arangosh> a1 = db.example.insert({ a : 1 }); { "_id" : "example/73610", "_key" : "73610", "_rev" : "_ZG8LmVa--A" } arangosh> a2 = db.example.replace(a1, { a : 2 }); { "_id" : "example/73610", "_key" : "73610", "_rev" : "_ZG8LmVe--_", "_oldRev" : "_ZG8LmVa--A" } arangosh> a3 = db.example.replace(a1, { a : 3 }); [ArangoError 1200: precondition failed]