MongoDB is a non-relational database that stores data in JSON-like documents, offering features such as easy replication, scalability, and a simple configuration. Unlike traditional RDBMS, it sacrifices some aspects like transactions and joins for horizontal scalability and eventual consistency. It can run on commodity hardware and various operating systems, with resources available for further exploration and learning.

1. Chris Westin
@cwestin63
© Copyright 2010 10gen Inc.

2. What is MongoDB?
• One of the new breed of non-relational
(“NoSQL”) databases
• A document store
• Instead of flat records (sets of scalars), stores
JSON documents
• Scalars
• Array-valued fields
• Document-valued fields
• Open source

3. Why MongoDB?
• Availability
• Easy replication
• In principle, similar to MySQL master-slave
• Automated failover
• Failure of the “primary” (current master) is detected,
and a “secondary” (slave) is selected and takes
over automatically

4. Why MongoDB?
• Scalability
• Easy replication
• Scale reads by permitting reads from secondaries
• Built-in sharding
• Scale writes by spreading load across multiple
shards – each is a replica set
• Shards can be added or removed at will
• No penalty for guessing wrong at start
• System automatically re-balances shards if they
grow disproportionately

5. Why MongoDB?
• Simplicity
• Simple configuration
• Very few startup parameters
• Flexible document model
• Structured data
• Doesn’t force unnecessary normalization
• Natural-looking language bindings
• Client drivers use native language constructions to
represent documents

6. MongoDB is not an RDBMS
• Sacrifices made for horizontal scalability
• Eventual Consistency
• Secondaries are not replicas maintained by
distributed transactions
• No transactions
• No joins
• No SQL
• Simpler QBE-style query language

7. Where does MongoDB Run?
• Designed for commodity hardware
• Can run on O&O infrastructure or in cloud
environments
• Runs on Windows and most flavors of linux
• OSX works, but is not recommended for
production

8. Where can I find out more?
• Tutorials
• http://try.mongodb.org
• http://openmymind.net/2011/3/28/The-Little-MongoDB-
Book/
• Documentation wiki
• http://www.mongodb.org/
• mongodb-user on Google groups
• http://groups.google.com/group/mongodb-user
• 10gen
• http://www.10gen.com/
• Presentations, webinars
• http://www.10gen.com/what-is-mongodb
• Support, training, consulting