arangosh> a1 = db.example.insert({ a : 1 }); { "_id" : "example/17318", "_key" : "17318", "_rev" : "_Vsb0ZVm---" } arangosh> a2 = db._replace(a1, { a : 2 }); { "_id" : "example/17318", "_key" : "17318", "_rev" : "_Vsb0ZVm--A", "_oldRev" : "_Vsb0ZVm---" } arangosh> a3 = db._replace(a1, { a : 3 }); [ArangoError 1200: precondition failed]