From 0 to Millions: A Guide to Scaling Your App - Part 2

Llama 5.0 - Add Cache After implementing the primary-replica architecture, most applications should be able to scale to several hundred thousand users, and some simple applications might be able to reach a million users. However, for some read-heavy applications, primary-replica architecture might not be able to handle traffic spikes well. For our e-commerce example, flash sale events like Black Friday sales in the United States could easily overload the databases. If the load is sufficiently heavy, some users might not even be able to load the sales page.