Ubuntu One is a suite of cloud services including storage, sync, sharing and streaming. Couch.io (now CouchBase) held this use case up as a shining example of how CouchDB provided significant advantages in scaling a cloud synchronization service.
From the first days of Ubuntu One, before we were even in Ubuntu, we’ve had a structured data storage sync service based around CouchDB.
For the last three years we have worked with the company behind CouchDB to make it scale in the particular ways we need it to scale in our server environment. Our situation is rather unique, and we were unable to resolve some of the issues we came across. We were thus unable to make CouchDB scale up to the millions of users and databases we have in our datacentres, and furthermore we were unable to make it scale down to be a reasonable load on small client machines.
Because of this, we are turning off most of our CouchDB-related efforts. […]
This "turning off" also affects another project that Canonical was working on called desktopcouch"
For these same three years we have created and maintained desktopcouch, which is a desktop service (and related library) to access CouchDB more conveniently. Because we are no longer going to pursue CouchDB, we will no longer be developing desktopcouch;
The only response from CouchDB was on Twitter:
Reports of my death are greatly exaggerated.
As I said, it's certainly not severe enough to declare the project's 'death', but it does hurt a technology's reputation when a major company makes a drastic decision to move away from it.
However, let's not forget how Apache Cassandra has slowly turned its image around after Twitter diminished its usage in some areas. Developers just need to remember that PR is important - even for open source projects (and especially ones that have commercial services based on them).
Your best defense against the vacillations of popularity in the tech community is in the well-reasoned reviews that you find on blogs and in our very own NoSQL Zone.
In this instance, you can get a basic idea of whether or not you might need NoSQL and which store you might use from the site: http://yesnosql.appspot.com/. Check out their flowchart, which will ask you questions and give you a database based on your use case.
Of course, this resource isn't super-detailed to the point where it will give you a perfect answer. In fact, there's a recent comic that made fun of this kind of flowchart.
Hope those resource are helpful and humorous.
Update: A little more info here about how Canonical plans a slow deprication of CouchDB and how they plan to make their own layer to replace it.