This blog is about technology, programming, video games, books and other related topics. It is published by Mark Papadakis.

Monolithic RDBMs are losing ground to key-value data stores, particularly persistent distributed in nature. mySQL mounting problems was perhaps the key reason (pun intended) people looked elsewhere. Google's brilliant engineers realized that a key/value data model can satisfy the needs of almost every class of application that needs a datastore backend.

Key/value datastores are simple to build, easy to understand, easy to optimize, easy to scale. The, now famous, CAP theorem states that it is not practically possible to guarantee consistency, availability and partitioning resilience/tolerance all at the same time; one of those traits has to be sacrificed. Again, most applications really do not require all three to function. The CAP theorem is most likely derived from the Project Triangle mode.

Most web-based applications are built on simple data models. Most web-applications eventually suffer from service capacity and availability issues(i.e scalability woes). It is trivial to scale out(vertically) application logic processing(application servers), HTTP requests processing(web servers, load balancers).
It is not easy to scale out an RDBMS. Some expensive systems(Oracle, etc) provide ways to address those issues (e.g Oracle RAC) but its expensive to deploy them, and most of them rely on a shared everything setup which just doesn't work in the long run. (Shared nothing is really the way to go).

Google released a bunch of papers ( actually, a bazillion of papers ), many of them defining and shaping the development of future related technologies. Namely, the papers describing GFS, BigTable, MapReduce (and of course, the paper the changed everything, "The Anatomy of a Large-Scale Hypertextual Web Search Engine" ) steered everyone to the right direction.

In the datastores domain, Hadoop/HBase, Radix, Cassandra and others, based on BigTable and Amazon's Dynamo papers, all relying on the simple key/value datastore model, are gaining market share - rightly so. Coupled with Memmache and similar services(in-memory key/value stores) they are solving the problems of service capacity and availability. This is a paradigm shift. Its a downhill for heavy-footprint, complex and inflexible datastore systems. They wont go away but will not be such a valuable(pun intended) component in tomorrow's technology landscape.

We are going to gradually migrate from RDBMs - though, we are not relying that much on them nowadays - to a key/value datastore (we are currently building one, also based on BigTable and Dynamo ). If nothing else, those simple systems are both simple and beautiful (for the most part).

Tagged with: scalability , storage , technology , google , databases , programming
Published at Saturday, 13 March 2010 8:14 pm