Taking backup of a small subset of documents in a collection

In the previous recipe, we saw how to backup certain databases and their collections. In this recipe, we will look at how to use the mongodump utility to backup specific documents within a collection.

Getting ready

You need a single node MongoDB installation, preferably with some data in it. Refer to the recipe Creating an index in Chapter 2, Understanding and Managing Indexes, on how to import sample data into a MongoDB instance.

How to do it...

1. Open the mongo shell and check all documents for a specific language:

use mydb

db.mockdata.count({language:"Thai"})

2. You should see the following output:

892

3. Add the following to query.json:

{language: 'Thai'}

4. Execute the mongodump utility with a specific query:

mongodump -d mydb -c mockdata --queryFile query.json

5. You should see the following output:

2017-10-04T12:17:28.559+0000 writing mydb.mockdata
2017-10-04T12:17:28.596+0000 done dumping mydb.mockdata (892 documents)

How it works...

By now, these...