Changing the Graph

add_v(), add_e(), property(), drop(), remove_property() and the upsert steps merge_v()/merge_e() write to the graph. Whatever writes, the same guarantees hold:

• One traversal is one unit. It commits when it succeeds; when any step fails (a schema violation, a limit, a timeout) nothing it wrote stays. A whole script, or several traversals in Rust, can be one unit too.
• A schema is enforced on every write, when the graph has one in mode open or closed.
• Writes need permission when the host restricts queries: Create, Update or Delete on the data, checked before the traversal runs.

g.add_v("person").property("name", "ann").as("a")
  .v().has("name", "marko").add_e("knows").to("a")
  .iterate();
g.merge_v(#{name: "ann"}).iterate();                // finds ann, creates nothing
g.v().has("name", "ann").remove_property("age").iterate();