Database Reference
In-Depth Information
Sharding
In this chapter
Sharding concepts
Setting up and loading a sample shard cluster
Administration and failover
MongoDB was designed from the start to support sharding. This has always been an
ambitious goal because building a system that supports automatic range-based par-
titioning and balancing, with no single point of failure, is hard. Thus the initial sup-
port for production-level sharding was first made available in August 2010 with the
release of MongoDB v1.6. Since then, numerous improvements have been made to
the sharding subsystem. Sharding effectively enables users to keep large volumes of
data evenly distributed across nodes and to add capacity as needed. In this chapter,
I'll present the layer that makes this possible in all its glory.
We'll begin with a sharding overview, discussing what sharding is, why it's impor-
tant, and how it's implemented in MongoDB. Although this will give you a basic
working knowledge of sharding, you won't fully understand it until you set up your
own sharded cluster. That's what you'll do in the second section, where you'll build
a sample cluster to host data from a massive Google Docs-like application. We'll
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