Yeah, MUMPS was pretty prescient in this way. As someone who's experienced the changes first-hand, what do you feel are the most important NoSQL developments since MUMPS?
Do you have a preference on NoSQL vs relational databases?
I should also have said... they are all databases in the end. I try not to evaluate them based on the label (NoSQL, often a really bad labeling) and simply based on the problem faced and their features. Otherwise, you get lost in NoSQL vs. NewSQL vs. OldSQL vs. ___SQL.
The latest generation of NoSQL databases really tried to add to the distributed / scalability story of databases, as well as provide simpler "input", "output" and "storage mechanisms". This, often at the cost of a degree of ease of use of query languages to be able to easily analyze data.
As NoSQL movement started to come into focus, folks saw that the then dominant traditional relational / ACID model was not scaling to internet scale (too many JOINs, too hard to do ACID at that size or not needed, etc.). In reaction to "internet scale", the search turned to finding new or innovative alternatives to the relational model (which really, just represented what was the state of the art at the time). This is how we got BASE instead of ACID, and went back to key-value.. or document-oriented.. or graph-based... or Hadoop/Map-Reduce, etc. People exploring lots of alternatives.
I think people mentally "threw relational databases out" for a while as quickly as they threw out the other alternatives (the precursors to relational databases), when relational databases came along. Many have found it hard to live without relational databases.
I think modern NoSQL databases try to maximize on input/output/storage and distribution / MPP of data. By now, they give some more expressiveness for query (like MongoDB, Cassandra, Hive/Impala in the Hadoop world), although SQL still beats them in my opinion for ease of use. SQL also could have advanced as the query interface for those systems too, and if you look at the SQL:2011 standard, you'll see that it included methods for querying things that are distinctly "non-relational" (multivalue fields, etc.).
NoSQL databases also more cleanly map to object models, the dominant programming paradigm (although who knows, maybe one day that too shall change).
No, I don't have a preference of NoSQL vs relational databases in general. I believe they are complementary and maybe there isn't such a thing as a general purpose database for every use case. I do believe in the old saying, "try to use the right tool for the job". There are cases when a NoSQL database works superbly, and others where a relational database just feels right. For example, storing "objects" quickly works well with a NoSQL database vs. querying for a denormalized data warehouse seems to fit well into a relational database (ironically of course, since they are often denormalized and not third-normal-form 3NF).
Anyway, that's my take... but anyone else who has input should feel free to chime in.
Do you have a preference on NoSQL vs relational databases?