There are a huge and ridiculous number of NoSQL databases on the market and the truth is that there is not enough market out there to sustain them all. This means that a bunch of them will eventually go belly up. This is especially true bearing in mind that many of these companies are open source and have miniscule numbers of paying customers. Of course, this is the gamble that the VCs take but I think there are likely to be a lot more losers than winners. On the other hand the winners may win big.

But there's another consequence of this plethora of suppliers that most of us have never heard of. The thought process goes something like this: "I've never heard of you … oh, you're a NoSQL vendor … in that case I'll wish you the best of British … goodbye". Only, that approach can be a mistake: because there are NoSQL companies that you may not have heard of that actually do have a sound business model and a decent customer base. Of course, they are the exception to the rule but they do exist.

I was reminded of this today when I got a press release from MarkLogic (they've introduced a free developer license for their Enterprise Edition and also announced a Mongo2MarkLogic converter). I meant to write about them last year but, what with one thing and another, didn't get around to it. So, what makes MarkLogic different from your ordinary, average run-of-the-mill NoSQL vendor?

Well, first, they were around before the whole trend for NoSQL became fashionable - the company was founded in 2001. Second, they have never been an open source vendor. Third, they have over 350 real, live, actual paying enterprise customers (many of them major companies) and, perhaps most importantly, the product is ACID compliant. That seems like a contradiction in terms doesn't it? NoSQL and ACID compliant!

As might be suggested by the Mongo converter that the company has just introduced, MarkLogic is especially focused on unstructured data. Thus, for example, the BBC built its web site for the London Olympics last year based on MarkLogic. Warner Brothers uses the product as catalogue storage for the trailers it makes for its various movies. In both case the product's integrated search engine is the icing on top of the database. Actually, it's a federated search engine and it has more conventional uses as well: for instance, one global investment bank is using it to establish its risk position across geographies.

The underlying architecture of MarkLogic is XML-based but the company has the product running on top of HDFS in its labs though this is not generally available as yet. It is possible to archive data to HDFS environments and MarkLogic has policy definition capabilities provided for ILM (information lifecycle management) purposes. You can still search across the archived HDFS environment using the MarkLogic search engine. As one might expect from an XML-based technology, access may be made via XQuery but there is also support for JSON and SQL access as well as a REST API.

So: not all NoSQL products and vendors are by any means equal. Indeed, MarkLogic tends to compete with relational databases and technology rather than other NoSQL suppliers. And that, perhaps, proves the point that it is dangerous to tar all NoSQL vendors with the same brush. Because MarkLogic is clearly an exception.