An SQL alert is an entry-level technique of anomaly detection. Anomaly detection is a whole world of different algorithms and it deserves a course of its own.
In this chapter, we’ve looked at a couple effective techniques to detect anomalies with a simple SQL query: comparing a number of events (errors/signups/etc) to 0 or its average value already tells us a lot about health of our systems. Remember 80/20 rule – most of the time it’s more than enough to start with SQL alerts for spotting critical problems in our processes and data.
Whether you...