MongoDB in Action, Second Edition

Chapter 7. Updates, atomic operations, and deletes

This chapter covers

• Updating documents
• Processing documents atomically
• Applying complex updates to a real-world example
• Using update operators
• Deleting documents

To update is to write to existing documents. Doing this effectively requires a thorough understanding of the kinds of document structures available and of the query expressions made possible by MongoDB. Having studied the e-commerce data model in the last two chapters, you should have a good sense of the ways in which schemas are designed and queried. We’ll use all of this knowledge in our study of updates.

Specifically, we’ll look more closely at why we model the category hierarchy in such a denormalized way, and how MongoDB’s ...