I think it's more of an issue that developers consider their options to be SQL or NoSQL when the option of using both often is a great choice. You can pick the best technology to solve individual aspects of the system.

For example, the current system I'm working on uses Oracle and Mongo, the previous used SQL Server and Redis. The main theme is to use a relational database for the structured data that we need transactional support for, e.g. orders, then use a NoSQL data for unstructured data and caching.

  > If you have a highly relational model that would benefit
  > from things like referential integrity and normalization
  > then use a relational database. If you need a massive 
  > highly scalable KVP database, use NoSQL. I don't see why 
  > people try to use a single approach as a solution 
  > to every problem.

Part of the problem is that people present this as a choice between relational and non-relational models, when the choice is actually about how the database will scale when the data set gets very large.

You're turning one false dichotomy into... I don't know the word for it, but while how it scales can be part of choosing a database system, it definitely is not the main difference between the relational and noSQL models. How your data storage will scale is an important but tangential topic that should be addressed as complementary to deciding which class of storage will help you most effectively and efficiently model your data.

  > ...[database scaling is] definitely is not the main
  > difference between the relational and noSQL models.

The post I was responding to strongly implies that one simply has to decide whether they want to use a relational model or not. I contend that framing the question this way is contributing to the misunderstandings of what the advantages and disadvantages of the popular noSQL databases are, which become very apparent when one thinks of what happens when the data set gets very large. Relational databases don't work nearly as well when you have to split the schema across multiple databases, and you can no longer use the database provided transactions or joins.

Except that virtually everyone can easily have everything in a single, fully normalized relational database on a single server. People have convinced themselves that relational databases can't scale, based on nothing at all.