Please see this comment: https://news.ycombinator.com/item?id=43863885 https://news.ycombinator.com/item?id=43863885 We have excellent metrics between PMM and

Please see this comment: https://news.ycombinator.com/item?id=43863885 https://news.ycombinator.com/item?id=43863885 We have excellent metrics between PMM and AWS Perf. Insights / Enhanced Monitoring. I assure you, on-disk temp tables were to blame. To your point, though, MySQL 5.7 does have a sub-optimal implementation in that it kicks a lot of queries out to disk from memory because of the existence of a TEXT column, which internally treated as a BLOB. Schema design is also partially to blame, since most of the tables were unnecessarily denormalized, and TEXT was often used where VARCHAR would have been more appropriate, but still.