Caching, memoization, and event-logging can be handled by wrapper objects that implement the interface so the base object doesn't need to contain all these layers of outside concerns. Let each class focus on it's single area of use.

interface Store { Query() }

// these all have the Query() method

type/class MySQL implements Store

type/class Cache implements Store

type/class Logger implements Store

var db Store

db = new Logger(new Cache(new MySQL()))