These days there is a lot of implementations which have started in the Big Data Space/Not Only SQL Space. There is a lot of debate about which is better and how one would replace the other. One of the more interesting discussions that I have been hearing is that both SQL/Not only SQL (NoSQL) have their space. A system that combines the advantages of both the paradigms stand to gain the most I think. Not only SQL can be used a medium to get sense of the vast amounts of unstructured data, once it is in a consumable form it could be integrated with other SQL Systems. There is a interesting blog post about cons of NoSQL (Not Only SQL), of course what is also interesting is the comments made by NoSQL users below the blog post. It is a very interesting discussion.
One tends to benefit from understanding what is each systems strengths and weakness and how both can complement each other.