Java Shell
Switch branches/tags
Nothing to show
Latest commit 6cbacb3 Jun 23, 2017 @Venom590 Venom590 committed with s1ck [#573] Add Neighborhood Methods
* this adds reduceOnEdges and reduceOnNeighbors methods to LogicalGraph being able to perform custom aggreagtion logic on incident edges / adjacent vertices and returning an updated LogicalGraph
* fixes #573

Build Status

Gradoop: Distributed Graph Analytics on Hadoop

Gradoop is an open source (GPLv3) research framework for scalable graph analytics built on top of Apache Flink™ and Apache HBase™. It offers a graph data model which extends the widespread property graph model by the concept of logical graphs and further provides operators that can be applied on single logical graphs and collections of logical graphs. The combination of these operators allows the flexible, declarative definition of graph analytical workflows. Gradoop can be easily integrated in a workflow which already uses Flink™ operators and Flink™ libraries (i.e. Gelly, ML and Table).

Gradoop is work in progress which means APIs may change. It is currently used as a proof of concept implementation and far from production ready.

Further Information (articles and talks)

Data Model

In the extended property graph model (EPGM), a database consists of multiple property graphs which are called logical graphs. These graphs describe application-specific subsets of vertices and edges, i.e. a vertex or an edge can be contained in multiple logical graphs. Additionally, not only vertices and edges but also logical graphs have a type label and can have different properties.

Data Model elements (logical graphs, vertices and edges) have a unique identifier, a single label (e.g. User) and a number of key-value properties (e.g. name = Alice). There is no schema involved, meaning each element can have an arbitrary number of properties even if they have the same label.

Graph operators

The EPGM provides operators for both single logical graphs as well as collections of logical graphs; operators may also return single graphs or graph collections. The following tables contains an overview (GC = Graph Collection, G = Logical Graph).

Unary logical graph operators (one graph as input):

Operator Output Output description Impl
Aggregation G Graph with result of an aggregate function as a new property Yes
Matching GC Graphs that match a given graph pattern Yes
Transformation G Graph with transformed (graph, vertex, edge) data Yes
Grouping G Structural condense of the input graph Yes
Subgraph G Subgraph that fulfils given vertex and edge predicates Yes

Binary logical graph operators (two graphs as input):

Operator Output Output description Impl
Combination G Graph with vertices and edges from both input graphs Yes
Overlap G Graph with vertices and edges that exist in both input graphs Yes
Exclusion G Graph with vertices and edges that exist only in the first graph Yes
Equality {true, false} Compare graphs in terms of identity or equality of contained elements Yes
VertexFusion G The second graph is fused to a single vertex within the first graph Yes

Unary graph collection operators (one collection as input):

Operator Output Output description Impl
Matching GC Graphs that match a given graph pattern Yes
Selection GC Filter graphs based on their attached data (i.e. label, properties) Yes
Distinct GC Collection with no duplicate graphs Yes
SortBy GC Collection sorted by values of a given property key No
Limit GC The first n arbitrary elements of the input collection Yes

Binary graph collection operators (two collections as input):

Operator Output Output description Impl
Union GC All graphs from both input collections Yes
Intersection GC Only graphs that exist in both collections Yes
Difference GC Only graphs that exist only in the first collection Yes
Equality {true, false} Compare collections in terms of identity or equality of contained elements Yes

Auxiliary operators:

Operator In Out Output description Impl
Apply GC GC Applies unary operator (e.g. aggregate) on each graph in the collection Yes
Reduce GC G Reduces collection to single graph using binary operator (e.g. combine) Yes
Call GC/G GC/G Applies external algorithm on graph or graph collection Yes


Use gradoop via Maven

  • Add repository and dependency to your maven project
    <name>Database Group Leipzig University</name>


Build gradoop from source

Gradoop modules


The main contents of that module are the EPGM data model and a corresponding POJO implementation which is used in Flink™. The persistent representation of the EPGM is also contained in gradoop-common and together with its mapping to HBase™.


Input and output formats for reading and writing graph collections from Apache HBase.


This module contains reference implementations of the EPGM operators. The EPGM is mapped to Flink™ DataSets while the operators are implemented using DataSet transformations. The module also contains implementations of general graph algorithms (e.g. Label Propagation, Frequent Subgraph Mining) adapted to be used with the EPGM model.


Contains example pipelines showing use cases for Gradoop.

  • Graph grouping example (build structural aggregates of property graphs)
  • Social network examples (composition of multiple operators to analyze social networks graphs)
  • Input/Output examples (usage of DataSource and DataSink implementations)
  • Benchmarks used for cluster evaluations


Used to maintain the code style for the whole project.

Version History

  • 0.0.1 first prototype using Hadoop MapReduce and Apache Giraph for operator processing
  • 0.0.2 support for HBase as distributed graph storage
  • 0.0.3 Apache Flink replaces MapReduce and Giraph as operator implementation layer and distributed execution engine
  • 0.1 Major refactoring of internal EPGM representation (e.g. ID and property handling), Equality Operators, GDL-based unit testing
  • 0.2.0 Pattern Matching and Frequent Subgraph Mining algorithms


Apache®, Apache Flink™, Flink™, Apache HBase™ and HBase™ are either registered trademarks or trademarks of the Apache Software Foundation in the United States and/or other countries.