Is the Relational Database Not an Option in Cloud Computing?

Recent focus on Cloud Computing has increased the use of key/value databases. The most common theme for this is scalability. Though scalability is a key factor, cloud computing has other advantages that makes it attractive for vendors that do not need to deliver highly scalable applications or services.

One can imagine usage scenarios where :

• Startup companies don’t want to invest in local servers and rather pay for the computing and storage they use.
• Companies want to port existing applications or services to the cloud, without re-architecting their data layer.
• High computing power is needed for shorter periods.

Tony Bain recently published an article asking if the relational database is doomed. He focuses on the difference between the relational database and the key/value database, and the reasons for selecting one over the other. According to Tony the relational database have some challenges when it comes to scalability:

As more and more applications are launched in environments that have massive workloads, such as web services, their scalability requirements can, first of all, change very quickly and, secondly, grow very large. The first scenario can be difficult to manage if you have a relational database sitting on a single in-house server. For example, if your load triples overnight, how quickly can you upgrade your hardware? The second scenario can be too difficult to manage with a relational database in general.

He lists four reasons for selecting a key/value database over a relational database:

1. Your data is heavily document-oriented.
2. Your development environment is heavily object-oriented.
3. The data store is cheap and integrates easily with your vendor's web services platform.
4. Your foremost concern is on-demand, high-end scalability.

David Chappell wrote a paper about Azure Services Platform where he briefly talks about this topic. David points out many reasons for using a key/value database in the cloud, but also says:

…Microsoft has announced plans to evolve SQL Data Services into a more relational technology. Recall that unlike Windows Azure storage, SQL Data Services is built on SQL Server, which makes this evolution more natural. Yet whatever model it provides, the technology’s goal remains the same: providing a scalable, reliable, and low-cost cloud database for all kinds of applications.

Depending on which relational features, this might allow companies with needs as listed above to more easily adapt the technology and to a lower cost.

Databases like Drizzle, started by Brian Aker, aim for relational capabilities that can scale. Drizzle is based on the MySQL 6.0 source and optimized for cloud and net applications. For now they have removed a lot of functionality from the original source and added some new features:

• micro kernel architecture, making Drizzle more modular than MySQL
• more pluggable interfaces, such as for authenticiation and for logging
• multi-core optimization (compared to MySQL's potentially lacking multi-core optimization)
• fewer data types
• fewer engines
• less code making for a smaller and potentially more maintainable codebase

Drizzle is in Alpha, developed on Unix-like operating systems and Windows is currently not supported.