Introduction
The Neo4j Graph Data Science (GDS) library provides efficiently implemented, parallel versions of common graph algorithms, exposed as Cypher procedures. Additionally, GDS includes machine learning pipelines to train predictive supervised models to solve graph problems, such as predicting missing relationships.
1. API tiers
The GDS API comprises Cypher procedures and functions. Each of these exist in one of three tiers of maturity:
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Production-quality
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Indicates that the feature has been tested with regards to stability and scalability.
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Features in this tier are prefixed with
gds.<operation>
.
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Beta
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Indicates that the feature is a candidate for the production-quality tier.
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Features in this tier are prefixed with
gds.beta.<operation>
.
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Alpha
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Indicates that the feature is experimental and might be changed or removed at any time.
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Features in this tier are prefixed with
gds.alpha.<operation>
.
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The Operations Reference, lists all operations in GDS according to their tier.
2. Algorithms
Graph algorithms are used to compute metrics for graphs, nodes, or relationships.
They can provide insights on relevant entities in the graph (centralities, ranking), or inherent structures like communities (community-detection, graph-partitioning, clustering).
Many graph algorithms are iterative approaches that frequently traverse the graph for the computation using random walks, breadth-first or depth-first searches, or pattern matching.
Due to the exponential growth of possible paths with increasing distance, many of the approaches also have high algorithmic complexity.
Fortunately, optimized algorithms exist that utilize certain structures of the graph, memoize already explored parts, and parallelize operations. Whenever possible, we’ve applied these optimizations.
The Neo4j Graph Data Science library contains a large number of algorithms, which are detailed in the Algorithms chapter.
2.1. Algorithm traits
Algorithms in GDS have specific ways to make use of various aspects of its input graph(s). We call these algorithm traits. When an algorithm supports an algorithm trait this indicates that the algorithm has been implemented to produce well-defined results in accordance with the trait. The following algorithm traits exist:
- Directed
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The algorithm is well-defined on a directed graph.
- Undirected
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The algorithm is well-defined on an undirected graph.
- Homogeneous
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The algorithm will treat all nodes and relationships in its input graph(s) similarly, as if they were all of the same type. If multiple types of nodes or relationships exist in the graph, this must be taken into account when analysing the results of the algorithm.
- Heterogeneous
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The algorithm has the ability to distinguish between nodes and/or relationships of different types.
- Weighted
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The algorithm supports configuration to set node and/or relationship properties to use as weights. These values can represent cost, time, capacity or some other domain-specific properties, specified via the nodeWeightProperty, nodeProperties and relationshipWeightProperty configuration parameters. The algorithm will by default consider each node and/or relationship as equally important.
3. Graph Catalog
In order to run the algorithms as efficiently as possible, GDS uses a specialized graph format to represent the graph data. It is therefore necessary to load the graph data from the Neo4j database into an in memory graph catalog. The amount of data loaded can be controlled by so called graph projections, which also allow, for example, filtering on node labels and relationship types, among other options.
For more information see Graph Management.
4. Editions
The Neo4j Graph Data Science library is available in two editions.
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The open source Community Edition:
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Includes all algorithms.
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Most of the catalog operations to manage graphs, models and pipelines are available. Unavailable operations are listed below.
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Limits the concurrency to 4 CPU cores.
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Limits the capacity of the model catalog to 4 models.
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The Neo4j Graph Data Science library Enterprise Edition:
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Can run on an unlimited amount of CPU cores.
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Supports the role-based access control system (RBAC) from Neo4j Enterprise Edition.
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Support running GDS as part of a Neo4j cluster deployment.
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Includes capacity and load monitoring.
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Supports various additional graph catalog features, including:
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Graph backup and restore.
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Data import and export via Apache Arrow.
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Supports various additional model catalog features, including:
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Storing unlimited amounts of models in the model catalog.
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Sharing of models between users, by publishing it.
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Model persistence to disk.
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Supports an optimized graph implementation.
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Allows the configuration of defaults and limits.
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For more information see System Requirements - CPU.
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