> The optimum query plan depends on a lot of dynamically changing factors Except … I’m part of a large organization with a very thorough incident post-mortem p

> The optimum query plan depends on a lot of dynamically changing factors Except … I’m part of a large organization with a very thorough incident post-mortem process and I’ve read a lot of analyses that end up blamed on the dreaded “query plan flip.” This ends up being an unplanned change that has an unexpected perf cost (and no real “rollback”) and causes an outage. The lesson I’ve seen learned over and over is to have very good understanding (and constant re-evaluation) of your hot queries’ perf , and to lock the query plan so it can only change when you intend it to.