1. A computer-implemented method for providing workload windows in a database system having at least one cache fragment, the method comprising: collecting cache-efficiency-indicator values of an at least one cache fragment during operation of a database system over a period of time; providing approximation-function-parameter values for the collected, cache-efficiency-indicator values, an approximation function representing a relation between a cache-efficiency-indicator and size of a respective cache fragment; providing a set of workload windows based on the approximation-function-parameter values; providing workload-window information for the set of workload windows, the workload-window information including at least one approximation-function-parameter value representing each determined workload window; and storing the workload-window information for a comparison based on current, cache-efficiency-indicator values and the workload-window information.