arangosh> db.examples.ensureCapConstraint(10);
{ 
  "id" : "examples/1124987787", 
  "type" : "cap", 
  "size" : 10, 
  "byteSize" : 0, 
  "unique" : false, 
  "isNewlyCreated" : true, 
  "code" : 201 
}
arangosh> for (var i = 0;  i < 20;  ++i) { var d = db.examples.save( { n : i } ); }
arangosh> db.examples.count();
10