In my experience, auto scaling has not yet been applicable in the typical sense of adding more web servers. If you use an efficient language like C# or Go, the

In my experience, auto scaling has not yet been applicable in the typical sense of adding more web servers. If you use an efficient language like C# or Go, the performance bottleneck moves to the database layer almost immediately. Caching can be added and can auto scale, but that has a tradeoff: stale data or eventual consistency. Databases are hard to scale because typically there has to be a single master instance responsible for write ordering and transaction consistency. Auto scaling the database layer is fraught with its own issues, and simply doesn’t work in practice for many common scenarios. For typical business apps, or typical web pages that might suddenly get a huge surge in usage (I.e.: Hug of death), a CDN can help… maybe. My customers keep asking for auto scale to solve their problems, when the root cause is invariably a missing index in their database.