Query Interface

Gremlin

JanusGraph uses Gremlin graph query language to retrieve data from and modify data in the graph. Gremlin is a functional language whereby traversal operators are chained together to form path-like expressions, expressing query or data modification on graphs.

A Gremlin query is a chain of operations/functions that are evaluated from left to right. A simple example of gremlin language to query the name of Alex's grandson on his genealogy graph is provided below

g.V().has('name', 'Alex').out('father').out('father').values('name')

The query can be read as g: for the current graph V: for the vertices in the graph has('name', 'Alex'): filters the vertices down to those with the "name" property "Alex" out('father'): traverse outgoing through edges whose type is "father" from "Alex" (Notice here the result can be more than one vertices) out('father'): traverse outgoing through edges whose type is "father" from "Alex"' son (the result from the last traversal) values('name'): get the property of "name"

Data Model

Graph