How to get all documents from a particular chunks in MongoDB?

From mongos log, I got the following message

 balancer move failed: { chunkTooBig: true, estimatedChunkSize: 408839903, ok: 0.0, errmsg: "chunk too big to move" } from: shard4 to: shard1 

I know this issue occurs due to either

1. documents size to large,


2. index key not granular enough, and/or


3. chunkSize too small

While I'm confident that case 2 and 3 are not the cause, I want to see whether someone abuses the database by inserting extra large documents.

The mongos log shows the docs are in the range :

 min: { Country:"US", City:"LA" } max: { Country:"US": City:"NY" }

I want to aggregate the schema of documents within this range, and see if some documents contain extra fields.

Since the indexes are not monotonically increasing, I can't get all documents within this range (or can i?).

How can I

1. get the chunkID with the query
   

   
   

   db.coll.find({ Country:"US", City:"LA" })

   
   

   
   


2. get all the docs within this chunk?

Other suggestions are welcome. Thanks in advance