Before we get into databases, we have to address one of the attributes of a high-quality software system: managing logged information, including normal system activity, system errors, and debugging information. Logs give us an insight into the behavior of the system. How much traffic is it getting? If it's a website, which pages are people hitting the most? How many errors occur and of what kind? Do attacks occur? Are malformed requests being sent?
Log management is also an issue. Log rotation means regularly moving the log file out of the way, to start with a fresh log file. You should process logged data to produce reports. A high priority on screening for security vulnerabilities is a must.
The Twelve Factor application model suggests simply sending logging information to the console, and then some other software system captures that output and directs it to a logging service. Following their advice can reduce system complexity by having fewer things that can break. In a later chapter...