GraphDB is a distributed RDF graph database that supports SPARQL queries. It is implemented as a Storage and Inference Layer over the RDF4J framework. It provides cluster support, and uses the TRREE engine for inference and reasoning. It also supports Lucene, Solr, and Elasticsearch connectors for fast aggregation searches.


Ontotext and OWLIM started off within Sirma Group in its R&D division, where OWLIM was first developed. OWLIM comes from "OWL In Memory" since it was originally an in-memory database. Ontotext later spun off into its own business. OWLIM was then later renamed as GraphDB, after Ontotext acquired the rights from sones GraphDB, and is a commercial product.


Virtual Views

GraphDB supports a Graph View interface which takes in SPARQL queries and retrieves data for the user, which is also visually shown.

Query Compilation

Code Generation Stored Procedure Compilation

GraphDB allows users to define custom rulesets, which can be compiled using its internal rule compiler. The rulesets are used to generate java code and are then instantiated. These rulesets are similar to stored procedures.

Storage Model


GraphDB uses an RDF model.

Foreign Keys


Constraints are supported by GraphDB. In particular, integrity constraints are supported.

System Architecture


Every worker node has a copy of the repository, and updates are tried on one worker node and then propagated by the master to the other worker nodes. The master checks for synchronization between the worker nodes.

Query Interface


RDF4J supports SPARQL and SeRQL for RDF queries, and thus GraphDB supports these as well, since GraphDB is built on top of RDF4J.


Hash Table Patricia/Radix Trie

GraphDB supports several optional indices: predicate lists (subject-predicate and object-predicate), context indices, and literal indices, each optimized for different kinds of queries. These are implemented with hash tables. The GeoSPARQL plugin for GraphDB , which is used for geo-spatial data representation and querying, supports the quad prefix tree and geohash prefix tree for indexing.

Stored Procedures


GraphDB supports rulesets that are stored as .pie files and can be compiled and instantiated. These rulesets are similar to stored procedures and are used for inference.

Data Model

Triplestore / RDF

GraphDB uses an RDF data model. The RDF data model describes the meaning of information and their relationships using triples. A triple is of the format subject-predicate-object and is a unique identifier.

Concurrency Control

Timestamp Ordering

GraphDB supports transactions. GraphDB supports Timestamp Ordering Concurrency Control, where each transaction is given a timestamp and is queued based on its timestamp. Additionally, updating transactions do not block readers.

Isolation Levels

Read Committed

GraphDB supports the read committed isolation level, where an update is only visible to other users when it has been committed.


Hash Join

GraphDB supports joins. RDF4J supports hash joins, and since GraphDB is implemented using the SAIL API over RDF4J, GraphDB uses RDF4J's query engines, and thus also supports hash joins.

Storage Architecture


GraphDB supports a disk-oriented storage architecture, where all of the data is stored in disk files.


Dictionary Encoding

GraphDB uses Snappy to compress all masters and workers for replications. Snappy is a compresson/decompression library written by Google and uses a LZ77-type compression algorithm, which is a dictionary encoder.

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Tech Docs



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Compatible With

Elasticsearch, Sesame, Solr

Operating Systems

All OS with Java VM