arangosh> a1 = db.example.insert({ a : 1 }); { "_id" : "example/15140", "_key" : "15140", "_rev" : "_VOyxnUe---" } arangosh> a2 = db.example.replace(a1, { a : 2 }); { "_id" : "example/15140", "_key" : "15140", "_rev" : "_VOyxnUi---", "_oldRev" : "_VOyxnUe---" } arangosh> a3 = db.example.replace(a1, { a : 3 }); [ArangoError 1200: precondition failed]