The term “scalability” gets injected into database conversations often, but scalability discussions often end without a clear consensus. I believe this is because “scalability”, like “replication”, actually means different things to different people.
There are two dimensions to database scalability; the first dimension specifies if additional servers are involved:
- vertical: The hardware capabilities of a single database server are increased to increase throughput
- horizontal: The number of a database servers is increased to increase throughput
