MongoDB: The Definitive Guide

Chapter 3. Creating, Updating, and Deleting Documents

This chapter covers the basics of moving data into and out of the database, including the following:

• Adding new documents to a collection

• Removing documents from a collection

• Updating existing documents

• Choosing the correct level of safety versus speed for all of these operations

Inserting and Saving Documents

Inserts are the basic method for adding data to MongoDB. To insert a document into a collection, use the collection’s insert method:

> db.foo.insert({"bar" : "baz"})

This will add an "_id" key to the document (if one does not already exist) and save it to MongoDB.

Batch Insert

If you have a situation where you are inserting multiple documents into a collection, you can make the insert faster by using batch inserts. Batch inserts allow you to pass an array of documents to the database.

Sending dozens, hundreds, or even thousands of documents at a time can make inserts significantly faster. A batch insert is a single TCP request, meaning that you do not incur the overhead of doing hundreds of individual requests. It can also cut insert time by eliminating a lot of the header processing that gets done for each message. When an individual document is sent to the database, it is prefixed by a header that tells the database to do an insert operation on a certain collection. By using batch insert, the database doesn’t need to reprocess this information for each document.

Batch inserts are intended to be used in applications, such as for inserting ...