com/ticket/936 (Support larger metabits allocations)
– http://trac.bigdata.com/ticket/932 (Bigdata/Rexster integration)
– http://trac.bigdata.com/ticket/919 (Formatted Layout for Status pages)
– http://trac.bigdata.com/ticket/899 (REST API Query Cancellation)
– http://trac.bigdata.com/ticket/885 (Panels do not appear on startup in Firefox)
– http://trac.bigdata.com/ticket/884 (Executing a new query should clear the old query results from the console)
– http://trac.bigdata.com/ticket/882 (Abbreviate URIs that can be namespaced with one of the defined common namespaces)
– http://trac.bigdata.com/ticket/880 (Can’t explore an absolute URI with < >)
– http://trac.bigdata.com/ticket/878 (Explore page looks weird when empty)
– http://trac.bigdata.com/ticket/873 (Allow user to go use browser back & forward buttons to view explore history)
– http://trac.bigdata.com/ticket/865 (OutOfMemoryError instead of Timeout for SPARQL Property Paths)
– http://trac.bigdata.com/ticket/858 (Change explore URLs to include URI being clicked so user can see what they’ve clicked on before)
– http://trac.bigdata.com/ticket/855 (AssertionError: Child does not have persistent identity)
– http://trac.bigdata.com/ticket/850 (Search functionality in workbench)
– http://trac.bigdata.com/ticket/847 (Query results panel should recognize well known namespaces for easier reading)
– http://trac.bigdata.com/ticket/845 (Display the properties for a namespace)
– http://trac.bigdata.com/ticket/843 (Create new tabs for status & performance counters, and add per namespace service/VoID description links)
– http://trac.bigdata.com/ticket/837 (Configurator for new namespaces)
– http://trac.bigdata.com/ticket/836 (Allow user to create namespace in the workbench)
– http://trac.bigdata.com/ticket/830 (Output RDF data from queries in table format)
– http://trac.bigdata.com/ticket/829 (Export query results)
– http://trac.bigdata.com/ticket/828 (Save selected namespace in browser)
– http://trac.bigdata.com/ticket/827 (Explore tab in workbench)
– http://trac.bigdata.com/ticket/826 (Create shortcut to execute load/query)
– http://trac.bigdata.com/ticket/823 (Disable textarea when a large file is selected)
– http://trac.bigdata.com/ticket/820 (Allow non-file:// URLs to be loaded)
– http://trac.bigdata.com/ticket/819 (Retrieve default namespace on page load)
– http://trac.bigdata.com/ticket/772 (Query timeout only checked at operator start/stop)
– http://trac.bigdata.com/ticket/765 (order by expr skips invalid expressions)
– http://trac.bigdata.com/ticket/587 (JSP page to configure KBs)
– http://trac.bigdata.com/ticket/343 (Stochastic assert in AbstractBTree#writeNodeOrLeaf() in CI)


– http://trac.bigdata.com/ticket/242 (Deadlines do not play well with GROUP_BY, ORDER_BY, etc.)
– http://trac.bigdata.com/ticket/256 (Amortize RTO cost)
– http://trac.bigdata.com/ticket/257 (Support BOP fragments in the RTO.)
– http://trac.bigdata.com/ticket/258 (Integrate RTO into SAIL)
– http://trac.bigdata.com/ticket/259 (Dynamically increase RTO sampling limit.)
– http://trac.bigdata.com/ticket/526 (Reification done right)
– http://trac.bigdata.com/ticket/580 (Problem with the bigdata RDF/XML parser with sids)
– http://trac.bigdata.com/ticket/622 (NSS using jetty+windows can lose connections (windows only; jdk 6/7 bug))
– http://trac.bigdata.com/ticket/624 (HA Load Balancer)
– http://trac.bigdata.com/ticket/629 (Graph processing API)
– http://trac.bigdata.com/ticket/721 (Support HA1 configurations)
– http://trac.bigdata.com/ticket/730 (Allow configuration of embedded NSS jetty server using jetty-web.xml)
– http://trac.bigdata.com/ticket/759 (multiple filters interfere)
– http://trac.bigdata.com/ticket/763 (Stochastic results with Analytic Query Mode)
– http://trac.bigdata.com/ticket/774 (Converge on Java 7.)
– http://trac.bigdata.com/ticket/779 (Resynchronization of socket level write replication protocol (HA))
– http://trac.bigdata.com/ticket/780 (Incremental or asynchronous purge of HALog files)
– http://trac.bigdata.com/ticket/782 (Wrong serialization version)
– http://trac.bigdata.com/ticket/784 (Describe Limit/offset don’t work as expected)
– http://trac.bigdata.com/ticket/787 (Update documentations and samples, they are OUTDATED)
– http://trac.bigdata.com/ticket/788 (Name2Addr does not report all root causes if the commit fails.)
– http://trac.bigdata.com/ticket/789 (ant task to build sesame fails, docs for setting up bigdata for sesame are ancient)
– http://trac.bigdata.com/ticket/790 (should not be pruning any children)
– http://trac.bigdata.com/ticket/791 (Clean up query hints)
– http://trac.bigdata.com/ticket/793 (Explain reports incorrect value for opCount)
– http://trac.bigdata.com/ticket/796 (Filter assigned to sub-query by query generator is dropped from evaluation)
– http://trac.bigdata.com/ticket/797 (add sbt setup to getting started wiki)
– http://trac.bigdata.com/ticket/798 (Solution order not always preserved)
– http://trac.bigdata.com/ticket/799 (mis-optimation of quad pattern vs triple pattern)
– http://trac.bigdata.com/ticket/802 (Optimize DatatypeFactory instantiation in DateTimeExtension)
– http://trac.bigdata.com/ticket/803 (prefixMatch does not work in full text search)
– http://trac.bigdata.com/ticket/804 (update bug deleting quads)
– http://trac.bigdata.com/ticket/806 (Incorrect AST generated for OPTIONAL { SELECT })
– http://trac.bigdata.com/ticket/808 (Wildcard search in bigdata for type suggessions)
– http://trac.bigdata.com/ticket/810 (Expose GAS API as SPARQL SERVICE)
– http://trac.bigdata.com/ticket/815 (RDR query does too much work)
– http://trac.bigdata.com/ticket/816 (Wildcard projection ignores variables inside a SERVICE call.)
– http://trac.bigdata.com/ticket/817 (Unexplained increase in journal size)
– http://trac.bigdata.com/ticket/821 (Reject large files, rather then storing them in a hidden variable)
– http://trac.bigdata.com/ticket/831 (UNION with filter issue)
– http://trac.bigdata.com/ticket/841 (Using “VALUES” in a query returns lexical error)
– http://trac.bigdata.com/ticket/848 (Fix SPARQL Results JSON writer to write the RDR syntax)
– http://trac.bigdata.com/ticket/849 (Create writers that support the RDR syntax)
– http://trac.bigdata.com/ticket/851 (RDR GAS interface)
– http://trac.bigdata.com/ticket/852 (RemoteRepository.cancel() does not consume the HTTP response entity.)
– http://trac.bigdata.com/ticket/853 (Follower does not accept POST of idempotent operations (HA))
– http://trac.bigdata.com/ticket/854 (Allow override of maximum length before converting an HTTP GET to an HTTP POST)
– http://trac.bigdata.com/ticket/855 (AssertionError: Child does not have persistent identity)
– http://trac.bigdata.com/ticket/862 (Create parser for JSON SPARQL Results)
– http://trac.bigdata.com/ticket/863 (HA1 commit failure)
– http://trac.bigdata.com/ticket/866 (Batch remove API for the SAIL)
– http://trac.bigdata.com/ticket/867 (NSS concurrency problem with list namespaces and create namespace)
– http://trac.bigdata.com/ticket/869 (HA5 test suite)
– http://trac.bigdata.com/ticket/872 (Full text index range count optimization)
– http://trac.bigdata.com/ticket/874 (FILTER not applied when there is UNION in the same join group)
– http://trac.bigdata.com/ticket/876 (When I upload a file I want to see the filename.)
– http://trac.bigdata.com/ticket/877 (RDF Format selector is invisible)
– http://trac.bigdata.com/ticket/883 (CANCEL Query fails on non-default kb namespace on HA follower.)
– http://trac.bigdata.com/ticket/886 (Provide workaround for bad reverse DNS setups.)
– http://trac.bigdata.com/ticket/887 (BIND is leaving a variable unbound)
– http://trac.bigdata.com/ticket/892 (HAJournalServer does not die if zookeeper is not running)
– http://trac.bigdata.com/ticket/893 (large sparql insert optimization slow?)
– http://trac.bigdata.com/ticket/894 (unnecessary synchronization)
– http://trac.bigdata.com/ticket/895 (stack overflow in populateStatsMap)
– http://trac.bigdata.com/ticket/902 (Update Basic Bigdata Chef Cookbook)
– http://trac.bigdata.com/ticket/904 (AssertionError: PropertyPathNode got to ASTJoinOrderByType.optimizeJoinGroup)
– http://trac.bigdata.com/ticket/905 (unsound combo query optimization: union + filter)
– http://trac.bigdata.com/ticket/906 (DC Prefix Button Appends “

– http://trac.bigdata.com/ticket/907 (Add a quick-start ant task for the BD Server “ant start”)
– http://trac.bigdata.com/ticket/912 (Provide a configurable IAnalyzerFactory)
– http://trac.bigdata.com/ticket/913 (Blueprints API Implementation)
– http://trac.bigdata.com/ticket/914 (Settable timeout on SPARQL Query (REST API))
– http://trac.bigdata.com/ticket/915 (DefaultAnalyzerFactory issues)
– http://trac.bigdata.com/ticket/920 (Content negotiation orders accept header scores in reverse)
– http://trac.bigdata.com/ticket/939 (NSS does not start from command line: bigdata-war/src not found.)
– http://trac.bigdata.com/ticket/940 (ProxyServlet in web.xml breaks tomcat WAR (HA LBS)


– http://trac.bigdata.com/ticket/530 (Journal HA)
– http://trac.bigdata.com/ticket/621 (Coalesce write cache records and install reads in cache)
– http://trac.bigdata.com/ticket/623 (HA TXS)
– http://trac.bigdata.com/ticket/639 (Remove triple-buffering in RWStore)
– http://trac.bigdata.com/ticket/645 (HA backup)
– http://trac.bigdata.com/ticket/646 (River not compatible with newer 1.6.0 and 1.7.0 JVMs)
– http://trac.bigdata.com/ticket/648 (Add a custom function to use full text index for filtering.)
– http://trac.bigdata.com/ticket/651 (RWS test failure)
– http://trac.bigdata.com/ticket/652 (Compress write cache blocks for replication and in HALogs)
– http://trac.bigdata.com/ticket/662 (Latency on followers during commit on leader)
– http://trac.bigdata.com/ticket/663 (Issue with OPTIONAL blocks)
– http://trac.bigdata.com/ticket/664 (RWStore needs post-commit protocol)
– http://trac.bigdata.com/ticket/665 (HA3 LOAD non-responsive with node failure)
– http://trac.bigdata.com/ticket/666 (Occasional CI deadlock in HALogWriter testConcurrentRWWriterReader)
– http://trac.bigdata.com/ticket/670 (Accumulating HALog files cause latency for HA commit)
– http://trac.bigdata.com/ticket/671 (Query on follower fails during UPDATE on leader)
– http://trac.bigdata.com/ticket/673 (DGC in release time consensus protocol causes native thread leak in HAJournalServer at each commit)
– http://trac.bigdata.com/ticket/674 (WCS write cache compaction causes errors in RWS postHACommit())
– http://trac.bigdata.com/ticket/676 (Bad patterns for timeout computations)
– http://trac.bigdata.com/ticket/677 (HA deadlock under UPDATE + QUERY)
– http://trac.bigdata.com/ticket/678 (DGC Thread and Open File Leaks: sendHALogForWriteSet())
– http://trac.bigdata.com/ticket/679 (HAJournalServer can not restart due to logically empty log file)
– http://trac.bigdata.com/ticket/681 (HAJournalServer deadlock: pipelineRemove() and getLeaderId())
– http://trac.bigdata.com/ticket/684 (Optimization with skos altLabel)
– http://trac.bigdata.com/ticket/686 (Consensus protocol does not detect clock skew correctly)
– http://trac.bigdata.com/ticket/687 (HAJournalServer Cache not populated)
– http://trac.bigdata.com/ticket/689 (Missing URL encoding in RemoteRepositoryManager)
– http://trac.bigdata.com/ticket/690 (Error when using the alias “a” instead of rdf:type for a multipart insert)
– http://trac.bigdata.com/ticket/691 (Failed to re-interrupt thread in HAJournalServer)
– http://trac.bigdata.com/ticket/692 (Failed to re-interrupt thread)
– http://trac.bigdata.com/ticket/693 (OneOrMorePath SPARQL property path expression ignored)
– http://trac.bigdata.com/ticket/694 (Transparently cancel update/query in RemoteRepository)
– http://trac.bigdata.com/ticket/695 (HAJournalServer reports “follower” but is in SeekConsensus and is not participating in commits.)
– http://trac.bigdata.com/ticket/701 (Problems in BackgroundTupleResult)
– http://trac.bigdata.com/ticket/702 (InvocationTargetException on /namespace call)
– http://trac.bigdata.com/ticket/704 (ask does not return json)
– http://trac.bigdata.com/ticket/705 (Race between QueryEngine.putIfAbsent() and shutdownNow())
– http://trac.bigdata.com/ticket/706 (MultiSourceSequentialCloseableIterator.nextSource() can throw NPE)
– http://trac.bigdata.com/ticket/707 (BlockingBuffer.close() does not unblock threads)
– http://trac.bigdata.com/ticket/708 (BIND heisenbug – race condition on select query with BIND)
– http://trac.bigdata.com/ticket/711 (sparql protocol: mime type application/sparql-query)
– http://trac.bigdata.com/ticket/712 (SELECT ?x { OPTIONAL { ?x eg:doesNotExist eg:doesNotExist } } incorrect)
– http://trac.bigdata.com/ticket/715 (Interrupt of thread submitting a query for evaluation does not always terminate the AbstractRunningQuery)
– http://trac.bigdata.com/ticket/716 (Verify that IRunningQuery instances (and nested queries) are correctly cancelled when interrupted)
– http://trac.bigdata.com/ticket/718 (HAJournalServer needs to handle ZK client connection loss)
– http://trac.bigdata.com/ticket/720 (HA3 simultaneous service start failure)
– http://trac.bigdata.com/ticket/723 (HA asynchronous tasks must be canceled when invariants are changed)
– http://trac.bigdata.com/ticket/725 (FILTER EXISTS in subselect)
– http://trac.bigdata.com/ticket/726 (Logically empty HALog for committed transaction)
– http://trac.bigdata.com/ticket/727 (DELETE/INSERT fails with OPTIONAL non-matching WHERE)
– http://trac.bigdata.com/ticket/728 (Refactor to create HAClient)
– http://trac.bigdata.com/ticket/729 (ant bundleJar not working)
– http://trac.bigdata.com/ticket/731 (CBD and Update leads to 500 status code)
– http://trac.bigdata.com/ticket/732 (describe statement limit does not work)
– http://trac.bigdata.com/ticket/733 (Range optimizer not optimizing Slice service)
– http://trac.bigdata.com/ticket/734 (two property paths interfere)
– http://trac.bigdata.com/ticket/736 (MIN() malfunction)
– http://trac.bigdata.com/ticket/737 (class cast exception)
– http://trac.bigdata.com/ticket/739 (Inconsistent treatment of bind and optional property path)
– http://trac.bigdata.com/ticket/741 (ctc-striterators should build as independent top-level project (Apache2))
– http://trac.bigdata.com/ticket/743 (AbstractTripleStore.destroy() does not filter for correct prefix)
– http://trac.bigdata.com/ticket/746 (Assertion error)
– http://trac.bigdata.com/ticket/747 (BOUND bug)
– http://trac.bigdata.com/ticket/748 (incorrect join with subselect renaming vars)
– http://trac.bigdata.com/ticket/754 (Failure to setup SERVICE hook and changeLog for Unisolated and Read/Write connections)
– http://trac.bigdata.com/ticket/755 (Concurrent QuorumActors can interfere leading to failure to progress)
– http://trac.bigdata.com/ticket/756 (order by and group_concat)
– http://trac.bigdata.com/ticket/760 (Code review on 2-phase commit protocol)
– http://trac.bigdata.com/ticket/764 (RESYNC failure (HA))
– http://trac.bigdata.com/ticket/770 (alpp ordering)
– http://trac.bigdata.com/ticket/772 (Query timeout only checked at operator start/stop.)
– http://trac.bigdata.com/ticket/776 (Closed as duplicate of #490)
– http://trac.bigdata.com/ticket/778 (HA Leader fail results in transient problem with allocations on other services)
– http://trac.bigdata.com/ticket/783 (Operator Alerts (HA))


– http://trac.bigdata.com/ticket/777 (ConcurrentModificationException in ASTComplexOptionalOptimizer)


– http://trac.bigdata.com/ticket/168 (Maven Build)
– http://trac.bigdata.com/ticket/196 (Journal leaks memory).
– http://trac.bigdata.com/ticket/235 (Occasional deadlock in CI runs in com.bigdata.io.writecache.TestAll)
– http://trac.bigdata.com/ticket/312 (CI (mock) quorums deadlock)
– http://trac.bigdata.com/ticket/405 (Optimize hash join for subgroups with no incoming bound vars.)
– http://trac.bigdata.com/ticket/412 (StaticAnalysis#getDefinitelyBound() ignores exogenous variables.)
– http://trac.bigdata.com/ticket/485 (RDFS Plus Profile)
– http://trac.bigdata.com/ticket/495 (SPARQL 1.1 Property Paths)
– http://trac.bigdata.com/ticket/519 (Negative parser tests)
– http://trac.bigdata.com/ticket/531 (SPARQL UPDATE for SOLUTION SETS)
– http://trac.bigdata.com/ticket/535 (Optimize JOIN VARS for Sub-Selects)
– http://trac.bigdata.com/ticket/555 (Support PSOutputStream/InputStream at IRawStore)
– http://trac.bigdata.com/ticket/559 (Use RDFFormat.NQUADS as the format identifier for the NQuads parser)
– http://trac.bigdata.com/ticket/570 (MemoryManager Journal does not implement all methods).
– http://trac.bigdata.com/ticket/575 (NSS Admin API)
– http://trac.bigdata.com/ticket/577 (DESCRIBE with OFFSET/LIMIT needs to use sub-select)
– http://trac.bigdata.com/ticket/578 (Concise Bounded Description (CBD))
– http://trac.bigdata.com/ticket/579 (CONSTRUCT should use distinct SPO filter)
– http://trac.bigdata.com/ticket/583 (VoID in ServiceDescription)
– http://trac.bigdata.com/ticket/586 (RWStore immedateFree() not removing Checkpoint addresses from the historical index cache.)
– http://trac.bigdata.com/ticket/590 (nxparser fails with uppercase language tag)
– http://trac.bigdata.com/ticket/592 (Optimize RWStore allocator sizes)
– http://trac.bigdata.com/ticket/593 (Ugrade to Sesame 2.6.10)
– http://trac.bigdata.com/ticket/594 (WAR was deployed using TRIPLES rather than QUADS by default)
– http://trac.bigdata.com/ticket/596 (Change web.xml parameter names to be consistent with Jini/River)
– http://trac.bigdata.com/ticket/597 (SPARQL UPDATE LISTENER)
– http://trac.bigdata.com/ticket/598 (B+Tree branching factor and HTree addressBits are confused in their NodeSerializer implementations)
– http://trac.bigdata.com/ticket/599 (BlobIV for blank node : NotMaterializedException)
– http://trac.bigdata.com/ticket/600 (BlobIV collision counter hits false limit.)
– http://trac.bigdata.com/ticket/601 (Log uncaught exceptions)
– http://trac.bigdata.com/ticket/602 (RWStore does not discard logged deletes on reset())
– http://trac.bigdata.com/ticket/607 (History service / index)
– http://trac.bigdata.com/ticket/608 (LOG BlockingBuffer not progressing at INFO or lower level)
– http://trac.bigdata.com/ticket/609 (bigdata-ganglia is required dependency for Journal)
– http://trac.bigdata.com/ticket/611 (The code that processes SPARQL Update has a typo)
– http://trac.bigdata.com/ticket/612 (Bigdata scale-up depends on zookeper)
– http://trac.bigdata.com/ticket/613 (SPARQL UPDATE response inlines large DELETE or INSERT triple graphs)
– http://trac.bigdata.com/ticket/614 (static join optimizer does not get ordering right when multiple tails share vars with ancestry)
– http://trac.bigdata.com/ticket/615 (AST2BOpUtility wraps UNION with an unnecessary hash join)
– http://trac.bigdata.com/ticket/616 (Row store read/update not isolated on Journal)
– http://trac.bigdata.com/ticket/617 (Concurrent KB create fails with “No axioms defined?”)
– http://trac.bigdata.com/ticket/618 (DirectBufferPool.poolCapacity maximum of 2GB)
– http://trac.bigdata.com/ticket/619 (RemoteRepository class should use application/x-www-form-urlencoded for large POST requests)
– http://trac.bigdata.com/ticket/620 (UpdateServlet fails to parse MIMEType when doing conneg.)
– http://trac.bigdata.com/ticket/626 (Expose performance counters for read-only indices)
– http://trac.bigdata.com/ticket/627 (Environment variable override for NSS properties file)
– http://trac.bigdata.com/ticket/628 (Create a bigdata-client jar for the NSS REST API)
– http://trac.bigdata.com/ticket/631 (ClassCastException in SIDs mode query)
– http://trac.bigdata.com/ticket/632 (NotMaterializedException when a SERVICE call needs variables that are provided as query input bindings)
– http://trac.bigdata.com/ticket/633 (ClassCastException when binding non-uri values to a variable that occurs in predicate position)
– http://trac.bigdata.com/ticket/638 (Change DEFAULT_MIN_RELEASE_AGE to 1ms)
– http://trac.bigdata.com/ticket/640 (Conditionally rollback() BigdataSailConnection if dirty)
– http://trac.bigdata.com/ticket/642 (Property paths do not work inside of exists/not exists filters)
– http://trac.bigdata.com/ticket/643 (Add web.xml parameters to lock down public NSS end points)
– http://trac.bigdata.com/ticket/644 (Bigdata2Sesame2BindingSetIterator can fail to notice asynchronous close())
– http://trac.bigdata.com/ticket/650 (Can not POST RDF to a graph using REST API)
– http://trac.bigdata.com/ticket/654 (Rare AssertionError in WriteCache.clearAddrMap())
– http://trac.bigdata.com/ticket/655 (SPARQL REGEX operator does not perform case-folding correctly for Unicode data)
– http://trac.bigdata.com/ticket/656 (InFactory bug when IN args consist of a single literal)
– http://trac.bigdata.com/ticket/647 (SIDs mode creates unnecessary hash join for GRAPH group patterns)
– http://trac.bigdata.com/ticket/667 (Provide NanoSparqlServer initialization hook)
– http://trac.bigdata.com/ticket/669 (Doubly nested subqueries yield no results with LIMIT)
– http://trac.bigdata.com/ticket/675 (Flush indices in parallel during checkpoint to reduce IO latency)
– http://trac.bigdata.com/ticket/682 (AtomicRowFilter UnsupportedOperationException)


– http://trac.bigdata.com/ticket/586 (RWStore immedateFree() not removing Checkpoint addresses from the historical index cache.)
– http://trac.bigdata.com/ticket/602 (RWStore does not discard logged deletes on reset())
– http://trac.bigdata.com/ticket/603 (Prepare critical maintenance release as branch of 1.2.1)


– http://trac.bigdata.com/ticket/533 (Review materialization for inline IVs)
– http://trac.bigdata.com/ticket/539 (NotMaterializedException with REGEX and Vocab)
– http://trac.bigdata.com/ticket/540 (SPARQL UPDATE using NSS via index.html)
– http://trac.bigdata.com/ticket/541 (MemoryManaged backed Journal mode)
– http://trac.bigdata.com/ticket/546 (Index cache for Journal)
– http://trac.bigdata.com/ticket/549 (BTree can not be cast to Name2Addr (MemStore recycler))
– http://trac.bigdata.com/ticket/550 (NPE in Leaf.getKey() : root cause was user error)
– http://trac.bigdata.com/ticket/558 (SPARQL INSERT not working in same request after INSERT DATA)
– http://trac.bigdata.com/ticket/562 (Sub-select in INSERT cause NPE in UpdateExprBuilder)
– http://trac.bigdata.com/ticket/563 (DISTINCT ORDER BY)
– http://trac.bigdata.com/ticket/567 (Failure to set cached value on IV results in incorrect behavior for complex UPDATE operation)
– http://trac.bigdata.com/ticket/568 (DELETE WHERE fails with Java AssertionError)
– http://trac.bigdata.com/ticket/569 (LOAD-CREATE-LOAD using virgin journal fails with “Graph exists” exception)
– http://trac.bigdata.com/ticket/571 (DELETE/INSERT WHERE handling of blank nodes)
– http://trac.bigdata.com/ticket/573 (NullPointerException when attempting to INSERT DATA containing a blank node)

1.2.0: (*)

– http://trac.bigdata.com/ticket/92 (Monitoring webapp)
– http://trac.bigdata.com/ticket/267 (Support evaluation of 3rd party operators)
– http://trac.bigdata.com/ticket/337 (Compact and efficient movement of binding sets between nodes.)
– http://trac.bigdata.com/ticket/433 (Cluster leaks threads under read-only index operations: DGC thread leak)
– http://trac.bigdata.com/ticket/437 (Thread-local cache combined with unbounded thread pools causes effective memory leak: termCache memory leak & thread-local buffers)
– http://trac.bigdata.com/ticket/438 (KeyBeforePartitionException on cluster)
– http://trac.bigdata.com/ticket/439 (Class loader problem)
– http://trac.bigdata.com/ticket/441 (Ganglia integration)
– http://trac.bigdata.com/ticket/443 (Logger for RWStore transaction service and recycler)
– http://trac.bigdata.com/ticket/444 (SPARQL query can fail to notice when IRunningQuery.isDone() on cluster)
– http://trac.bigdata.com/ticket/445 (RWStore does not track tx release correctly)
– http://trac.bigdata.com/ticket/446 (HTTP Repostory broken with bigdata 1.1.0)
– http://trac.bigdata.com/ticket/448 (SPARQL 1.1 UPDATE)
– http://trac.bigdata.com/ticket/449 (SPARQL 1.1 Federation extension)
– http://trac.bigdata.com/ticket/451 (Serialization error in SIDs mode on cluster)
– http://trac.bigdata.com/ticket/454 (Global Row Store Read on Cluster uses Tx)
– http://trac.bigdata.com/ticket/456 (IExtension implementations do point lookups on lexicon)
– http://trac.bigdata.com/ticket/457 (“No such index” on cluster under concurrent query workload)
– http://trac.bigdata.com/ticket/458 (Java level deadlock in DS)
– http://trac.bigdata.com/ticket/460 (Uncaught interrupt resolving RDF terms)
– http://trac.bigdata.com/ticket/461 (KeyAfterPartitionException / KeyBeforePartitionException on cluster)
– http://trac.bigdata.com/ticket/463 (NoSuchVocabularyItem with LUBMVocabulary for DerivedNumericsExtension)
– http://trac.bigdata.com/ticket/464 (Query statistics do not update correctly on cluster)
– http://trac.bigdata.com/ticket/465 (Too many GRS reads on cluster)
– http://trac.bigdata.com/ticket/469 (Sail does not flush assertion buffers before query)
– http://trac.bigdata.com/ticket/472 (acceptTaskService pool size on cluster)
– http://trac.bigdata.com/ticket/475 (Optimize serialization for query messages on cluster)
– http://trac.bigdata.com/ticket/476 (Test suite for writeCheckpoint() and recycling for BTree/HTree)
– http://trac.bigdata.com/ticket/478 (Cluster does not map input solution(s) across shards)
– http://trac.bigdata.com/ticket/480 (Error releasing deferred frees using 1.0.6 against a 1.0.4 journal)
– http://trac.bigdata.com/ticket/481 (PhysicalAddressResolutionException against 1.0.6)
– http://trac.bigdata.com/ticket/482 (RWStore reset() should be thread-safe for concurrent readers)
– http://trac.bigdata.com/ticket/484 (Java API for NanoSparqlServer REST API)
– http://trac.bigdata.com/ticket/491 (AbstractTripleStore.destroy() does not clear the locator cache)
– http://trac.bigdata.com/ticket/492 (Empty chunk in ThickChunkMessage (cluster))
– http://trac.bigdata.com/ticket/493 (Virtual Graphs)
– http://trac.bigdata.com/ticket/496 (Sesame 2.6.3)
– http://trac.bigdata.com/ticket/497 (Implement STRBEFORE, STRAFTER, and REPLACE)
– http://trac.bigdata.com/ticket/498 (Bring bigdata RDF/XML parser up to openrdf 2.6.3.)
– http://trac.bigdata.com/ticket/500 (SPARQL 1.1 Service Description)
– http://www.openrdf.org/issues/browse/SES-884 (Aggregation with an solution set as input should produce an empty solution as output)
– http://www.openrdf.org/issues/browse/SES-862 (Incorrect error handling for SPARQL aggregation; fix in 2.6.1)
– http://www.openrdf.org/issues/browse/SES-873 (Order the same Blank Nodes together in ORDER BY)
– http://trac.bigdata.com/ticket/501 (SPARQL 1.1 BINDINGS are ignored)
– http://trac.bigdata.com/ticket/503 (Bigdata2Sesame2BindingSetIterator throws QueryEvaluationException were it should throw NoSuchElementException)
– http://trac.bigdata.com/ticket/504 (UNION with Empty Group Pattern)
– http://trac.bigdata.com/ticket/505 (Exception when using SPARQL sort & statement identifiers)
– http://trac.bigdata.com/ticket/506 (Load, closure and query performance in 1.1.x versus 1.0.x)
– http://trac.bigdata.com/ticket/508 (LIMIT causes hash join utility to log errors)
– http://trac.bigdata.com/ticket/513 (Expose the LexiconConfiguration to Function BOPs)
– http://trac.bigdata.com/ticket/515 (Query with two “FILTER NOT EXISTS” expressions returns no results)
– http://trac.bigdata.com/ticket/516 (REGEXBOp should cache the Pattern when it is a constant)
– http://trac.bigdata.com/ticket/517 (Java 7 Compiler Compatibility)
– http://trac.bigdata.com/ticket/518 (Review function bop subclass hierarchy, optimize datatype bop, etc.)
– http://trac.bigdata.com/ticket/520 (CONSTRUCT WHERE shortcut)
– http://trac.bigdata.com/ticket/521 (Incremental materialization of Tuple and Graph query results)
– http://trac.bigdata.com/ticket/525 (Modify the IChangeLog interface to support multiple agents)
– http://trac.bigdata.com/ticket/527 (Expose timestamp of LexiconRelation to function bops)
– http://trac.bigdata.com/ticket/532 (ClassCastException during hash join (can not be cast to TermId))
– http://trac.bigdata.com/ticket/533 (Review materialization for inline IVs)
– http://trac.bigdata.com/ticket/534 (BSBM BI Q5 error using MERGE JOIN)

1.1.0 (*)

– http://trac.bigdata.com/ticket/23 (Lexicon joins)
– http://trac.bigdata.com/ticket/109 (Store large literals as “blobs”)
– http://trac.bigdata.com/ticket/181 (Scale-out LUBM “how to” in wiki and build.xml are out of date.)
– http://trac.bigdata.com/ticket/203 (Implement an persistence capable hash table to support analytic query)
– http://trac.bigdata.com/ticket/209 (AccessPath should visit binding sets rather than elements for high level query.)
– http://trac.bigdata.com/ticket/227 (SliceOp appears to be necessary when operator plan should suffice without)
– http://trac.bigdata.com/ticket/232 (Bottom-up evaluation semantics).
– http://trac.bigdata.com/ticket/246 (Derived xsd numeric data types must be inlined as extension types.)
– http://trac.bigdata.com/ticket/254 (Revisit pruning of intermediate variable bindings during query execution)
– http://trac.bigdata.com/ticket/261 (Lift conditions out of subqueries.)
– http://trac.bigdata.com/ticket/300 (Native ORDER BY)
– http://trac.bigdata.com/ticket/324 (Inline predeclared URIs and namespaces in 2-3 bytes)
– http://trac.bigdata.com/ticket/330 (NanoSparqlServer does not locate “html” resources when run from jar)
– http://trac.bigdata.com/ticket/334 (Support inlining of unicode data in the statement indices.)
– http://trac.bigdata.com/ticket/364 (Scalable default graph evaluation)
– http://trac.bigdata.com/ticket/368 (Prune variable bindings during query evaluation)
– http://trac.bigdata.com/ticket/370 (Direct translation of openrdf AST to bigdata AST)
– http://trac.bigdata.com/ticket/373 (Fix StrBOp and other IValueExpressions)
– http://trac.bigdata.com/ticket/377 (Optimize OPTIONALs with multiple statement patterns.)
– http://trac.bigdata.com/ticket/380 (Native SPARQL evaluation on cluster)
– http://trac.bigdata.com/ticket/387 (Cluster does not compute closure)
– http://trac.bigdata.com/ticket/395 (HTree hash join performance)
– http://trac.bigdata.com/ticket/401 (inline xsd:unsigned datatypes)
– http://trac.bigdata.com/ticket/408 (xsd:string cast fails for non-numeric data)
– http://trac.bigdata.com/ticket/421 (New query hints model.)
– http://trac.bigdata.com/ticket/431 (Use of read-only tx per query defeats cache on cluster)


– http://trac.bigdata.com/ticket/217 (BTreeCounters does not track bytes released)
– http://trac.bigdata.com/ticket/269 (Refactor performance counters using accessor interface)
– http://trac.bigdata.com/ticket/329 (B+Tree should delete bloom filter when it is disabled.)
– http://trac.bigdata.com/ticket/372 (RWStore does not prune the CommitRecordIndex)
– http://trac.bigdata.com/ticket/375 (Persistent memory leaks (RWStore/DISK))
– http://trac.bigdata.com/ticket/385 (FastRDFValueCoder2: ArrayIndexOutOfBoundsException)
– http://trac.bigdata.com/ticket/391 (Release age advanced on WORM mode journal)
– http://trac.bigdata.com/ticket/392 (Add a DELETE by access path method to the NanoSparqlServer)
– http://trac.bigdata.com/ticket/393 (Add “context-uri” request parameter to specify the default context for INSERT in the REST API)
– http://trac.bigdata.com/ticket/394 (log4j configuration error message in WAR deployment)
– http://trac.bigdata.com/ticket/399 (Add a fast range count method to the REST API)
– http://trac.bigdata.com/ticket/422 (Support temp triple store wrapped by a BigdataSail)
– http://trac.bigdata.com/ticket/424 (NQuads support for NanoSparqlServer)
– http://trac.bigdata.com/ticket/425 (Bug fix to DEFAULT_RDF_FORMAT for bulk data loader in scale-out)
– http://trac.bigdata.com/ticket/426 (Support either lockfile (procmail) and dotlockfile (liblockfile1) in scale-out)
– http://trac.bigdata.com/ticket/427 (BigdataSail#getReadOnlyConnection() race condition with concurrent commit)
– http://trac.bigdata.com/ticket/435 (Address is 0L)
– http://trac.bigdata.com/ticket/436 (TestMROWTransactions failure in CI)


– http://trac.bigdata.com/ticket/32 (Query time expansion of (foo rdf:type rdfs:Resource) drags in SPORelation for scale-out.)
– http://trac.bigdata.com/ticket/181 (Scale-out LUBM “how to” in wiki and build.xml are out of date.)
– http://trac.bigdata.com/ticket/356 (Query not terminated by error.)
– http://trac.bigdata.com/ticket/359 (NamedGraph pattern fails to bind graph variable if only one binding exists.)
– http://trac.bigdata.com/ticket/361 (IRunningQuery not closed promptly.)
– http://trac.bigdata.com/ticket/371 (DataLoader fails to load resources available from the classpath.)
– http://trac.bigdata.com/ticket/376 (Support for the streaming of bigdata IBindingSets into a sparql query.)
– http://trac.bigdata.com/ticket/378 (ClosedByInterruptException during heavy query mix.)
– http://trac.bigdata.com/ticket/379 (NotSerializableException for SPOAccessPath.)
– http://trac.bigdata.com/ticket/382 (Change dependencies to Apache River 2.2.0)

1.0.1 (*)

– http://trac.bigdata.com/ticket/107 (Unicode clean schema names in the sparse row store).
– http://trac.bigdata.com/ticket/124 (TermIdEncoder should use more bits for scale-out).
– http://trac.bigdata.com/ticket/225 (OSX requires specialized performance counter collection classes).
– http://trac.bigdata.com/ticket/348 (BigdataValueFactory.asValue() must return new instance when DummyIV is used).
– http://trac.bigdata.com/ticket/349 (TermIdEncoder limits Journal to 2B distinct RDF Values per triple/quad store instance).
– http://trac.bigdata.com/ticket/351 (SPO not Serializable exception in SIDS mode (scale-out)).
– http://trac.bigdata.com/ticket/352 (ClassCastException when querying with binding-values that are not known to the database).
– http://trac.bigdata.com/ticket/353 (UnsupportedOperatorException for some SPARQL queries).
– http://trac.bigdata.com/ticket/355 (Query failure when comparing with non materialized value).
– http://trac.bigdata.com/ticket/357 (RWStore reports “FixedAllocator returning null address, with freeBits”.)
– http://trac.bigdata.com/ticket/359 (NamedGraph pattern fails to bind graph variable if only one binding exists.)
– http://trac.bigdata.com/ticket/362 (log4j – slf4j bridge.)

For more information about bigdata(R), please see the following links:

[1] http://wiki.bigdata.com/wiki/index.php/Main_Page
[2] http://wiki.bigdata.com/wiki/index.php/GettingStarted
[3] http://wiki.bigdata.com/wiki/index.php/Roadmap
[4] http://www.bigdata.com/bigdata/docs/api/
[5] http://sourceforge.net/projects/bigdata/
[6] http://www.bigdata.com/blog
[7] http://www.systap.com/bigdata.htm
[8] http://sourceforge.net/projects/bigdata/files/bigdata/
[9] http://wiki.bigdata.com/wiki/index.php/DataMigration
[10] http://wiki.bigdata.com/wiki/index.php/HAJournalServer
[11] http://www.bigdata.com/whitepapers/reifSPARQL.pdf
[12] http://wiki.bigdata.com/wiki/index.php/RDF_GAS_API

About bigdata:

Bigdata(R) is a horizontally-scaled, general purpose storage and computing fabric for ordered data (B+Trees), designed to operate on either a single server or a cluster of commodity hardware. Bigdata(R) uses dynamically partitioned key-range shards in order to remove any realistic scaling limits – in principle, bigdata(R) may be deployed on 10s, 100s, or even thousands of machines and new capacity may be added incrementally without requiring the full reload of all data. The bigdata(R) RDF database supports RDFS and OWL Lite reasoning, high-level query (SPARQL), and datum level provenance.

Aug 072014

There is a commit working its way through CI right now in the 1.3 maintenance branch. This commit puts in place a mechanism to inline many different types of URIs directly into the statement indices, including UUIDs. The new mechanism and how to use it are described in the ticket:


This change will be backward compatible with old journals, but obviously to take advantage of it you would need to reload the data so that URIs can be inlined. It should be possible to inline all sorts of URIs with this new mechanism. Inlining terms is a great way to save space in the indices and improve performance, as it eliminates the need to round-trips terms through the dictionary indices.

Jul 302014

We have been working on a multi-GPU version of MapGraph.  The new code performs Breadth First Search over 4.3 billion directed edges on a scale-free graph at 29 Billion Traversed Edges Per Second (29 GTEPS) on a cluster with 64 K20 GPUs.   Using the platform described in the technical report, MapGraph is 3x faster than the YarcData(r) Urika(r) appliance at what we estimate to be 1/3 of the hardware cost for a 9x improvement in price/performance. Using the K40 GPUs, a cluster of 81 GPUs has nearly 1 TB of RAM, the maximum available for the YarcData appliance.  However, unlike YarcData, the MapGraph solution can scale to even larger GPU deployments.

Contact us directly if you are interested in custom applications of this emerging disruptive technology.
Cray, YarcData, and Urika are trademarks of Cray, Inc.

Jul 182014

We have made some significant changes in the RWStore to improve the throughput for incremental transactions.  These changes address a problem where scattered IOs lead to a bottleneck in the disk system and also reduce the total #of bytes written to the disk.  The benefit can be very large for SATA disks, but it is substantial for SAS and SSD disks as well.  How substantial?  We observe throughput increasing by 3-4x over our baseline configurations for incremental data load of LUBM.

First, a bit of background.  Bigdata uses clustered indices for everything.  This includes the dictionary indices (TERM2ID, ID2TERM, and BLOBS) and the statement indices (SPO, POS, and OSP).  In quads mode, we use a different set of clustered indices for the statements (SPOC, POSC, etc).  Some of these indices naturally have good locality on update, especially the ID2TERM, SPO/SPOC indices, and the CSPO index (in quads mode).  These indices will always show good locality for transaction updates since we sort the index writes and then write on the indices in ascending order for maximum cache effect.

However, the statement indices that start with O (OSP, OCSP) always have very poor locality. This is because the Object position varies quite a bit across the statements in any given transaction update. This means that most index pages for the OSP/OCSP indices that are touched by a transaction will be dirtied by a single tuple during the transaction.  The same problem exists to a somewhat lessor extend with the P indices (POS, POCS, PCSO).

The TERM2ID index normally has decent locality, but if you are using UUIDs or similar globally unique identifiers in your URLs, then that will cause a scattered update profile on the TERM2ID index.  What we recommend for a best practice here is to create an inline IV type for your UUID-based URLs such that they will be automatically converted into fixed length IVs (18 bytes – 1 flags, 1 extension byte, and 16 bytes for the UUID).  This will remove the UUID-based URLs completely from the dictionary indices. They will be inlined into the statement indices instead as 18 bytes per URL.

The solution for these scattered updates is to (a) reduce the branching factors to target a 1024 byte page size (or less) for the indices with scattered update patterns (this reduces the #of bytes written to the disk); (b) enable the small slot optimization in the RWStore (this ensures good locality on the disk for the indices with the scattered update patterns; and (c) optionally reduce the write retention queue capacity for those indices (this reduces GC overhead associated with those indices – there is little benefit to a high retention queue if the access pattern for the index is scattered).

Small slots processing will be in the 1.3.2 release.  To enable small slot processing before then, you need to be using branches/BIGDATA_RELEASE_1_3_0 at r8568 or above.

The current advice to reduce IO in update transactions is:

  • Default the BTree branching factor of 256 .
  • Set the default BTree retention to 4000.
  • Enable the small slot optimization.
  • Override branching factors for OSP/OCSP and POS/POSC to 64.

To do this, you need to modify your properties file and/or specify the following when creating a new namespace within bigdata.

# Enable small slot optimization.
# Set the default B+Tree branching factor.
# Set the default B+Tree retention queue capacity.

The branching factor overrides need to be made for each index in each triple store or quad store instance. For example, the following property will override the OSP index branching factor for the default bigdata namespace, which is “kb”.  You need to do this for each namespace that you create.


The small slot optimization will take effect when you restart bigdata.  The changes to the write retention queue capacity and the branching factors will only take effect when a new triple store or quad store instance is created.

We still need to examine the impact on query performance from changing these various branching factors.  In principle, the latency of the index is proportional to log(p), where p is the height of the B+Tree.  Thus, it should be a sub-linear relationship. Testing on BSBM 100M reveals that reduced branching factors for the indices with scattered update patterns (as recommended above) does not impact query performance.

Jul 172014

We are pleased to announce that Bayerische Staatsbibliothek is in production
with bigdata powering their public SPARQL end point.

A description of the provided dataset can be found at the Datahub: http://datahub.io/dataset/b3kat.
Some details about the Bavarian State Library: http://www.bsb-muenchen.de/en/about-us/the-library-in-brief/

For more information, please contact lod@bsb-muenchen.de .

Jun 182014

One of the major successes that people point to for the semantic web is the semantic publishing platform at the BBC.  We are pleased to announce that Yahoo7 has rolled out a semantic publishing platform based on bigdata. Read more about the Yahoo7 experience and how they have doubled their users time on site using semantic publishing and bigdata.


This is just one more in a list of major semantic web success stories built around the bigdata platform:

  • EMC – data and host mangement solutions in data centers around the world (slides from SEMTECH 2012, NYC)
  • Autodesk –  graph management for the Autodesk cloud ecosystem (SEMTECH 2013, SF)
  • Yahoo7 – semantic publishing (today)

Contact us if you want to be the next success.


Jun 162014

Olaf Hartig has developed a formal model of the “Reification Done Right” concepts [1].  The model formalizes an extension to both RDF (known as RDF*) and SPARQL (known as SPARQL*).  These extensions define a backwards compatible relationship between the RDF data model and the SPARQL query language and an alternative perspective on RDF Reification. The RDF* and SPARQL* models are introduced and formally described in  Foundations of an Alternative Approach to Reification in RDF.

The key contributions of this paper are:

  • Formal extensions of the RDF data model and the SPARQL algebra that reconciles RDF Reification with statement-level metadata;
  • An extended syntax for TURTLE that permits easy interchange of statements about statements.
  • An extended syntax for SPARQL that make it easy to express queries and data for statements about statements.
  • Rewrite rules that may be used to translate RDF* into RDF and SPARQL* into SPARQL.

RDF* and SPARQL* allow statements to appear as Subjects or Objects in other statements.  Statements about these “inline” statements can be interpreted as if they were statements about statements.  The paper shows that this is equivalent to statements about reified RDF statement models. For example, the following statements declare a name for some resource “:bob”, an age for :bob, and provide assertions about how and where that age was obtained:

:bob foaf:name "Bob" .
<<:bob foaf:age 23>> dct:creator <http://example.com/crawlers#c1>
                     dct:source <http://example.net/homepage-listing.html> .

and then queried using:

SELECT ?age ?src WHERE {
   ?bob foaf:name "Bob" .
   <<?bob foaf:age ?age>> dct:source ?src .

In both cases the << >> notation denotes a statement appearing as the Subject or Object of another statement.  Further, statements may become bound to variables as shown in this alternative syntax:

SELECT ?age ?src WHERE {
   ?bob foaf:name "Bob" .
   BIND( <<?bob foaf:age ?age>> AS ?t ) .
   ?t dct:source ?src .

The paper proves that these examples are equivalent using RDF Reification. That is RDF Reification already gives us a mechanism to represent, interchange, and query statements about statements.  However, the paper also shows that statements about statements may be modeled and queried within the database in a wide variety of different physical schemas that allow great efficiency and data density when compared to naive indexing of RDF statement models.  This gives database designers enormous freedom in how they choose to represent those statements about statements and helps to counter the impression that RDF databases are necessarily bad for problems requiring link attributes.  For example, any of the following physical schema could be used to represent these statements about statements:

  • Explicitly model the statements about statements as reified RDF statement models;
  • Associating a “statement identifier” with each statement in the database and then using it to represent statements about statements;
  • Directly embed the statement “:bob foaf:age 23″ into the representation of each statement about that statement (inlining within the statement indices using variable length and recursively embedded encodings of the Subject and Object of a statement); and
  • Extending the (s,p,o) table to include additional columns, in this case dct:creator and dct:source.  This can be advantageous when some metadata predicate has a maximum cardinality of one and is used for most statements in the database (for example, this could be used to create an efficient bi-temporal database with statement-level metadata columns for the business-start-time, business-end-time, and transaction-time for each assertion).

By clarifying the formal semantics of RDF Reification and offering a simplified syntax for data interchange, query, and update, database designers and database users can now more easily and confidentially model domains that require statement level metadata.  There is a long list of such domains, including domains that model events, domains that require link attributes, sparse matrices, the property graph model, etc.

Bigdata supports RDF* and SPARQL* for the efficient interchange, query, and update of statements about statements.  Today, this is enabled to through the “SIDS” option


This enables the historical mechanism for efficient statements about statements in bigdata.  In the future, we plan to add support for RDF* and SPARQL* to the quads mode of the platform as well.  This will allow statement level metadata to co-exist seamlessly with the named graphs model.


[1] http://arxiv.org/abs/1406.3399

May 302014

Here is a post I just did on the gremlin-users Google Group. Thought it might be of interest to a wider audience as well.



On Thursday, May 29, 2014 12:30:20 PM UTC-6, Jack wrote:

Would you and Marko care to explain the big differentiators between Titan and BigData?



I have never done a comprehensive side-by-side with Titan/Cassandra but I can tell you a little about what Bigdata offers. The genesis for Bigdata was the BigTable paper Google did back in 2006. At that time we were very interested in using graphs and particularly the semantic web to facilitate dynamic federation and semantic alignment of heterogeneous data within a schema flexible framework, all at scale. The landscape for graph databases was quite different back then, and within the semantic web community the real focus was semantics, not scale. Using the principles Google outlined for BigTable, we designed Bigdata from the ground up to be a massively scalable distributed database specifically for graphs.

Bigdata at its core is really a KV store – all data is ultimately persisted inside unsigned byte[] key -> unsigned byte[] value BTree indices. These indices can be key-range sharded and dynamically distributed and load balanced across a cluster. On top of the KV layer, Bigdata has a graph database layer that supports the RDF data model. Graph data is triple indexed to achieve perfect access paths for all eight possible graph access patterns. This concept of covering indices was developed by Andreas Harth and Stefan Decker back in 2005 as part of their YARS database. Using these indices, we can support arbitrary graph pattern joins at the core of our query engine, which supports the high-level query language SPARQL, the only open-standard we have as a community for graph query. In the scale-out mode of the database, the query engine pushes intermediate solutions out across the cluster and executes joins at the data. I think this is probably the key differentiating feature over other graph databases written on top of existing KV stores like Cassandra and Accumulo – these implementations tend to use a client-based query controller (if they provide a query controller at all) that pulls data across the network and does joins at the controller, instead of pushing the computation out to the data. This client-controller strategy can result in a huge amount of wasted IO and network traffic.


Bigdata was designed from the ground up to perform well as both a single-server and distributed database. Bigdata as a single-server database supports up to 50 billion RDF statements (each statement translates roughly to one vertex, edge, or property). Single-server mode comprises several deployment modes as well – you can stand up Bigdata as an actual server and access it via its REST API. There is a BigdataGraphRemote Blueprints implementation that wraps this mode. You can also use Bigdata embedded inside your application’s JVM. There is a BigdataGraphEmbedded Blueprints implementation that wraps this mode.

I suppose the key difference between Titan and Bigdata might be Bigdata’s query optimizer. With a query optimizer you can give the database an operator tree in the form of a declarative query and the query optimizer can do things like use cardinalities of the different operators to determine an optimal execution strategy. Without this all a database can do is exactly what you to tell it to do in exactly the order you tell it to do it, which oftentimes is not the best order at all. This leads to “hand-optimization” to get queries to run quickly (I want to combine these five different predicates to select vertices or edges but I have to re-order them myself to get the best performance). We’ve done a little bit of work exposing the query optimizer in the BigdataGraph implementation – we provide a custom GraphQuery implementation that will let you specify predicates to be executed by the query engine with the help of the query optimizer. We would like to expose other aspects of Bigdata’s query engine/optimizer through Blueprints as well.

I am also not aware of an HA architecture for Titan, but this might be my own ignorance. Bigdata has a high-availability architecture based on a quorum model. In this mode all data is kept on all nodes so queries are answered locally and can be load-balanced to achieve perfect linear scaling for read. Data is replicated using a low-level write replication pipeline with a 2-phase commit. The cluster requires a simple majority quorum to be available. Nodes can go offline temporarily and come back, or new nodes can join in their place. Re-joining or new nodes will catch up to the current state using a playback of the missing commits from the current quorum leader. If the quorum leader goes down this role will failover automatically to another node.


One other interesting feature of Bigdata is an integrated graph analytics engine that supports the Gather-Apply-Scatter (GAS) API. GAS lets you do interesting traversal based analysis – generally operations written on top of BFS or multiple BFS passes. The canonical examples are Page Rank and Shortest Path (SSSP). The GAS engine is integrated directly into Bigdata’s query engine, although this functionality is not yet exposed through the Blueprints API. I’ve spoken with Marko about how this might get exposed in TinkerPop3. In the meantime you can always work with your graph data inside Bigdata through any of the other APIs as well (you are not limited to only Blueprints or only Sesame or only the Bigdata Workbench for a particular database instance).

We also did a literature review of the state of the art in graph database technology about a year ago that might further address your question. There is an entire section on KV stores and Map/Reduce systems.


The Blueprints implementation over Bigdata is very new and we are very excited to get it out into the community and get feedback on it. We welcome comments and suggestions and please do let us know if you find any problems. The best thing to do with an issue is to post it to our trac system, preferably with a small self-contained test case that demonstrates the issue.



Mike Personick
Core Bigdata Development Team

May 282014

We will be presenting on MapGraph on June 22nd at the second annual SIGMOD/GRADES workshop.  While the full paper is not yet published, we have opted to ensure that the MapGraph publication will be available under the ACM open access.

Z. Fu, M. Personick, R. Farber, B. Thompson, “MapGraph: A High Level API for Fast Development of High-Performance Graph Analytics on GPUs”, Proceedings of the Second International Workshop on Graph Data Management Experience and Systems (GRADES 2014), June 22, 2014, Snowbird, Utah, USA.

You can also learn more about MapGraph at the GraphLab workshop (July 21st, 2014) and NoSQL Now (Aug 19-21, San Jose).