Relationships
Dgraph stores relationships among entities to represent graph structures, and also stores literal properties of entities.
This makes it easy for Dgraph to ingest the RDF N-Quad format, where each line represents
Node, RelationName, Node, LabelorNode, RelationName, ValueLiteral, Label
The first represents relations among entities (nodes in graph terminology) and the second represents the relationship of a Node to all it’s named attributes.
Often, the optional Label is omitted, and therefore the N-Quad data is also referred to as “triples.” When it is included, it represents which Tenant or Namespace the data lives in within Dgraph.
In our product (the code or the GUI, and also in older documentation) you may see other terminology such as
Edge instead of Relationship Predicate instead of Relationship Entity or Vertex instead of Node
Similarly in the RDF spec you’ll see Subject and Object instead of Node Predicate instead of Relationship.
This is unavoidable, since graph databases, RDF, and graph theory have separate origins that do not all share terminology.
Dgraph can automatically generate a reverse relation. If the user wants to run queries in that direction, they would need to define the reverse relationship
For Relationships, the subject and object are represented as 64-bit numeric UIDs and the relationship name itself links them:
For literal attributes of a Node, the subject must still (and always) be a numeric UID, but the Object will be a primitive value. These can be thought of as