MongoDB – Part 5 – Sharding

Sharding, the art of scalability. That’s a bold statement, after all, there are two very important arts to scalability. What shards allow you to do however, is to scale out. What this means is, you no longer need to keep all of your data on one hard drive or machine, heck not even in the same warehouse or continent. You can have unlimited machines in unlimited geographic locations, connected together and serving data as if it was all the data was stored in one central location.

If you’re not already familiar with the terms scaling up/vertically and scaling out/horizontally, carry on reading. Otherwise you can skip the next few paragraphs.

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MongoDB – Part 4 – Replication

CAP, the theorem behind MongoDB and most NoSQL databases, states that no distributed system can provide consistency, availability and partition tolerance. In this article I’m going to be writing about what MongoDB offers in the replication sector and how you can utilise replication to customise all aspects of the CAP theorem.

I’ll be covering: how to create replication sets, how replication works in MongoDB, how to configure individual nodes in a set, how to retrieve the status of nodes, how to configure write concern when executing queries and common CAP configurations.

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MongoDB – Part 3 – Indexes

It has been a while since my last post on MongoDB, but I’m back and looking to finish off this series over the next 6-8 weeks (Edit: 6-8 months). Anyway, in this article I’m going to be covering all of the different types of indexes you can use in MongoDB

Most of these you’ll have heard of before, providing you’ve used almost any other DBMS. I’ll be providing examples of how to create each index, when you would want to use them and at the end I’ll throw together a few must know tips.

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MongoDB – Part 2 – Databases

OK. So in part 1 we covered a bunch of MongoDB basics. In this part, I plan on covering in detail the core MongoDB databases, what collections they have and what they’re used for.

When you first install MongoDB, two databases are created for you called admin and local. They don’t contain many collections and may not even contain any to begin with, however don’t worry about this, Mongo will create them as an when it needs them.

The third core database is called config. Config databases are a little more complicated, in that they can only be accessed when connected to a shard instead of a particular daemon. I haven’t covered shards yet. But for now just think of shards as individual mongod nodes, that all together form your data set. How this happens is very customisable, these customisable setting are stored in the config database. I’ll cover shards in great detail in a separate post.

Edit: Learn about MongoDB shards

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