What Is a Graph Database? - Amazon Neptune

What Is a Graph Database?

Graph databases like Amazon Neptune are purpose-built to store and navigate relationships. Graph databases have advantages over relational databases for certain use cases—including social networking, recommendation engines, and fraud detection—when you want to create relationships between data and quickly query these relationships. There are a number of challenges to building these types of applications using a relational database. It requires you to have multiple tables with multiple foreign keys. The SQL queries to navigate this data require nested queries and complex joins that quickly become unwieldy. And the queries don't perform well as your data size grows over time.

Neptune uses graph structures such as nodes (data entities), edges (relationships), and properties to represent and store data. The relationships are stored as first-order citizens of the data model. This condition allows data in nodes to be directly linked, dramatically improving the performance of queries that navigate relationships in the data. The interactive performance at scale in Neptune effectively enables a broad set of graph use cases.

A graph in a graph database can be traversed along specific edge types, or across the entire graph.

Graph databases can represent how entities relate by using actions, ownership, parentage, and so on. Whenever connections or relationships between entities are at the core of the data that you're trying to model, a graph database is a natural choice. Therefore, graph databases are useful for modeling and querying social networks, business relationships, dependencies, shipping movements, and similar items.

You can use edges to show typed relationships between entities (also called vertices or nodes). Edges can describe parent-child relationships, actions, product recommendations, purchases, and so on. A relationship, or edge, is a connection between two vertices that always has a start node, end node, type, and direction.

An example of a common use case that is suited to a graph is social networking data. Amazon Neptune can quickly and easily process large sets of user profiles and interactions to build social networking applications. Neptune enables highly interactive graph queries with high throughput to bring social features into your applications. For example, suppose that you want to build a social feed into your application. You can use Neptune to provide results that prioritize showing your users the latest updates from their family, from friends whose updates they "Like," and from friends who live close to them.

Following is an example of a social network graph.

            Diagram showing the relationships among people and hobbies in a social

This example models a group of friends and their hobbies as a graph. A simple traversal of this graph can tell you what Justin's friends like.

Graph Database Uses

Graph databases are useful for connected, contextual, relationship-driven data. An example is modeling social media data, as shown in the previous section. Other examples include recommendation engines, driving directions (route finding), logistics, diagnostics, and scientific data analysis in fields like neuroscience.

Fraud Detection

Another use case for graph databases is detecting fraud. For example, you can track credit card purchases and purchase locations to detect uncharacteristic use. Detecting fraudulent accounts is another example.

With Amazon Neptune, you can use relationships to process financial and purchase transactions in near-real time to easily detect fraud patterns. Neptune provides a fully managed service to execute fast graph queries to detect that a potential purchaser is using the same email address and credit card as a known fraud case. If you are building a retail fraud detection application, Neptune can help you build graph queries. These queries can help you easily detect relationship patterns, such as multiple people associated with a personal email address or multiple people who share the same IP address but reside in different physical addresses.

The following graph shows the relationship of three people and their identity-related information. Each person has an address, a bank account, and a social security number. However, we can see that Matt and Justin share the same social security number, which is irregular and indicates possible fraud by one or more of the connected people. A query to the graph database could help you discover these types of connections so that they can be reviewed.

                Diagram showing the relationships among people and their personal

Recommendation Engines

With Amazon Neptune, you can store relationships between information categories such as customer interests, friends, and purchase history in a graph. You can then quickly query it to make recommendations that are personalized and relevant. For example, you can use a highly available graph database to make product recommendations to a user based on which products are purchased by others who follow the same sport and have similar purchase history. Or, you can identify people who have a friend in common, but don’t yet know each other, and make a friendship recommendation.

Knowledge Graphs

Amazon Neptune helps you build knowledge graph applications. A knowledge graph lets you store information in a graph model and use graph queries to help your users navigate highly connected datasets more easily. Neptune supports open source and open standard APIs so that you can quickly use existing information resources to build your knowledge graphs and host them on a fully managed service. For example, suppose that a user is interested in the Mona Lisa by Leonardo da Vinci. You can help this user discover other works of art by the same artist or other works located in The Louvre. Using a knowledge graph, you can add topical information to product catalogs, build and query complex models of regulatory rules, or model general information, like Wikidata.

Life Sciences

Amazon Neptune helps you build applications that store and navigate information in the life sciences, and process sensitive data easily using encryption at rest. For example, you can use Neptune to store models of disease and gene interactions. You can search for graph patterns within protein pathways to find other genes that might be associated with a disease. You can model chemical compounds as a graph and query for patterns in molecular structures. Neptune helps you integrate information to tackle challenges in healthcare and life sciences research. You can use Neptune to create and store patient relationships from medical records across different systems. You can topically organize research publications to find relevant information quickly.

Network / IT Operations

You can use Amazon Neptune to store a graph of your network. You can then use graph queries to answer questions like how many hosts are running a specific application. Neptune can store and process billions of events to manage and secure your network. If you detect an event, you can use Neptune to quickly understand how it might affect your network by querying for a graph pattern using the attributes of the event. You can issue graph queries to Neptune to find other hosts or devices that may be compromised. For example, if you detect a malicious file on a host, Neptune can help you find the connections between the hosts that spread the malicious file. It can help you trace it to the original host that downloaded it.

Graph Queries and Traversals

Neptune supports two different graph query languages: Gremlin (Apache TinkerPop3) and SPARQL (SPARQL 1.1).

  • Gremlin is a graph traversal language and, as such, a query in Gremlin is a traversal made up of discrete steps. Each step follows an edge to a node.

  • SPARQL is a declarative query language based on graph pattern-matching standardized by the W3C.

Given the following graph of people (nodes) and their relationships (edges), you can find out who the "friends of friends" of a particular person are—for example, the friends of Howard's friends.

                Diagram showing relationships among people including their

Looking at the graph, you can see that Howard has one friend, Jack, and Jack has four friends: Annie, Harry, Doug, and Mac. This is a simple example with a simple graph, but these types of queries can scale in complexity, dataset size, and result size.

The following is a Gremlin traversal query that returns the names of the friends of Howard's friends.

g.V().has('name', 'Howard').out('friend').out('friend').values('name')

The following is a SPARQL query that returns the names of the friends of Howard's friends.


Each part of any Resource Description Framework (RDF) triple has a URI associated with it. In this example, the URI prefix is intentionally short. For more information, see Accessing the Neptune graph with SPARQL.

prefix : <#> select ?names where { ?howard :name "Howard" . ?howard :friend/:friend/:name ?names . }

For more examples of Gremlin queries, see Accessing the Neptune Graph with Gremlin.

For more examples of SPARQL queries, see Accessing the Neptune graph with SPARQL.

To learn about using Amazon Neptune, we recommend that you start with the following sections: