Let's say I have a mongodb collection named customer where each record has this structure :

{ "_id" : 1, "name" : "Joe Smith", "addresses" : [

{ "address1" : "123 Rd", "city" : "LA"}

]}

Let's also save I have a file of newline separated JSON's with the following structure:

{ "_id" : 1, "addresses" : [

{"address1" : "123 Another Street", "city" : "LA"}

] }

After a mongoimport --merge, I'd like the first record to become:

{ "_id" : 1, "name" : "Joe Smith", "addresses" : [

{"address1" : "123 Another Street", "city" : "LA"}

] }

In other words, name field is left untouched because not mentioned in the update, while addresses field is entirely replaced.

The current behavior when using the --upsert option is to replace the entire record (in this example eliminating the name field entirely).