What is a graph database?

NoSQL Concepts

Miriam Antona

Software engineer

Graph databases - overview

• Treat data and its relationships with the same importance
• Based on graph theory
  • branch of mathematics
  • studies graphs for modeling the relationships between objects

Graph databases - parts of a graph

• Vertices/nodes
• Edges

Graph databases - parts of a graph

• Vertices/nodes
• Edges/links/arcs

Graph databases - nodes

• Represent entities (users, cities, airports, employees...)
• Have properties

Graph databases - nodes

• Represent entities (users, cities, airports, employees...)
• Have properties

Graph databases - edges

• Connect the nodes
• Define the relationships between the nodes

Graph databases - edges

• Connect the nodes
• Define the relationships between the nodes

Graph databases - edges

• Connect the nodes
• Define the relationships between the nodes

Graph databases - types of edges

• Directed:
  • Specific direction

Graph databases - types of edges

• Undirected:
  • No direction
  • The relationship is mutual

Graph databases - queries

• Traversing the graph
• Examples:
  • Get all the users that Ben follows
  • Get when Carol started following Shui
  • Get the shortest path from one city to another
• Path: set of nodes and edges across a graph
• Query languages: Cypher, Gremlin, etc.

Popular graph databases

Let's practice!

NoSQL Concepts