Considering the fast evolution of NoSQL databases, the topic is now very old (from 2010). But read the comments on the original post, Hacker News, and Reddit to see what people think today about extreme denormalization, schemas, relational and NoSQL databases.

Original title and link: Reddit’s Database Has Two Tables (NoSQL database©myNoSQL)

via: http://kev.inburke.com/kevin/reddits-database-has-two-tables/

Why schema free is important for RServe? Because we plan to support many business type. Different business type usually come with different data on reservation. We want to support RServe user to able embed custom data in their reservation data

Basically, RServe is using the schema-less MongoDB as a form of multi-tenancy.

Another reason for using document databases is to (try to) avoid the complexity of such schemas:

Original title and link: MongoDB at RServe (NoSQL databases © myNoSQL)

via: http://blog.rserve.me/post/1177981948/the-reason-behind-nosql-and-schema-free-database

Document-oriented databases, with their flexible schemas, provide a nice solution. We can have older documents which vary a bit from the newer ones in the archive. The lack of homogeneity over time may mean that querying the archive is a little harder. However, keeping the data is potentially much easier.

I think this is pushing the schema migration issue from data to code, which might actually be a good idea.

Original title and link: MongoDB Use Case: Archiving (NoSQL databases © myNoSQL)

via: http://blog.mongodb.org/post/1200539426/archiving-a-good-mongodb-use-case