There are a number of scenarios in Drupal 8 where you might notice your MySQL database size starts growing incredibly fast, even if you're not adding any content. Most often, in my experience, the problem stems from a exponentially-increasing-in-size
cache_render table. I've had enough private conversations about this issue that I figure I'd write this blog post to cover common scenarios, as well as short and long-term fixes if you run into this issue.
Consider the following scenarios I've seen where a
cache_render table increased to 10, 50, 100 GB or more: