title: Is it better to save id of a document in another document as ObjectId or String
body: <p>Lets take a simple "bad" example : lets assume I have 2 collections 'person' and 'address'. And lets assume in 'address' I want to store '_id' of the person the address is associated with. Is there any benefit to store this "referential key" item as ObjectId vs string in 'address' collection?</p>
  
  <p>I feel like storing them as string should not hurt but I have not worked in mongo for very long and do not know if it will hurt down the road if I follow this pattern. </p>
  
  <p>I read the post here : <a href="https://stackoverflow.com/questions/7764781/store-id-as-object-or-string-in-mongodb">Store _Id as object or string in MongoDB?</a>
  And its said that ObjectId is faster, and I assume its true if you are fetching/updating using the ObjectId in parent collection(for eg. fetching/updating 'person' collection using person._id as ObjectId), but I couldn't find anything that suggests that same could be true if searching by string id representation in other collection(in our example search in address collection by person._id as string)</p>
  
  <p>Your feedback is much appreciated.</p>