Posts Tagged → Mongo

MongoDB – Part 6 – GridFS

If you could have a wild guess at what GridFS is used for, you’d probably say some kind of file system and you wouldn’t be completely wrong. On the contrary, GridFS isn’t actually a filesystem, but rather a convention for storing large binary data files inside MongoDB.

I haven’t covered storing binary data in MongoDB yet, however it’s possible to store binary data in standard documents, without using GridFS at all. This is possible using the BSON type BinData. It’s not very well supported by the mongo client, however most language drivers have good support, just google “MongoDB BinData”. This is all well and good, in fact if you’re storing under 16MB of data per file, it’s recommended to use this approach. If however you are storing binary files larger than 16MB, GridFS is the way to go. 16MB is the maximum size of a document in MongoDB.

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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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