Introduction to MongoDB - MongoDB Basics - page 17

The MongoDB Aggregation Framework
MapReduce is a very powerful tool, but it has one major drawback; it's not exactly easy to
use. Many database systems are used for reporting, and SQL databases in particular make
this very easy. If you want to group results or find the maximum and average, then it's very
simple to express that idea and get the result you're looking for. Unfortunately, it's not
quite so simple to do that in MapReduce, and you effectively have to do all the wiring up
yourself. This can often mean that an otherwise simple task is unnecessary challenging.
In response to this, MongoDB Inc (previously 10gen) added the aggregation
framework. It is pipeline-based, similar to piping commands in Linux shells and allows
you to take individual pieces of a query and string them together in order to get the result
you're looking for. This maintains the benefits of MongoDB's document oriented design
while still providing high performance.
So if you need all the power of MapReduce, you still have it at your beck and call. If
you just want to do some basic statistics and number crunching, you're going to love the
new aggregation framework. You'll learn more about the aggregation framework and its
commands in Chapters 4 and 6.
Getting Help
MongoDB has a great community, and the core developers are very active and easily
approachable, and they typically go to great lengths to help other members of the
community. MongoDB is easy to use and comes with great documentation; however, it's
still nice to know that you're not alone, and help is available, should you need it.
Visiting the Website
The first place to look for updated information or help is on the MongoDB website
( www://mongodb.org ) . This site is updated regularly and contains all the latest MongoDB
goodness. On this site, you can find drivers, tutorials, examples, frequently asked
questions, and much more.
Chatting with the MongoDB Developers
The MongoDB developers hang out on Internet Relay Chat (IRC) at #MongoDB on the
Freenode network ( www.freenode.net ). MongoDB's developers are based in New York,
but they are often found chatting in this channel well into the night. Of course, the
developers do need to sleep at some point (coffee only works for so long!); fortunately,
there are also many knowledgeable MongoDB users from around the world who are
ready to help out. Many people who visit the #MongoDB channel aren't experts; however,
the general atmosphere is so friendly that they stick around anyway. Please feel free to
join #MongoDB channel and chat with people there—you may find some great hints and
tips. If you're really stuck, you'll probably be able to quickly get back on track.