Is there a limit to the number of Labels?

If so, what are the performance considerations of having billions of labels?

Labels do you mean using Predicates as labels?
If so, nope, you just gonna have a huge schema to deal with.

Sorry, I’m coming from Neo4j where they have a labeled-property graph db:

Is that what Predicates are?

Dgraph doesn’t have the concept of Labels as Neo4j has. We have predicates, which are the smallest part of an object/node. You can have kind of “labels” by using an empty predicate. But in Dgraph we recommend that you use Types instead.

A triple consist of Identifier + Predicate + Value or Objetc.