Techniques to generate a pseudo-random number sequence at a desired phase using \u201cmasking\u201d to adjust the phase of the PN sequence in coarse increments to account for a large phase adjustment. In one embodiment, the second substrate has an on chip capacitor. The invention is characterised in that, for a given engine stop request phase, the engine can only be stopped or started at most a pre-determined number of times. Tracing is enabled on the database application on the server side so that a log is produced, where the log includes performance information on database operation statements that are executed.