Agreed. I have a handful of tables with over 2 billion rows and have experienced no issues. One database is 2.5TB in size. I feel like 20 million rows is a relatively small MySQL table.
It's related to user activity, along the lines of products a user views. The other large tables in the billions of rows are about analyzing how products are performing on other websites over time, helping to determine past and current trends for businesses.
We have two tables at nearly 2 billion rows for line items on invoices (we aggregate data for a substantial portion of a major industry). We have ~20 tables that are over 100 million rows but less than 1 billion. Looks like another ~20 tables over 20 million.
