Oracle Exam 1Z0-1085-20 Topic 5 Question 33 Discussion

Horizontal scaling means that you scale by adding more machinesinto your pool of resources whereasVertical scaling means that you scale by adding more power (CPU, RAM) to an existing machine.

An easy way to remember this is to think of a machine on a server rack, we add more machines across thehorizontaldirection and add more resources to a machine in theverticaldirection.

With horizontal-scaling it is often easier to scale dynamically by adding more machines into the existing pool --- Vertical-scaling is often limited to the capacity of a single machine, scaling beyond that capacity often involves downtime and comes with an upper limit.

https://medium.com/@abhinavkorpal/scaling-horizontally-and-vertically-for-databases-a2aef778610c