The notion of a database silo - that is, a single database that contains everything and operates in isolation - is a rapidly fading concept in most companies. Many use multiple databases to take advantage of the different range of functionality, from their transactional store, to caching and session stores using NoSQL and, more recently, the transfer of information into analytical stores such as Hadoop.
This raises a problem when it comes to moving the data about. There are many different solutions available if all you want to do is move some data between systems through import and export. These are clumsy solutions, they can be scripted, but more usually you want to provide a regular stream of changes into Hadoop so that you can process and analyze the data as quickly as possible. In this article, we'll examine the traditional dump and load solutions and look at a solution that enables real-time replication of data from MySQL and Oracle into Hadoop.