Mongo DB链式查询

Question

I am new to MongoDB and as I wonder if a chained query like the following is possible(somewhat like a join):

db.places.insert({
"_id": original_id
"place_name": "Broadway Center"
"url": "bc.example.net"})

db.people.insert({
"name": "Erin"
"places_id": original_id
"url":  "bc.example.net/Erin"})

So given a place name string, I want to select the people associated with that place. But the people collection only reference the place id, not the place name.

Answer 1

You cannot use joins in MongoDB.

The idiomatic solution is retrieve all place_ids for that place_name from your places collection and then use the place_ids to query in your people collection.

Another option is keeping, for example, places in people collection (this makes more sense to me than people inside places collection but, of course, it depends on your domain). But then you have to take into account that in case that only one place changes, you have to change all people documents sharing a specific place. If people and places are in separate collections this doesn't happen so it depends on if we have static data or not and on if we want to optimize searches or updates.