A cloud database management system (CDBMS) is a database management system that is hosted by a third-party service provider on a remote server and accessed over the Internet.
A traditional database system is installed on a server at an organization's site and data is stored and accessed directly or over a local area network (LAN). A cloud database management system, on the other hand, runs on a cloud provider's platform and data can only be stored or accessed when there is an Internet connection.
A CDMBS can be deployed in three different ways. The first way is as a virtual machine (VM) image. In this deployment model, the cloud provider sells virtual machine instances upon which a database management system can run. The provider is responsible for the infrastructure that supports the VM and the customer is responsible for uploading or purchasing the DBMS, making sure the DBMS is maintained properly and managing the databases it supports.
In the second deployment model, the cloud provider is responsible for supplying and maintaining the DBMS. The customer is responsible for managing the databases the DBMS supports and paying for storage and compute resources. This type of implementation is called Database as a service (DBaaS).
In the third deployment model, the cloud provider installs, maintains and manages the entire database implementation. This approach, which is called managed hosting, can provide a small organization with the benefits that a database provides without the administrative responsibilities and IT overhead typically required of DBMS usage.
When and how to deploy on a cloud DBMS, is not a cut and dried proposition. Before deciding whether or not to deploy in the cloud an organization should determine its requirements regarding:
Performance - A cloud DBMS typically will not provide the same level of performance as a locally-implemented DBMS simply because the data must be accessed over the Internet.
Budget - A CDBMS eliminates capital expenses for software, hardware and data center costs and translates the required investments into operational costs. For businesses that are launching new database projects or looking to move to a different DBMS, a reduction in upfront costs can be very appealing.
Data governance - If data in a CDBMS is distributed across multiple geographical locations, the regulatory compliance burden can become more difficult and impact various aspects of data governance including (but not limited to) privacy rules, disclosure requirements, retention rules and data protection requirements.
Staffing - A CDBMS can free database administrators from having to worry about tasks such as configuring and patching an on-premises DBMS and make more effective use of their time. Organizations with small or limited IT teams can benefit from hosting databases in the cloud because installation, management and other administrative issues can be offloaded to the cloud provider.