Edges in a property graph

An edge, in a property graph, connects two vertices, and has:

  • A set of named properties.
  • A source vertex (aka out vertex).
  • A destination vertex (aka in vertex).

Note: Pacer edges are directed, but we can always simulate an undirected graph by traversing edges in both (incoming and outgoing) directions.

Let's see the basic edge operations in Pacer ...

Creating edges

Edges are created by calling the add_edges_to method on a vertex.


You can delete an edge from the graph by calling its delete! method.
Note: Like all methods that modify the graph, this methods must be called inside a transaction.

Getting vertices

We use Blueprints terminology, and say that an edge goes from its out vertex into its in vertex.
That is, out_vertex --edge--> in_vertex.


Get the source vertex.


Get the destination vertex.


Get both vertices.

Note: All the methods above return a route (i.e. A collection) of vertices. In the case of out_v and in_v the route contains a single vertex.


Getting/setting edge properties works the same way as getting/setting vertex properties.


The properties methods is used for getting all properties, as a hash object.


The [] operator is used for getting and setting a specific property.