Summary

The coexistence of RDBMS and NoSQL data stores such as Cassandra is very much possible, feasible, and sensible; and this is the only way to get started with the NoSQL movement, unless you are embarking on a totally new product development from scratch. Here, only a few patterns have been discussed. But there are many other different ways in which Cassandra can harmoniously coexist with other genres of data stores. All the examples given in this chapter were based on hypothetical requirements just to demonstrate the design pattern. Those who actually implement the appropriate design patterns in their Cassandra data model may use it as a guidance to implement real-world solutions.

Coexistence of two or more technologies gives great confidence to the system architects as well as the end users. This opens a door to a great opportunity for the new technology to expand and flourish. Then, the next step that anybody would take is to migrate from the old technology to the new technology wherever it is applicable. There are some great use cases where the migration from RDBMS to Cassandra makes perfect sense. In the next chapter, we will discuss that further.