The _id field is a field that it is populated as ObjectId or a unique value that we, as database administrator, asign to each document in a collection.
I have some doubts about this field:
- If we use another field name as a collection key, could we simply delete it? I think no, because in the course says that this field always must exists.
- If we, as admin, use a unique value but that it not the type object id, it will affect the sharding or maybe anything in the replication of nodes?
- How could we define a key field that is not _id?