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


documents size to large,
index key not granular enough, and/or 
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" }

min: { Country:"FR", City:"Paris" } max: { Country:"US": City:"New York" }


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 


get the chunkID with the query 


  db.coll.find({ Country:"US", City:"LA" })
  get all the docs within this chunk?
  
  Other suggestions are welcome.
  Thanks in advance
use config show collections
  
  db.chunks.findOne()
  
  use config db.settings.save({_id: "chunksize", value: 2})
  
  sh.status()