Why NoSQL

Ramji Narasimhan:

The fundamental reasons behind [the move away from traditional SQL based solutions] are simple:

• Not all your applications need relationships between data to be explicitly stored along with the data
• Moving the responsibility of interpreting data relationships out of the store allows for storing the data anywhere. That means you can simply add boxes as your data grows
• Storing your data as a set of key-value pairs as opposed to hard wired tables allows for more flexibility in storage design
• Absence of a pre-defined schema/tables allows you to easily extend your data model
• Data operations, both read and write, tend to be simple and lightweight in the absence of SQL processing and explicit relationship constraints

Just one comment: relationships are almost always needed, but the way they are represented is changed:

• data is denormalized, so entities involved in relationships live in the same space
• relationships are created/restored at the application level

Original title and link: Why NoSQL (NoSQL databases © myNoSQL)

via: http://www.virtusa.com/blog/index.php/2011/04/facebook-like-scalability-with-nosql/