MongoDB: The Definitive Guide, 2nd Edition

Chapter 13. Introduction to Sharding

This chapter covers how to scale with MongoDB:

• What sharding is and the components of a cluster

• How to configure sharding

• The basics of how sharding interacts with your application

Introduction to Sharding

Sharding refers to the process of splitting data up across machines; the term partitioning is also sometimes used to describe this concept. By putting a subset of data on each machine, it becomes possible to store more data and handle more load without requiring larger or more powerful machines, just a larger quantity of less-powerful machines.

Manual sharding can be done with almost any database software. Manual sharding is when an application maintains connections to several different database servers, each of which are completely independent. The application manages storing different data on different servers and querying against the appropriate server to get data back. This approach can work well but becomes difficult to maintain when adding or removing nodes from the cluster or in the face of changing data distributions or load patterns.

MongoDB supports autosharding, which tries to both abstract the architecture away from the application and simplify the administration of such a system. MongoDB allows your application to ignore the fact that it isn’t talking to a standalone MongoDB server, to some extent. On the operations side, MongoDB automates balancing data across shards and makes it easier to add and remove capacity.

Sharding is the most ...